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Manual of Ice (MANICE)

 

MANICE is the Manual of Standard Procedures for Observing and Reporting Ice Conditions.

MANICE is the authoritative document for observing all forms of ice:

  • Sea Ice,
  • Lake and River Ice, and
  • Ice of Land Origin

The most recent version of MANICE was revised in June 2005.

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Table of Contents

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Foreword

MANICE is the authoritative document for observing all forms of Sea, Lake and River Ice, as well as Ice of Land Origin. It describes the standard procedures of the Canadian Ice Service for observing, recording and reporting ice conditions.

MANICE has been prepared in accordance with internationally recommended terminology and symbology established by the World Meteorological Organization (WMO). It describes procedures that are completely compatible with World Meteorological Organization nomenclature (cf. 1), coding and observing practices, along with additional procedures, coding and symbology adapted for Canadian use or, in the case of icebergs, used in conjunction with the International Ice Patrol (IIP).

This manual has been reviewed, revised and updated by the Operations and Field Services divisions of the Canadian Ice Service. This document has been updated to reflect changes in technology, practices, colour codes and iceberg message coding. Although amendments are required and important there were not enough significant changes to publish a completely new version of the standards manual. Therefore this edition will be considered a revision of version 9 published in April 2002.

Amendments and Corrections
Amendments and corrections will be issued when warranted. All holders of the manual are responsible for keeping their copies current. When amendments have been received, they should be recorded on page xi ("Record of Amendments").

Inquiries
Please direct any inquiries on the content of this manual to the Canadian Ice Service, through appropriate channels. Local changes or deviations from these instructions are not permitted unless authorized by the Assistant Deputy Minister, Meteorological Service of Canada.

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Introduction

The information from ice observations is very important and serves many purposes and needs. Ice observations and carefully prepared records have long-range, as well as immediate value.

  • Some people require up-to-the-minute information; for example, an icebreaker captain needs current ice reports and forecasts.
  • Others require data having daily, monthly or long-term climatological significance; for instance, marine engineers require climatological and/or monthly data. The decision to construct a dock in a certain locality or the strengthening a vessel structure should have in order to withstand ice stress will depend on ice data obtained over a long period.

Ice observations may be made from:

  • fixed-wing aircraft,
  • the deck of a ship,
  • a helicopter, or
  • a shore base.

In each case, the perspective of the observer differs and adjustments need to be made to the observing procedures.

Since ice is a global phenomena, ice information must be freely exchanged between countries throughout the world. This requires coordination and standardization of practices and procedures and the efficient exchange of ice data. The World Meteorological Organization has undertaken these tasks, including promotion of further application of ice information services to shipping, marine resource activities and other human safety activities. The results have been international codes and standardized nomenclature and symbology.

To carry out resolutions and to discuss and coordinate ice activities within certain geographical areas, World Meteorological Organization Members are grouped in six Regional Associations, among which Region IV comprises Canada, the United States, Mexico and the Central American countries.

To meet special requirements, a Member or group of Members within a region may develop a special reporting procedure. For instance, the Great Lakes Ice Nomenclature was developed through bilateral agreement between Canada and the United States to meet the local requirements of shipping and other uses. Such codes or code changes are called "national practices".

Although international and national codes may both be used in ice reporting, ice messages for interregional broadcast must use the International Code.

This manual has been prepared with due consideration to the recommended practices and procedures set down by the World Meteorological Organization (cf. 1) and the Meteorological Service of Canada. All statements throughout this manual shall be regarded as authoritative and shall be considered by the observer to be instructions.

The word "shall" is used in this manual to indicate that instructions are mandatory and must be followed. The word "should" is used to denote a recommended practice.

An "Ice Services Specialist" (ISS) is a member of the Meteorological Service of Canada who is trained and qualified to make ice observations and reports, or a person authorized or qualified to do so by the Assistant Deputy Minister.

It is the duty of the observer to report ice conditions as they actually exist at the time of observation. He/she is responsible for keeping a close and continuous watch on the ice while on duty, and his/her records and reports shall be as complete and accurate as possible. Prompt and accurate reports are necessary for the provision of forecasts and ice-warning services, and may be the means of preventing property damage and loss of life. Delayed reports are of less value for forecasting and for operational decision-making. However, if communication or other difficulties delay or prevent distribution of reports, the observer shall continue to observe the ice and record the observations for later transmission. Before finally being transferred to the Canadian Ice Service archives, observed ice data is subjected to an analysis or review, which may reveal errors.

The observer must be competent and trained to make observations accurately and to code and chart the resulting reports for transmission as quickly as possible. He/she should realize, however, that it is neither possible nor desirable to prepare detailed instructions to cover reporting and coding of ice in all of its forms. Therefore, initiative and resourcefulness in dealing with unusual conditions are most important in observing ice.

Data held at the Canadian Ice Service in Ottawa is used in the preparation of official publications, and by both government and industry in the preparation of statistical analyses for decision-making purposes. The accuracy of the archived data determines, to a large degree, the quality of the publication or analysis; it is therefore extremely important to take suitable measures to ensure that observed data is of the highest quality consistent with reasonable cost.

This manual deals principally with procedures for the visual observation of ice from various platforms. Where appropriate, electronic aids such as airborne or satellite radar for ice data collection are referred to; however, for a much more detailed description of Side Looking Airborne Radar and Synthetic Aperture Radar technical operation and image interpretation, please refer to the following documents:

  • Side-Looking Airborne Radar Users Manual (cf. 5), and
  • Synthetic Aperture Radar Ice Interpretation Guide (cf. 4).

These guides are also available from the Canadian Ice Service.

The terminology has been prepared with the needs of the international marine community in mind; it is therefore highly oriented toward terms relating to sea ice and ice of land origin found at sea. Nevertheless, many of the terms apply equally to lake ice and/or river ice, particularly those relating to floe sizes and ice-dynamic processes. A section on lake ice nomenclature has been added, and this manual is now the authoritative guide for observing all types of floating ice, including ice of land origin.

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Chapter 1: General Terminology

1.1 Floating Ice

Any form of ice found floating in water. The principal kinds of floating ice are lake ice, river ice and sea ice which form by the freezing of water at the surface and glacier ice formed on land or in an ice shelf. This term includes ice that is stranded or grounded.

Sea Ice: Any form of ice found at sea which has originated from the freezing of water

Lake Ice: Ice formed on a lake, regardless of observed locations.

River Ice: Ice formed on a river, regardless of observed location.

Ice of Land Origin: Ice formed on land or in an ice shelf, found floating in water.

1.2.1 New Ice

A general term for recently formed ice which includes frazil ice, grease ice, slush and shuga. These types of ice are composed of ice crystals which are only weakly frozen together (if at all) and have a definite form only while they are afloat.

Frazil Ice: Fine spicules or plates of ice suspended in water.

Grease Ice: A later stage of freezing than frazil ice where the crystals have coagulated to form a soupy layer on the surface. Grease ice reflects little light, giving the water a matte appearance.

Slush: Snow which is saturated and mixed with water on land or ice surfaces or as a viscous floating mass in water after a heavy snowfall.

Shuga: An accumulation of spongy white ice lumps having a diameter of a few centimetres across; they are formed from grease ice or slush and sometimes from anchor ice rising to the surface.

1.2.2 Nilas

A thin elastic crust of ice, easily bending on waves and swell and under pressure growing in a pattern of interlocking "fingers" (finger rafting). Nilas has a matte surface and is up to 10 centimetres in thickness and may be subdivided into dark nilas and light nilas.

Dark Nilas: Nilas up to 5 centimetres in thickness and which is very dark in colour.

Light Nilas: Nilas which is more than 5 centimetres in thickness and lighter in colour than dark nilas.

Ice Rind: A brittle, shiny crust of ice formed on a quiet surface by direct freezing or from grease ice, usually in water of low salinity. It has a thickness of about 5 centimetres. Easily broken by wind or swell, commonly breaking into rectangular pieces.

1.2.3 Young Ice

Ice in the transition stage between nilas and first-year ice, 10-30 centimetres in thickness. May be subdivided into grey ice and grey-white ice.

Grey Ice: Young ice 10-15 centimetres thick, less elastic than nilas and breaks on swell. It usually rafts under pressure.

Grey-White Ice: Young ice 15-30 centimetres thick. Under pressure it is more likely to ridge than to raft.

1.2.4 First-year Ice

Sea ice of not more than one winter's growth, developing from young ice; 30 centimetres or greater. It may be subdivided into thin first-year ice - sometimes referred to as white ice -, medium first-year ice and thick first-year ice.

Thin First-year Ice/White Ice -First Stage: 30-50 centimetres thick.

Thin First-year Ice/White Ice-Second Stage: 50-70 centimetres thick.

Medium First-year Ice: 70-120 centimetres thick.

Thick First-year Ice: Greater than 120 centimetres thick.

1.2.5 Old Ice

Sea ice which has survived at least one summer's melt. Topographic features generally are smoother than first-year ice. It may be subdivided into second-year ice and multi-year ice.

Second-year Ice: Old ice which has survived only one summer's melt. Thicker than first-year ice, it stands higher out of the water. In contrast to multi-year ice, summer melting produces a regular pattern of numerous small puddles. Bare patches and puddles are usually greenish-blue.

Multi-year Ice: Old ice which has survived at least two summer's melt. Hummocks are smoother than on second-year ice and the ice is almost salt-free. Where bare, this ice is usually blue in colour. The melt pattern consists of large interconnecting, irregular puddles and a well-developed drainage system.

1.3 Stages of Development of Lake Ice

New Lake Ice: Recently formed ice less than 5 centimetres thick.

Thin Lake Ice: 5-15 centimetres thick.

Medium Lake Ice: 15-30 centimetres thick.

Thick Lake Ice: 30-70 centimetres thick.

Very Thick Lake Ice: Greater than 70 centimetres thick.

1.4 River Ice

Because of the effect of salinity on the ice formation process, ice shall be coded as follows: ice which forms in water with a salinity of more than 24.7 parts per thousand will be coded as sea ice; otherwise the lake ice code is used. In the St. Lawrence River it is Canadian practice to use sea ice terminology down river from St. Lambert lock and lake ice terminology up river from St. Lambert lock, unless otherwise noted.

1.5 Ice of Land Origin

1.5.1 Terminology

Firn: Old snow which has recrystallized into a dense material. Unlike ordinary snow, particles are to some extent joined together; but, unlike ice, the air spaces in it still connect with each other.

Glacier Ice: Ice in or originating from a glacier, whether on land or floating on the sea as icebergs, bergy bits, growlers or ice islands.

Glacier: A mass of snow and ice continuously moving from higher to lower ground or, if afloat, continuously spreading. The principal forms of glaciers are: inland ice sheets, ice shelves, ice streams, ice caps, ice piedmonts, cirque glaciers and various types of mountain (valley) glaciers.

Ice Wall: An ice cliff forming the seaward margin of a glacier which is aground. The rock basement being at or below sea level (see "ice front", below). The term also includes the seaward face of non-active glaciers.

Ice Stream: Part of an inland ice sheet in which the ice flows more rapidly and not necessarily in the same direction as the surrounding ice. Margins are sometimes clearly marked by a change in direction of the surface slope but may be indistinct.

Glacier Tongue: Projecting seaward extension of a glacier, usually afloat. In the Antarctic, glacier tongues may extend over many tens of kilometres.

Iceberg Tongue: A major accumulation of icebergs projecting from the coast, held in place by grounding and joined together by fast ice.

Ice Shelf: A floating ice sheet of considerable thickness showing 2 metres or more above sea level, attached to the coast. They usually have great horizontal extent and a level or gently undulating surface. Ice shelf growth occurs by annual snow accumulation and also by the seaward extension of land glaciers. Limited areas may be aground. The seaward edge is termed an ice front.

Ice Front: The vertical cliff forming the seaward face of an ice shelf or other floating glacier, varying in height from 2 to 50 metres or more above sea level.

Calving: The breaking away of a mass of ice from an ice wall, ice front or iceberg.

Iceberg: A massive piece of ice of greatly varying shape, protruding 5 metres or more above sea level, which has broken away from a glacier and which may be afloat or aground. They may be described as tabular,domed, pinnacled, wedged, drydocked or blocky. Sizes of icebergs are classed as small, medium, large and very large.

1.5.2 Shapes of Calved Ice of Land Origin

Tabular Iceberg: A flat-topped iceberg. Most show horizontal banding.

Domed Iceberg: An iceberg which is smooth and rounded on top.

Pinnacled Iceberg: An iceberg with a central spire or pyramid, with one or more spires.

Wedged Iceberg: An iceberg which is rather flat on top and with steep vertical sides on one end, sloping to lesser sides on the other end.

Drydocked Iceberg: An iceberg which is eroded such that a U-shaped slot is formed near or at water level, with twin columns or pinnacles.

Blocky Iceberg: A flat-topped iceberg with steep vertical sides.

1.5.3 Sizes of Calved Ice of Land Origin

Growler: Piece of ice smaller than a bergy bit and floating less then 1 metre above the sea surface, a growler generally appears white but sometimes transparent or blue-green in colour. Extending less than 1 metre above the sea surface and normally occupying an area of about 20 square metres, growlers are difficult to distinguish when surrounded by sea ice or in high sea state.

Bergy Bit: A piece of glacier ice, generally showing 1 to less than 5 metres above sea level, with a length of 5 to less than 15 metres. They normally have an area of 100-300 squared metres.

Small Iceberg: A piece of glacier ice extending 5 to 15 metres above sea level and with a length of 15 to 60 metres.

Medium Iceberg: A piece of glacier ice extending 16 to 45 metres above sea level and with a length of 61 to 120 metres.

Large Iceberg: A piece of glacier ice extending 46 to 75 metres above sea level and with a length of 121 to 200 metres.

Very Large Iceberg: A piece of glacier ice extending more than 75 metres above sea level and with a length of more than 200 metres.

Ice Island: A large piece of floating ice protruding about 5 metres above sea level, which has broken away from an Arctic ice shelf. They have a thickness of 30-50 metres and an area of from a few thousand square metres to 500 squared kilometres or more. They are usually characterized by a regularly undulating surface giving a ribbed appearance from the air.

Ice Island Fragment: Piece of an ice island that has broken away from the main mass.

1.6 Forms of Ice

1.6.1 Pancake Ice

Predominantly circular pieces of ice 30 centimetres to 3 metres in diameter, up to 10 centimetres in thickness, with raised rims due to the pieces striking against one another. It may form on a slight swell from grease ice, shuga or slush or as a result of the breaking of ice rind, nilas or, under severe conditions of swell or waves, of grey ice. It also sometimes forms at some depth at an interface between water bodies of different physical characteristics where it floats to the surface. It may rapidly form over wide areas of water.

1.6.2 Ice Cake

Any relatively flat piece of ice less than 20 metres across.

Small Ice Cake: An ice cake less than 2 metres across.

1.6.3 Floe

Any relatively flat piece of ice 20 metres or more across. Floes are subdivided according to horizontal extent as follows:

Small: 20-100 metres across.

Medium: 100-500 metres across.

Big: 500-2,000 metres across.

Vast: 2-10 kilometres across.

Giant: Greater than 10 kilometres across.

1.6.4 Floeberg

A massive piece of ice composed of a hummock or a group of hummocks, frozen together and separated from any surrounding ice. They may typically protrude up to 5 metres above water level.

1.6.5 Ice Breccia

Ice pieces of different stages of development frozen together.

1.6.6 Batture Floes

Large, thick, uneven and discoloured ice floes that form on the upstream side of shoals and islets in rivers when cold weather precedes or accompanies neap tides. Composed of ice of different thicknesses formed under pressure during ebb tide, the whole mass freezing together and gradually increasing in size with each successive tide. As the range increases between the neap and spring tides, large sections of grounded ice break away and drift down river. This is a Canadian description and not part of the World Meteorological Organization nomenclature.

1.6.7 Brash Ice

Accumulation of floating ice made up of fragments not more than 2 metres across, the wreckage of other forms of ice.

Jammed Brash Barrier: A strip or narrow belt of new, young or brash ice usually 100-5000 metres across formed at the edge of either floating or fast ice or at the shore. Heavily compacted, mostly due to wind action, may extend 2 to 20 metres below the surface, but does not normally have appreciable topography. Jammed brash barriers may disperse with changing winds, but can also consolidate to form a strip of unusually thick ice in comparison to the surrounding ice.

Agglomerated Brash: This term is similar to Jammed Brash Barrier but is not consolidated. This is a Canadian description and not part of the World Meteorological Organization nomenclature.

1.2 Stages of Development of Sea Ice

Photo of ice fast.
Photo of fast ice.
Photo: Serge Leger © Environment Canada, 2014

1.6.8. Fast Ice

Ice which forms and remains fast along the coast. It may be attached to the shore, to an ice wall, to an ice front, between shoals or grounded icebergs. Vertical fluctuations may be observed during changes of sea level. It may be formed "in-situ" from water or by freezing of floating ice of any age to shore and can extend a few metres or several hundred kilometres from the coast. It may be more than one year old in which case it may be prefixed with the appropriate age category (old, second-year or multi-year). If higher than 2 metres above sea level, it is called an ice shelf.

Young Coastal Ice: The initial stage of fast ice formation consisting of nilas or young ice; its width varying from a few metres up to 100-200 metres from the shoreline.

1.6.9 Icefoot

A narrow fringe of ice attached to the coast, unmoved by tides and remaining after the fast ice has moved away.

1.6.10 Anchor Ice

Submerged ice attached or anchored to the bottom, irrespective of the nature of its formation.

1.6.11 Grounded Ice

Floating ice which is aground in shoal water.

Stranded Ice: Ice which had been floating and has been deposited on the shore by retreating high water.

Grounded Hummock: A hummocked, grounded ice formation. There are single grounded hummocks and lines (or chains) of grounded hummocks.

1.7 Arrangement of the Ice

1.7.1 Drift Ice/Pack Ice

Term used in a wide sense to include any area of ice, other than fast ice, no matter what form it takes or how it is disposed. When concentrations are high, i.e., 7/10 or more, the term pack ice is normally used. When concentrations are 6/10 or less the term drift ice is normally used.

1.7.2 Ice Cover

The ratio of an area of ice to the total area of water surface within some large geographic locality. This locality may be global, hemispheric or prescribed by a specific oceanographic entity such as Baffin Bay or the Barents Sea.

1.7.3 Concentration

The ratio expressed in tenths describing the area of the water surface covered by ice as a fraction of the whole area. Total concentration includes all stages of development that are present; partial concentration refers to the amount of a particular stage or of a particular form of ice and represents only a part of the total.

Consolidated Ice: Floating ice in which the concentration is 10/10 and the floes are frozen together.

Compact Ice: Floating ice in which the concentration is 10/10 and no water is visible.

Very Close Pack/Drift: Floating ice in which the concentration is 9/10 to less than 10/10.

Close Pack/Drift: Floating ice in which the concentration is 7/10 to 8/10, composed of floes mostly in contact with one another.

Open Drift: Floating ice in which the concentration is 4/10 to 6/10, with many leads and polynyas. Floes generally not in contact with one another.

Very Open Drift: Ice in which the concentration is 1/10 to 3/10 and water dominates over ice.

Open Water: A large area of freely navigable water in which ice is present in concentrations less than 1/10. No ice of land origin is present.

Bergy Water: An area of freely navigable water in which ice of land origin is present. Other ice types may be present, although the total concentration of all other ice is less than 1/10.

Ice Free: No ice present. If ice of any kind is present, this term shall not be used.

1.7.4 Ice Distribution

Ice Field: Area of floating ice, consisting of any size of floes and greater than 10 kilometres across.

Large Ice Field: An ice field over 20 kilometres across.

Medium Ice Field: An ice field 15-20 kilometres across.

Small Ice Field: An ice field 10-15 kilometres across.

Ice Patch: An area of ice less than 10 kilometres across.

Ice Massif: A variable accumulation of pack or very close pack, covering hundreds of square kilometres and found in the same region every summer.

Belt: A large feature of pack/drift ice arrangement longer than it is wide; from 1 kilometre to more than 100 kilometres in width.

Tongue: A projection of the ice edge up to several kilometres in length, caused by wind or current.

Strip: Long narrow area of pack/drift ice, about 1 kilometre or less in width, usually composed of small fragments detached from the main mass of ice, which run together under the influence of wind, swell or current.

Bight: Extensive crescent-shaped indentation in the ice edge formed by either wind or current.

Ice Jam: An accumulation of broken ice caught in a narrow channel.

1.7.5 Openings in the Ice

Fracture: Any reak or rupture through very close pack ice, compact ice, consolidated ice, fast ice or a single floe resulting from deformation processes. Fractures may contain brash ice and/or be covered with nilas and/or young ice. Their lengths may vary from a few metres to many kilometres.

Fracture Zone: An area which has a great number of fractures. Fractures are subdivided as follows:

Very Small Fracture: 1 to 50 metres wide.

Small Fracture: 50 to 200 metres wide.

Medium Fracture: 200 to 500 metres wide.

Large Fracture: Greater than 500 metres wide.

Crack: Any fracture of fast ice, consolidated ice or a single floe which may have been followed by separation ranging from a few centimetres to 1 metre.

Tide Crack: Crack at the line of junction between an immovable ice foot or ice wall and fast ice,the latter subject to rise and fall of the tide.

Flaw: A narrow separation zone between floating ice and fast ice, where the pieces of ice are in a chaotic state. Flaws form when ice shears under the effect of a strong wind or current along the fast ice boundary.

Lead: Any fracture or passageway through ice which is navigable by surface vessels.

Shore Lead: A lead between ice and the shore or between ice and an ice front.

Flaw Lead: A passageway between ice and fast ice which is navigable by surface vessels.

Polynya: Any non-linear shaped opening enclosed by ice. May contain brash ice and/or be covered with new ice, nilas or young ice; sub-mariners refer to these as skylights.

Shore Polynya: A polynya between ice and the coast or between ice and an ice front.

Flaw Polynya: A polynya between ice and fast ice.

Recurring Polynya: A polynya which recurs in the same position every year.

1.7.6 Ice Edge

The demarcation at any given time between open water and sea, lake or river ice whether fast or drifting.

Compacted Ice Edge: Clear-cut ice edge compacted by wind or current, usually on the windward side of an area of ice.

Diffuse Ice Edge: Poorly defined ice edge limiting an area of dispersed ice, usually on the leeward side of an area of ice.

Ice Limit: Climatological term referring to the extreme minimum or extreme maximum extent of the ice edge in any given month or period based on observations over a number of years. This term should be preceded by minimum or maximum.

Mean Ice Edge: Average position of the ice edge in any given month or period based on observations over a number of years. Other terms which may be used are mean maximum ice edge and mean minimum ice edge.

Median Ice Edge: The position of the ice edge where its frequency of occurrence is fifty percent.

Fast Ice Edge: The demarcation at any given time between fast ice and open water.

1.7.7 Ice Boundary

The demarcation at any given time between fast ice and floating ice or between areas of ice of different concentrations, types and/or floe sizes.

Fast Ice Boundary: The ice boundary at any given time between fast ice and the pack/drift ice.

Concentration Boundary: A line approximating the transition between two areas of floating ice with different concentrations.

1.7.8 Iceberg Limit

The limit at any given time between ice of land origin and the open sea or sea ice.

Limit of all known Ice: The limit at any given time between icebergs and/or sea-ice infested watersand ice-free waters.

Mean Iceberg Limit: Average position of the limit of icebergs at any given time based on observations over a number of years.

Median Iceberg Limit: The position where the historical or statistical frequency of occurrence of the iceberg limit is fifty percent.

Minimum Iceberg Limit: Minimum limit of icebergs based on observations over a period of years.

Maximum Iceberg Limit: Maximum limit of icebergs based on observations over a period of years.

1.8 Ice Surface Features

1.8.1 Level Ice

Ice unaffected by deformation.

1.8.2 Deformed Ice

A general term for ice which has been squeezed together and in places forced upwards and downwards. Subdivisions are rafted ice, ridged ice and hummocked ice.

Rafted Ice: Type of deformed ice formed by one piece of ice overriding another.

Finger Rafted Ice: Type of rafted ice in which floes thrust "fingers" alternately over and under the other,common in nilas.

Ridge: A line or wall of broken ice forced up by pressure. It may be fresh or weathered. The submerged volume of broken ice under a ridge, forced downwards by pressure, is termed an ice keel.

New Ridge: Ridge with sharp peaks and slope of sides usually 40 degrees or more. Fragments are visible from the air at low altitude.

Weathered Ridge: Ridge with peaks slightly rounded and slope of sides usually 30 to 40 degrees. Individual fragments are not discernible.

Very Weathered Ridge: Ridge with tops very rounded. Slope of sides usually 20 to 30 degrees.

Aged Ridge: Ridge which has undergone considerable weathering. These ridges are best described as undulations.

Consolidated Ridge: A ridge in which the base has frozen together.

Ridged Ice: Ice piled haphazardly one piece over another in the form of ridges or walls. Usually found in first-year ice.

Ridged Ice Zone: An area of many ridges with similar characteristics (rubble field).

Hummock: A hillock of broken ice which has been forced upwards by pressure. May be fresh or weathered. The submerged volume of broken ice under the hummock, forced downwards by pressure, is termed a bummock.

Hummocked Ice: Ice piled haphazardly one piece over another to form an uneven surface. When weathered ithas the appearance of smooth hillocks.

1.8.3 Other Surface Feature Definitions

Standing Floe: A separate floe standing vertically or inclined and enclosed by rather smooth ice.

Ram: An underwater ice projection from an ice wall, ice front, iceberg or floe. Its formation is usually due to a more intensive melting and erosion of the unsubmerged part.

Bare Ice: Ice without snow cover.

Snow-Covered Ice: Ice covered with snow.

Sastrugi: Sharp, irregular ridges formed on a snow surface by wind erosion and deposition. On mobile floating ice the ridges are parallel to the direction of the prevailing wind at the time they were formed.

Snowdrift: An accumulation of wind-blown snow deposited in the lee of obstructions or heaped by wind eddies. A crescent-shaped snowdrift, with ends pointing down-wind, is called a snow barchan.

1.8.4 Ice Deformation Processes

Fracturing: Pressure process whereby ice is permanently deformed and rupture occurs. This term is most commonly used to describe breaking across very close ice, compact ice and consolidated ice.

Hummocking: Pressure process by which ice is forced into hummocks. When the floes rotate in the process it is termed screwing.

Ridging: The pressure process by which ice is forced into ridges.

Rafting: Pressure process whereby one piece of ice overrides another. Most common in new and young ice.

Finger Rafting: Type of rafting whereby interlocking thrusts are formed, each floe thrusting "fingers" alternately over and under the other. This is commonly found in nilas.

Weathering: Processes of ablation and accumulation which gradually eliminate irregularities in an ice surface.

1.8.5 Ice Motion Processes

Diverging: Ice fields or floes in an area that are subjected to a diverging motion, reducing ice concentration and/or relieving stresses in the ice.

Compacting: Pieces of floating ice are said to be compacting when subjected to a converging motion, which increases ice concentration and/or produces stresses which may result in ice deformation.

Shearing: An area of floating ice is subject to shear when the ice motion varies significantly in the direction normal to the motion, subjecting the ice to rotational forces. These forces may result in phenomena similar to a flaw.

1.9 Stages of Melting

Photo of melting ice
Photo of melting ice.
Photo : Benoit Simard © Environment Canada, 2012

Puddle: An accumulation of water on ice, mainly due to melting snow, but in the more advanced stages also to the melting of ice.

Thaw Holes: Vertical holes in ice formed when surface puddles melt through to the underlying water.

Dried Ice: Ice surface from which water has disappeared after the formation of cracks and thaw holes. During the period of drying the surface whitens.

Rotten Ice: Ice which has become honeycombed and is in an advanced state of disintegration.

Flooded Ice: Ice which has been flooded and is heavily loaded by water or water and wet snow.

Frozen Puddle: A puddle which has frozen over.

1.10.1 Sky and Air Indications

Water Sky: Dark streaks on the underside of low clouds, indicating the presence of water features in the vicinity of ice.

Ice Blink: A whitish glare on low clouds above an accumulation of distant ice.

Frost Smoke: Fog-like clouds formed by the contact of cold air with relatively warm water. These can appear over openings in the ice or leeward of the ice edge and may persist while ice is forming.

1.10.2 Terms related to Surface shipping

Beset: Situation in which a vessel is surrounded by ice and unable to move.

Ice-Bound: A harbour, inlet, etc., is said to be ice-bound when navigation by ships is prevented, on account of ice, except possibly with the assistance of an icebreaker.

Nip: Ice is said to nip when it forcibly presses against a ship. A vessel so caught, though undamaged, is said to have been nipped.

Ice Under Pressure: Ice in which deformation processes are actively occurring. It is a potential impediment or danger to shipping.

Difficult Area: A general qualitative expression to indicate that the relative severity of the ice conditions, prevailing in an area, are such that navigation in it is difficult.

Easy Area: A general qualitative expression to indicate that ice conditions, prevailing in an area, are such that navigation is not difficult.

Iceport: An embayment in ice, often of a temporary nature, where ships can moor alongside and unload directly onto the ice itself.

1.10.3 Terms related to Submarine Navigation

Ice Canopy: Ice from the point of view of the submariner.

Friendly Ice: An ice canopy containing many large skylights or other features which permit a submarine to surface. There must be more than ten such features per 30 nautical miles (56 km) along the submarine's track.

Hostile Ice: An ice canopy containing no large skylights or other features which permit a submarine to surface.

Bummock: A downward projection from the underside of the ice canopy; the submerged counterpart of a hummock.

Ice Keel: A downward-projecting ridge on the underside of the ice canopy; the submerged counterpart of a ridge. Ice keels may extend as much as 50 metres below the surface.

Skylight: Thin places in the ice canopy, usually less than 1 metre thick and appearing from below as relatively light, translucent patches in dark surroundings. The undersurface is normally flat. Skylights are termed large if big enough for a submarine to attempt to surface through them (120 metres) or small if not.

Return to Table of Contents

Chapter 2: Ice Observations

This chapter deals with the present ice-observing methodology.

Ice observations are made using electronic aids such as radar, by visual observation or from a combination of both methods. These methods vary as functions of the platform from which the ice observations are made as well as what electronic aid equipment is available.

The emphasis in this manual is on visual ice observations made from aerial- and surface-based platforms. References are made to the use of airborne radar imagery; however, the reader is referred to documents related to the interpretation of radar imagery. (cf. 4 and 5)

Ice observations are dependant on the perspective from which the ice is viewed. Ice can be observed from the aerial perspective using an aircraft or helicopter or from the surface perspective using a vessel or from shore. Each perspective has limitations on the nature and detail of ice observations which can be made and in turn drawn on an ice chart. It is important that the Ice Service Specialist understands these limitations and what aspects of the ice can and cannot be observed from each perspective.

2.1 Aerial Ice Observations

Using aircraft as platforms from which to conduct ice reconnaissance, a nearly synoptic description of ice conditions can be obtained. Large areas of ice can be covered in a relatively short time, using the latest state-of-the-art electronic aids combined with visual observations, where weather conditions and daylight make it possible to see the ice surface.


Photo of first-year ice and grey-white ice underneath
the Laviolette Bridge.
Photo: Jacques Collin © Environment Canada, 2014

However the limitations must be realized. As the observing distance from the aircraft increases, it becomes progressively more difficult to detect changes in the ice surface. Therefore it is necessary to determine the visibility limit, which is the maximum distance from the aircraft at which the Ice Service Specialist can confidently identify and locate ice features. Under normal circumstances, the visibility limit should not exceed 15 nautical miles (25 kilometres) on each side of the aircraft. Ice observations made in the early morning or late afternoon under sunny skies allow for much easier identification of surface features away from the aircraft. In an overcast situation with snow-covered ice, a condition known as flat light will often exist. This condition eliminates shadows and causes ice-surface features to appear insignificant or even invisible. Observing limits will change as a function of altitude and the prevailing horizontal and vertical visibility.

In order to successfully perform ice-reconnaissance duties, the Ice Service Specialist must be able to recognize, identify and record the different characteristics and features which distinguish one ice type from another. Training and experience in ice recognition allows the Ice Service Specialist to identify ice types, concentrations, floe sizes and significant surface features

Aerial observing platforms are usually stable relative to their intended track, but ground speed varies considerably with wind. For this reason, the aircraft position should be plotted on the ice chart with a dot every few minutes.

In the conduct of aerial ice reconnaissance, the Ice Service Specialist employs standard techniques and procedures which are designed to provide the maximum amount of useful, quality-controlled information. Discussion with the participating air crew as to the extent of flight, general area of reconnaissance, close-tactical support requirements and other particulars are routine for each flight. Attendance at pre-flight weather briefings is also normal.

The Ice Service Specialist has available on board the reconnaissance aircraft several useful electronic aids that can be combined, where appropriate, with visual observations. These aids may include an airborne imaging radar and an airborne radiation thermometer (ART).

Airborne Imaging Radar: An imaging radar is the most valuable ice-observing tool. It is presently the only operational source of mapped ice information when the surface becomes obscured by fog or cloud.

An Ice Service Specialist who is fully familiar with the operation and the limitations of the radar system can effectively delineate ice edges and large leads, estimate the total ice concentrations and when used in combination with other sources of information, identify and distinguish many ice types.

2.1.1 Use of Electronic Aids

There are two types of imaging radars that are used for ice reconnaissance. The first type is the Side-Looking Airborne Radar (SLAR), which is a real-aperture system. It differs from most other airborne radars in that the antenna is rigidly fixed to the aircraft and the energy is directed towards either side of the aircraft ground track. Scanning of the area to either side of the ground track is accomplished by the movement of the aircraft in flight. The radar returns are then processed and converted into intensity-modulated traces on cathode ray tubes. This light is used to expose film thus producing a photo radar map of the ground.The signal is also digitized and processed by on-board computers and is transmitted to ships and ground stations in digital format. It then is relayed to the Canadian Ice Service and Canadian Coast Guard Ice Operation Centres.

Imagery may be acquired at 25, 50 or 100 kilometres swath widths on both sides of the aircraft. Generally speaking, the 100 kilometres swath is used when wide aerial coverage is desired. If more detail is needed or the width of a channel being imaged is narrow, a 50 kilometres swath may be specified. Unless otherwise specified, the Side-Looking Airborne Radar is operated at the 100 kilometres swath.

The second type of airborne imaging radar is the Synthetic Aperture Radar (SAR). This radar forms an image by a different process. It uses a relatively short antenna to produce a wide beam. The image is built up by successive scans but the radar also makes use of the Doppler history of the surface being scanned as the aircraft moves forward. As the beam of the radar moves across the surface, changes in position are calculated and this information is used in creating the radar image. The effect is to synthesize a much longer antenna than is physically possible on the Side-Looking Airborne Radar, achieving a constant resolution across the image. This factor, along with a finer resolution, distinguishes the Synthetic Aperture Radar from the Side-Looking Airborne Radar.

The radar image is mainly a function of the return microwave energy which is dependent on the radar system parameters and the surface characteristics. Through practice and experience, radar imagery can be interpreted by studying changes in texture, pattern and tone.

Airborne Radiation Thermometer: The Airborne Radiation Thermometer provides a linear trace of the surface temperature along the flight track directly below the aircraft. Due to the effect of atmospheric moisture on the accuracy of the temperature reading, the system is routinely calibrated over known temperature reference targets, such as melting ice or frazil ice. Its prime application is in monitoring surface temperatures of open water bodies for determining the growth and decay of ice.

2.1.2 Ice Type Identification:

The first tool the Ice Service Specialist should use during any visual observation is the local ice climatology. Although some ice types will look virtually identical at different times of the year, a knowledge of what ice types and features are possible in any given location will greatly simplify the identification process. The Ice Service Specialist should be aware of all ice information for the area from ships, shore stations and scientific parties to further support the ice types under consideration. Previous ice charts and observations should also be referred to in order to maintain the consistency of observations between flights.

Accurate aerial observations require careful examination of the ice surface for subtle features. Although some conditions are very easy to interpret, such as old ice floes in a matrix of grey ice, other conditions require more attention to details. An example of a more complicated ice condition to observe is small floes and ice cakes of old ice within a heavily ridged snow-covered area of thin first-year ice.

Surface topography is one indicator of ice type that can be used in most observing situations. For example, the surface topography of first-year ice is generally rougher than old ice. Old ice floes tend to stand out as smooth rounded areas encased by ridged and rubbled first-year ice in mixed ice-type conditions. Determining whether the ice surface is ridged or rafted will also help determine ice type, since thinner ice will tend to raft rather than ridge. Old ice floes have a higher freeboard than first-year ice and hence will appear to "stick out" of the general ice surface.

Ice colour is another indicator of ice type that can be used when lighting conditions permit and the ice surface is free of snow. Since thin ice types are more transparent, they show the darkness of the water beneath them. As the ice thickens it becomes greyer in appearance. Beyond the thin first-year ice category, the colour differences are negligible and it is no longer possible to distinguish thicker ice types on the basis of colour alone, except for old ice floes. When ice is very thick it becomes more of a blue-white colour. The colour is most apparent during the melt period, but it can be observed at other times.

To distinguish thick first-year ice from second- or multi-year ice, additional surface features (e.g. topography) need to be considered.

This is because there is little difference in colour between the three types, except during the melt period. The melt ponds on thinner ice types become blue-grey, then green-blue and finally black as they continue to melt deeper and thaw holes begin to appear. Their colour remains blue on old ice types unless the floes become very deteriorated.

A complicating factor in winter ice observation is the presence of snow cover on the ice surface. This requires the Ice Service Specialist to pay much closer attention to the orientation and severity of the surface topography, since colour and other surface features are hidden. Visibility limits are often reduced over snow-covered ice, as it becomes difficult for the Ice Service Specialist to detect changes in ice colour or surface roughness.

Visual observation of ice types in summer or melt conditions requires attention to melt patterns. As the snow melts on first-year ice, it produces pools of fresh water very similar to old-ice conditions. These pools initially make the surface of old ice and thick first-year ice appear blue. Unlike first-year ice, old ice has an established drainage pattern at this point and so has fewer melt ponds with small connecting streams.

Despite these guidelines and even with the benefit of much experience, there will be situations where ice types cannot be identified with reasonable confidence. In all such cases, the Ice Service Specialist shall still make an observation to the extent possible and designate all other unknown or unidentified categories with an X designator. A partial observation is better than none at all.

2.1.3 Boundary Placement

The placement of ice boundaries is just as important as the identification of ice types. These boundaries indicate differences in ice conditions that relate to total concentration, floe size, surface features or ice types.

It is important to locate ice boundaries as accurately as possible. Determining the distance from the aircraft to ice edges or other ice features requires a good deal of practice and attention to detail. When beginning a period of visual observation, an Ice Service Specialist should make an attempt to identify a significant land or ice feature which will be evident on radar and ask the radar Ice Service Specialist for the exact distance.

This technique is also useful for experienced Ice Service Specialist when the decision is taken to fly a mission at a higher or lower than normal altitude, as it allows the Ice Service Specialist to quickly orient oneself.

Visibility limits shall be drawn on the chart parallelling the flight track for all sections of the flight where visual observations are made.

The Ice Service Specialist should avoid drawing overly complex ice charts by merging areas of similar ice conditions.

2.1.4 Estimating Ice Concentration:

Observations from airborne platforms allow for a more accurate estimate of ice concentration. An Ice Service Specialist with weather-observing experience will find the procedure of estimating ice cover in tenths quite straightforward. In the higher concentrations (6-10 tenths), it is often easier to estimate how much of the area is ice-free rather than how much is ice-covered.

Table 2.1 provides a visual guide to estimating ice concentrations. The Ice Service Specialist should use judgement in recording ice conditions to the maximum detail that their chart scale will allow.

2.1.5 Chart Production

In an aerial-observing situation, the data collected by visual observation, radar observation and the Airborne Radiation Thermometer are placed on a single chart. This compilation of all data sources allows the Ice Service Specialist to correlate the various information sources and improve accuracy. The resulting chart is the main product of the mission; therefore its accuracy is crucial to a successful mission.

Visual observation of surface ice features is a very accurate means of determining ice type and concentration. However, estimated distances are not as accurate as radar measurements. For this reason, whenever radar and visual observations are to be correlated, edges that are distinct should be taken from radar. Ice type concentration should normally be taken from the visual chart. When available, Airborne Radiation Thermometer data should be included as spot observations.

These figures are examples of actual aerial ice charts produced from an operational flight. Procedures for coding the chart are described in Chapter 3.

2.1.6 Helicopter Observations

An example of a Nares Strait ice chart produced from a helicopter flight on August 21, 2001.
An example of a Nares Strait ice chart produced from a
helicopter flight on August 21, 2001
.

Ice reconnaissance carried out from a helicopter provides a very good opportunity to collect detailed ice information over a fairly large area. Helicopters are used extensively on ships for ice reconnaissance and other purposes. The shipboard Ice Service Specialist should make every effort to accompany as many of these flights as possible.

During helicopter reconnaissance, special attention must be paid to positioning. Most of the helicopters now in use for ice reconnaissance can provide latitude and longitude information. On helicopters equipped with position display navigation systems such as Global positioning system, the Ice Service Specialist can accurately record positions along any particular flight lines.

Where the helicopter does not have positioning equipment on board, the Ice Service Specialist shall constantly dead reckon his position using aircraft heading, speed and elapsed time.

Prior to a flight, the shipboard Ice Service Specialist will normally undertake basic pre-flight planning in consultation with the ship's captain and helicopter pilot. Factors to be considered should include the specific requirements relating to the ship's area of interest, desired flight track/area of coverage, weather conditions (specifically wind speed/ directions), obscuring phenomena and precipitation. Before takeoff the ISS should plot the ship's position, speed and heading on his working chart. During takeoff, he should make note of the time and update the ship's position if required. This information will allow the vessel to be used as a reference point on both the outbound and inbound legs.

In situations where it is necessary to have daily information in near shore waters, a shore-based helicopter reconnaissance program may be established, such as the St. Lawrence River winter ice-reconnaissance program at Quebec City or a similar ice-reconnaissance program at Charlottetown.

The Ice Service Specialist is expected to be aware of and report all significant changes in ice cover, thickness and movement on a daily basis.

In areas normally covered by a shore-based helicopter, each day's chart should be compared to the previous day's chart to ensure consistency and accuracy. As well, the Ice Service Specialist should be aware of all shore-based ice information sources for potential information on fast ice thickness.

2.2 Shipboard Ice Observations

Shipboard Ice Service Specialist are a very important part of the ice-observation network. They provide very detailed ice observations, as well as report characteristics of the ice not collected by aerial reconnaissance methods such as snow depth, ice thickness and ice behaviour.

These detailed observations of the ice are used to make more accurate interpretations of aerial charts as well as for climatological studies. Therefore shipboard Ice Service Specialist should always record ice conditions to the maximum possible detail.

Ice information to be collected should include, but not be limited to:

  • concentration;
  • thickness;
  • topography;
  • ridges per linear mile;
  • depth and surface coverage of snow;
  • melt state;
  • behaviour of the ice (i.e. movement, developing or releasing pressure);
  • ridge heights;
  • iceberg counts; and
  • water temperature

Whenever possible, the Ice Service Specialist should disembark from the ship to the ice surface in order to measure its thickness and snow depth and estimate or measure ridge heights.

The shipboard perspective is similar to the far-range of the aerial perspective as the ice cover is viewed from an extreme angle; this, along with its slow speed, limits the geographic extent of a ship-based ice observation. The low angle perspective of a ship's deck requires special attention to maintain ice observation accuracy. Whereas an aerial observation depends primarily on surface features to determine ice types, a shipboard Ice Service Specialist should normally use ice thickness.

2.2.1 Use of Electronic Aids

The Ice Service Specialist on board the icebreaker has several electronic aids which can provide useful information and be combined with visual observations. The Ice Service Specialist can use the onboard marine surveillance radar to indicate the range and bearing of surface targets such as icebergs or ice edges.

As well, airborne imaging radar data (either Synthetic Aperture Radar or Side-Looking Airborne Radar) can be downloaded to most Coast Guard ships through the use of a downlink receiver and Ice-Vu display software. This will provide the Ice Service Specialist with a source of mapped ice information identical to that available to the Ice Service Specialist on board the ice reconnaissance aircraft. This data is mainly used for navigating the vessel through the ice, but can also help in assessing the general ice conditions in the area. In some cases accurate boundaries and features can be extracted from the imagery for the ice chart.

2.2.2 Ice Type Identification

Accurate estimates of ice thickness can be made by observing ice being turned up along the ship's hull. To help improve accuracy, any known reference point can be used such as the ship's deck rail, the sea bucket or pieces of wood tossed over the side.

To record conditions further away from the vessel, surface topography becomes more important for ice type recognition.

The identification of old ice floes from the ship perspective requires special attention to the surface topography ahead of the vessel. Old ice floes in a mixed field of ice types are often detected by observing a significant difference in freeboard between these floes and other first-year ice floes around them. In many cases there is significant rubble and ridging around these floes; this is caused by the pressure of thinner ice types against the much thicker old ice floe.

The local ice climatology should also be known in order to know what ice types are normal for the area, as well as determining the normal behaviour of the ice.

The Ice Service specialist should also refer to previous ice charts and imagery (if available) collected and/or generated in the days prior to the ship entering the area. This will help to maintain consistency in the observations and help in ice recognition. For example, if the presence of an ice type has been previously reported in the area, the Ice Service Specialist should be looking for that ice type.

2.2.3 Estimating Ice Concentration:

The low observing position from the ship causes separate ice floes to lose their distinction. This can result in over-estimation of the concentration and/or floe size.

In good light conditions, the Ice Service Specialist shall record ice conditions to a distance of no more than 5 nautical miles from the vessel. Experience has indicated that observations beyond 3 nautical miles are very subjective, but this is left at the discretion of the Ice Service Specialist. Attempts should be made to locate an iceberg or another vessel in the 3-5 nautical miles range from the vessel using the ship's marine radar which will help to estimate distances.

Consideration should be given to the fact that ice conditions in the immediate vicinity of the ship are not always representative of those within the accepted observation limits of 3-5 nautical miles. However, the initial assessment of conditions in the near range serves as a good starting point or baseline and can be modified if required as the ship moves through the ice.

Whenever an ice-reconnaissance aircraft is in the area, efforts should be made to speak to the Ice Service Specialist on board. The Ice Service Specialist should try to convey as much information as possible to the aircraft, to help improve the accuracy of the aerial ice charts as they are being generated. Also, an attempt should be made to receive any charts or radar imagery that might be available. The charts or imagery will provide a better overall picture of the ice conditions and will aid in estimating the concentration from the the ship perspective.

It is worth noting that aerial ice charts typically display much larger areas due to their perspective. For this reason, the vessel may find itself in a high-concentration area recorded as a low-concentration area on the aerial chart. It is likely that the ship is in a very localized area of high ice concentration, the limits of which cannot be seen by a shipboard Ice Service Specialist because of the visibility or extent of the ice coverage. When this happens, the Ice Service Specialist should look for signs in the distance to verify the differing concentration, but shall not alter the shipboard chart to comply with the aerial one. Nevertheless, this matter should be discussed with the airborne Ice Service Specialist, if possible.

2.2.4 Chart Production

A daily chart of observed ice conditions shall be produced for the entire area the vessel has travelled while the Ice Service Specialist was on duty. The only exception is when a vessel is in ice-free waters that are not normally subject to sea-ice cover or iceberg intrusion. Data obtained from helicopter reconnaissance flights can either be merged with the daily ice-track chart or plotted as a separate observation. The shipboard charts shall be numbered consecutively from the start of the voyage.

2.2.5 Synoptic Observations

Individual ice observations from ships are an important part of the ice information required to prepare the current ice analysis chart produced daily at the Canadian Ice Service. These observations are used to confirm interpretations of remotely sensed imagery. They also serve as a check on observed charts generated from visual aerial ice reconnaissance.

Marine weather synoptic observations are normally made every 3 hours while a vessel is in transit. The Ice Service Specialist will usually take 3 or 4 observations during the course of their duty day. Synoptic ice observations are taken and recorded using the World Meteorological Organization ice code described in MANMAR (cf. 2). It is important that these observations reach the Canadian Ice Service in a timely manner, so they can be incorporated into the daily ice analysis.

At times when the Ice Service Specialist is engaged in other duties or is off duty, the ship's officers should be encouraged to take, record and transmit marine weather and ice observations in accordance with the codes contained in MANMAR (cf. 2).

2.3 Iceberg Observations

Iceberg observations are acquired in several different ways from the air and from the surface. The method of reporting iceberg observations is the same for both types and the coding procedures are described in chapter 4. Iceberg observations from the air are collected by visual means as well as using airborne radar. This manual will briefly describe visual iceberg observations only. Radar detection of icebergs is dealt with in references 4 and 5 (List of References,p. R-1).

Visual priority flights shall not be undertaken unless visibility along 90% of the planned flight track is forecast to be 15 nautical miles or more. The optimum altitude for visual observation is approximately 1500 feet. Table 2.2 and Table 2.3 illustrate the size, shape and types of icebergs.

2.4 Shore Station Ice Observations

Ice observations from shore are similar to those from ships since the area being observed is limited. The exception exists for ground level locations which are at some height above the area being observed, where the perspective becomes more like a low-level aerial one than one from a ship.

The observer should follow the guidelines previously described for identifying ice types and ice boundaries, as well as estimating ice concentrations. The guidelines for the ground-level or aerial perspective appropriate to the station's location should be used.

2.5 Ice Thickness Observations

Ice thicknesses are measured routinely at selected shore stations, ranging from the Arctic to the Great Lakes. Occasional thickness measurements are obtained from icebreakers. All thickness observations are desirable and should be obtained where and when possible.

These measurements serve to help verify aerial and shipboard observations by providing the exact World Meteorological Organization thickness category at the point of measurement. This data can be used to compare estimates made in the same area at the same time or during future observations. It can also be used to predict future ice thicknesses.

Chapter 6 describes the procedures for coding and reporting ice-thickness observations.

Table 2.1: Diagram of Ice Concentrations from an Aerial Perspective

DiagramIce concentrationDescription
 Diagram of 'Ice Free' - 0/100/10Ice Free
 Diagram of 'Open Water' - less than 1 tenthless than 1/10Open Water
 Diagram of 'Very open drift' - one tenth1/10Very open drift
 Diagram of 'Very open drift' - two tenths2/10Very open drift
 Diagram of 'Very open drift' - three tenths3/10Very open drift
 Diagram of 'Open Drift' - Four tenths4/10Open drift
 Diagram of 'Open Drift' - Five tenths5/10Open drift
 Diagram of 'Open Drift' - Six tenths6/10Open drift
 Diagram of 'Close pack/Drift' - seven tenths7/10Close pack/Drift
 Diagram of 'Close pack /Drift' - eight tenths8/10Close pack/Drift
 Diagram of 'Very close pack' - nine tenths9/10Very close pack
 Diagram of 'Very close pack' - 9+ tenths9+/10Very close pack
 Diagram of 'Compact/Consolidated ice' - ten tenths10/10Compact/Consolidated ice

 

Table 2.2: Iceberg Size

Iceberg typeIceberg SizeHeight above sea surface (meters)Length (meters)Weight (Megatons)
Growler Image of the size comparison of a growler to a personless than 1 metreless than 5 metres0.001
Bergy Bit Image of the size comparison of a bergy bit to a garage1 metre to less than 5 metres5 metres to less than 15 metres> 0.01
Small Berg Image of the size comparison of a small berg to a house5 metres to 15 metres15 metres to 60 metres>0.1
Medium Berg Image of the size comparison of a medium berg to a yacht16 metres to 45 metres61 metres to 120 metres2.0
Large Berg Image of the size comparison of a large berg to an arena46 metres to 75 metres121 metres to 200 metres10.0
Very Large Berg Image of the size comparison of a very large berg to a large buildingGreater than 75 metresGreater than 200 metresGreater than 10.0 metres

 

Table 2.3: Iceberg Shape

ShapeImageAverage height to draft1 ratio
TabularPhoto of tabular iceberg
Photo: © Masterfile Corporation
1:5
Non-Tabular
Photo of a non-tabular iceberg
Photo: © Masterfile Corporation
1:5
Domed
Photo of a domed iceberg
Photo: © Masterfile Corporation
1:4
Pinnacle
Photo of a pinnacle iceberg
Photo: © Masterfile Corporation
1:2
Wedge
Photo of a wedge iceberg
Photo: © Masterfile Corporation
1:5
Drydock
Photo of a drydock iceberg
Photo: © Masterfile Corporation
1:1
Blocky
Photo of a blocky iceberg
Photo: © Masterfile Corporation
1:5

Footnote

Footnote 1

Draft: vertical distance between the waterline and the bottom of the iceberg.

Return to footnote 1

Return to Table of Contents

Chapter 3: Observed Ice Charts

This chapter deals with basic procedures for preparing and transmitting ice charts. Ice charts are of importance to icebreaker captains, commercial shipping interests and fishing vessels to assist them in finding the easiest passage through the ice or to avoid the ice when feasible to do so. The data on the chart is of vital importance to ice forecasters, serving as the basis for:

  • ice hazard warnings
  • preparation of daily ice analysis chart
  • short- and long-range ice forecasts and seasonal outlooks
  • preparation of regional ice charts

 

3.1 Preparation of Ice Charts

Time and care are necessary to prepare ice charts. Details and precision are of the utmost importance.

3.1.1 Drawing Procedures

Ice charts are drawn directly on a computer screen using Geographical Information Systems software. This software has been developed specifically for the Coast Guard to allow precise observation and quick transmission of data.

It is beyond the scope of this manual to describe this particular software in detail. It is sufficient to know the precision of observation is greatly increased by the use and integration of the Global Positioning System (GPS). The usefulness of the data is enhanced by the automatic verification of all coding and final preparation of charts.

Data will generally be transmitted in the form of electronic files and distributed by Canadian Ice Service to clients. Maps of observed data will also be produced by Canadian Ice Service and made publicly available.

3.2 Dissemination of Aerial Ice Charts

Data (in the form of electronic files or charts) is of special importance to the ice forecasters and analysts and ships operating in or near the areas observed during the reconnaissance mission. Files are updated continuously while airborne and sent frequently. Partial files, rough copies and final copies of charts may be sent in-flight to the Canadian Ice Service, the appropriate Coast Guard ice offices and Coast Guard ships as necessary.

After the termination of the reconnaissance mission, the Ice Service Specialist will transmit the completed and corrected data to the Canadian Ice Service for distribution.

3.3 Dissemination of Shipboard Ice Charts

 

An Ice Service Specialist serving on icebreakers equipped with appropriate communication equipment should relay their ice information (even if incomplete) before 1800 UTC to Canadian Ice Service. Upon completion of the duty day, a second transmission is recommended. The data should be sent in the form of an electronic file via cellular phone, landline or satellite link depending on what is practical and available.

If it is not possible to transmit an electronic file, then a map could be printed and send by facsimile.

3.4 The Egg Code

The basic data concerning concentrations, stages of development (age) and form (floe size) of ice are contained in a simple oval form. A maximum of three ice types is described within the oval. This oval and the coding associated with it, are referred to as the "Egg Code". To indicate ice observations interpreted from radar imagery, the oval shall be omitted.

In the following figures and tables where ranges are shown for thickness, floe sizes or other dimensions, a report coinciding with the end point of a range shall be coded as the higher value.

The following is a summary diagram of the Egg Code. This code conforms to international convention and shall be used in coding all visual sea ice and lake ice observations without exception.

Diagram of the components of the egg code: total and partial concentration, stage of development and forms of ice. See description below for details.

The symbols CaCbCc and FaFbFc correspond to Sa Sb Screspectively.

There are some minor additions to the egg code symbology that are Canadian practice. In Canada, to enable the reporting of additional ice classes, especially during freeze-up and break-up, Cd Se and Fe can be used. This should not be a common occurrence.

The following pages describe the specific details and rules for completing each level of information within the egg.

3.4.1 Concentration (C)

Diagram of the egg code indicating the location of concentration of ice. See description below for details.

Total concentration (Ct ) of ice in the area reported in tenths and partial concentrations of thickest (Ca), second thickest (Cb), third thickest (Cc) and fourth thickest (Cd) ice in tenths.

Notes:

  1. Less than 1/10 (i.e. traces) shall not be reported within the oval except to describe open water (see Example 1, section 3.8).
  2. Cd shall only be included when Sd and Seare reported (see Example 2, section 3.8).
  3. When Sd is used and Cd is omitted, Cd equals Ct-(Ca+Cb+Cc) (see Example 3, section 3.8).
  4. When only one ice type is present, the partial concentration shall not be indicated (see Example 4, and Example 5, section 3.8).
  5. When one ice type is present with a trace of a thinner type, only total concentration of the major ice type shall be indicated (see Example 5, section 3.8 ).

3.4.2 Stage of Development (S)

Diagram of the egg code indicating the location of stage of development. See description below for details.

Stage of development of thickest (So), second thickest (Sa), third thickest (Sb) and fourth thickest (Sc) ice and the thinner ice types Sd and Se, of which the concentrations are reported by CaCb Cc Cdrespectively.

Notes:

  1. Reference to thicker ice should be understood to mean older ice and conversely, thinner ice to mean younger ice types.
  2. Ice is designated as Sea, Lake or River Ice depending on where it forms. In Canada, the practice is to use lake-ice coding to report ice in the Great Lakes and the St. Lawrence Seaway. Elsewhere, including the St. Lawrence River east of Montreal, sea-ice coding is used for stages of development.
  3. Sa, Sb and Sc shall have concentrations of at least 1/10, except when Ct is zero (see Example 1, section 3.8).
  4. Reporting of Sa, Sb and Sc should generally be restricted to a maximum of three significant classes. In exceptional cases further classes may be reported as follows:
    • So- Stage of ice development thicker than Sa, but having a concentration less than 1/10 (see Example 6, section 3.8).
    • Sd- Stage of development of the thickest remaining ice types (if more than one type remains). It is the fourth stage present after Sa, Sb and Sc.
    • Se- Shall only be reported when a thinner ice type remains after Sd. Partial concentration of Se is obtained by subtracting partial concentrations (CaCbCcCd) from total concentration (Ct) (see Example 2, section 3.8).
  5. When Se is not present,Sd may be a trace of ice (see Example 6, section 3.8).
  6. Concentration shall not be indicated for So and Se(see Example 2, section 3.8, and Example 6, section 3.8).
  7. Concentration shall not be indicated for Sd when Seis not present (see Example 3, section 3.8, and Example 5, section 3.8).

 

Table 3.1: Coding for Sea-Ice Stages of Development (SoSaSbScSdSe)

DescriptionThicknessCode
New ice< 10 centimetres1
Nilas, Ice rind< 10 centimetres2
Young Ice10 - 30 centimetres3
Grey Ice10 - 15 centimetres4
Grey-white ice15 - 30 centimetres5
First-year ice>= 30 centimetres6
Thin first-year ice30 - 70 centimetres7
First stage thin first-year30 - 50 centimetres8
Second stage thin first-year50 - 70 centimetres9
Medium first-year ice70 - 120 centimetres1·
Thick first-year ice> 120 centimetres4·
Old ice-7·
Second-year ice-8·
Multi-year ice-9·
Ice of land origin- Ice of land origin symbol
Undetermined or unknown-X·

 

Table 3.2: Coding for Lake-Ice Stages of Development (SoSaSbScSdSe)

DescriptionThicknessCode
New lake ice< 5 centimetres1
Thin lake ice5 -15 centimetres4
Medium lake ice15 - 30 centimetres5
Thick lake ice30 -70 centimetres7
Very thick lake ice> 70 centimetres1·

 

Notes for Tables 3.1 and 3.2:

  1. On the horizontal line giving SoSa Sb Sc Sd, only one dot (·) shall be placed to indicate the distinction between classes of ice. Every coded figure to the left of the (·) is understood to have the (·) as part of its code (see Examples 2, 3 and 6, section 3.8).
  2. Codes 3 and 6 shall only appear on Canadian charts if the Ice Service Specialist cannot confidently determine the stages of the ice in the area observed.
  3. Codes 8 and 9 shall only appear when measurements have been taken.
  4. Codes 8·and 9·shall normally appear on Canadian charts only from 01 October to 31 December, but if the Ice Service Specialist is confident of the report, it may be used throughout the year, otherwise 7·is used.
  5. The symbol Ice of land origin symbol shall only be used within the egg and when the concentration of ice of land origin is 1/10 or more.
  6. The symbol X (meaning "undetermined") shall be used to designate stages of development or forms of ice only if it is impossible to specify otherwise.

 

3.4.3 Form of Ice (F)

Diagram of the egg code indicating the location of forms of ice. See description below for details.

Floe Size corresponding to SaSbSc Sd and Se (when Sdand Seare greater than a trace).

Notes

  1. World Meteorological Organization International procedures also permit reporting of Fpand Fs as the primary and secondary forms of all the ice without reference to stage of development.
  2. It is Canadian practice to report FaFb Fc as predominant floe sizes of Sa SbScrespectively. This makes it necessary, when only Sa and Sbare present, that Fa and Fbshall be followed by a dash (-) where Fc would normally appear (see Example 7, section 3.8)

 

Table 3.3: Coding for Forms of Ice (FaFb Fc Fd Fe)

DescriptionWidthCode
Pancake ice-0
Small ice cake, brash ice, agglomerated brash< 2 metres1
Ice cake2 - 20 metres2
Small floe20 - 100 metres3
Medium floe100 - 500 metres4
Big floe500 - 2,000 metres5
Vast floe2 - 10 kilometres6
Giant floe> 10 kilometres7
Fast ice-8
Icebergs, growlers or floebergs-9
Undetermined, unknown or no form-X

 

Notes for Table 3.3

  1. Width refers to the maximum horizontal extent.
  2. At least one code 8 must be used for fast or consolidated ice. Other ice types embedded may retain their floe size (see Example 9, section 3.8).
  3. Occasionally the stage of development of fast ice cannot be determined. The area shall be blackened-in to denote fast ice (see Table 3.9).
  4. New sea ice does not have a definite form; therefore, when this stage of development occurs as Sa, Sb or Sc, the symbol X shall be used to designate floe size (see Example 4, section 3.8).
  5. Floe size is not included for So, Sd and Seif the concentration of these ice types is less than 1/10. Otherwise floe sizes for Sd and Se are optional.
  6. If there is a significant variation in floe sizes in an area containing only one particular ice type, the ISS may enter the applicable floe-size Categories in the lowest part of the oval reserved for floe size. The largest floe-size category shall be put on the left side within the oval, followed by the other applicable floe sizes. In this case, the partial concentrations listed (Ca Cb CcCd) would match the partial concentration of floe sizes, instead of different ice types.

 

3.4.4 Coding and Symbology for Strips and Patches

The Strips and patches symbolsymbol, placed at the bottom of the oval in the section reserved for Form of Ice, indicates that the ice is in strips and patches; the concentration within the strips and patches is represented by C.(see Example 11, section 3.8).

When strips and patches are observed in open-water areas, the symbol shall be placed to denote the position of the strips and patches. If the ice in the strips and patches is of the same composition as that inside an adjacent ice edge, no oval is required. If the ice in the strips and patches is of a different composition, an oval shall be used with an arrow or arrow(s) to the strips-and-patches symbol(s). To avoid confusion, the strip symbol must be included with the total concentration (see Example 10, section 3.8).

In an area where the ice is arranged in strips and patches and the ice floes are medium or greater, the floe size shall be indicated by using two ovals. The floe sizes are indicated as normal in the first oval, with the Strips and patches symbolsymbol placed between the first and second ovals. The Strips and patches symbolsymbol is repeated in the second oval beside the total concentration of the strips and patches (see Example 12a, section 3.8).

An alternate way of reporting the same situation as above:

In an area where the ice is arranged in strips and patches and the ice floes are medium or greater, the floe sizes shall be indicated as normal. Both the total concentration and the concentration within the strips will be placed in the space reserved for Ct, with the Strips and patches symbolsymbol between them. When this option is used, Ca Cb Cc and possibly Cd refer to the total concentration and not the concentration within the strips. For example, Ct can be reported as 2Strips and patches symbol9 meaning the total concentration is 2 tenths with strips of 9 tenths and the partial concentration(s) shall equal 2 tenths (see Example 12b, section 3.8).

In an area of ice where some thicker ice type(s) is (are) embedded as strips and patches, these shall be indicated by the use of two ovals. The overall partial concentrations of the ice types are indicated in the first oval and the concentrations within the strips and patches are indicated in the second oval. The Strips and patches symbolsymbol shall be placed between the two ovals and along with the total concentration in the second oval (see Example 13, section 3.8).

 

3.4.5 Coding for Brash

Diagram of the egg code indicating the location of brash coding. See description below for details.

If 1 tenth or more of brash is present, it will always be Ca .

If brash is present, Sa will always be a dash (-), otherwise the normal table is to be used.

Brash is already indicated in the table as 1, therefore Fa= 1 confirms the dash (-) for Sa.

Four digits (VKMT) shall be added below the oval to indicate the thickness concentration breakdown of the brash that is present. Table 3.4 (below) shows the thickness Categories for agglomerated brash. The breakdown shall be entered going from right (T) to left (V). In the case where there is no thickness for thin but there are entries for medium, thick and very thick a zero (0) shall be placed in the thin column. This also holds true for medium (M) and thick (K) regardless of the combination (see Example 14, to Example 17, section 3.8).

Table 3.4: Thickness Categories for Brash (VKMT)

DescriptionThickness
Very Thick (V)> 4 metres
Thick (K)> 2 - 4 metres
Medium (M)1 - 2 metres
Thin (T)< 1 metres

3.5 Symbols Used on Ice Charts

3.5.1 Symbols for Dynamic Processes

Symbols for Dynamic Processes

ProcessSymbol

Compacting

  1. Slight compacting (optional)
  2. Considerable compacting(optional)
  3. Strong compacting(optional)
 Compacting symbol
Diverging Diverging symbol
Shearing Shearing symbol
Drift Drift symbol
Indicate drift speed in tenths of knots
(e.g. 15 = 1.5 knots)
 Drift symbol

 

3.5.2 Symbols for Openings in the Ice

Symbols for Openings in the Ice

ProcessSymbolDescription
Crack Symbol for cracksThis symbol indicates the presence of cracks in the area.
Crack Symbol for crack at a specific location.This symbol represents a crack at a specific location.
LeadLead symbol
or
Lead symbol
The width in nautical miles may be specified.
Frozen lead Frozen lead symbolThe orientation of the crosslines may be varied to distinguish them from other hatching lines.

 

3.5.3 Symbols for Topographical Features

Symbols for Topographical Features

ProcessSymbolDescription
Ridges/Hummocks

Symbol for Ridges/Hummocks

or

Symbol for Ridges/Hummocks

Optional:

Optional symbol for Ridges/Hummocks

C - Concentration or area coverage in tenths.

f - Frequency in numbers per nautical miles (f is an alternative for C).

h - Mean height expressed in decimetres and included when known.

hx - Maximum height expressed in decimetres and included when known.

Rafting Rafting symbolC: concentration in tenths
Jammed brash barrier Jammed brash barrier symbol 

 

3.5.4 Symbols for Ice Thickness

Symbol for thickness measured in centimetres

tE= thickness measured in centimetres

Symbol for thickness estimated in centimetres

tE= thickness estimated in centimetres

Examples:

Example of ice thickness (measured and estimated in centimetres)

When more than one measurement has been taken, both mean and maximum thicknesses are reported, as shown below:

30/40

 

3.5.5 Coding for Stage of Melting

Stage of melting

Melting symbol

Table 3.5: Coding for Stage of Melting (ms)

DescriptionCoverageCode
No melt-0
Few puddles1-3/101
Many puddles>3/102
Flooded ice-3
Few thaw holes1-3/104
Many thaw holes> 3/105
Dried ice-6
Rotten ice-7
Few frozen puddles-8
All puddles frozen-9
Undetermined or unknown-X

 

3.5.6 Coding and Symbology for Snow Cover

Coding and Symbology for Snow Cover

SymbolDescription
 Snow cover symbol

C - concentration (or area coverage) in tenths

s - snow depth, according to Table 3.6

 Snow depth symbolThe orientation of the symbol with an arrow can show the direction of sastrugi

 

Table 3.6: Coding for Snow Depth (s)

DescriptionCode
no snow0
1- 5 centimetres1
6- 10 centimetres2
11- 20 centimetres3
21- 30 centimetres4
31 -50 centimetres5
51 -75 centimetres6
76- 100 centimetres7
> 100 centimetres8
unknown9

 

3.5.7 Coding and Symbology for Ice of Land Origin

Triangular symbol shown:

Symbol for ice of land origin

nn=number, see following Table 3.7
yy=day of month of sighting

Table 3.7: Number of Bergy Bits/Growlers or Icebergs (nn)

NumberCode
None00
101
202
303
404
505
606
707
808
909
1010
1111
1212
1313
1414
1515
1616
1717
1818
1919
1-920
10-1921
20-2922
30-3923
40-4924
50-9925
100-19926
200-49927
500 or more28
Undetermined99

 

Table 3.8: Symbology for Ice of Land Origin

DescriptionOneMany
Growler Symbol for one growler Symbol of many growlers
Bergy bit Symbol of one bergy bit Symbol for many bergy bits
Iceberg (size unspecified) Symbol for one iceberg of unspecified size Symbol for many icebergs of unspecified size
Small iceberg Symbol for one small iceberg Symbol for many small icebergs
Medium iceberg Symbol for one medium iceberg Symbol for many medium icebergs
Large iceberg Symbol for one large iceberg Symbol for many large icebergs
Very large iceberg Symbol for one very large icebergs Symbol for many very large icebergs
Ice island Symbol for ice island 
Ice of sea origin (floeberg) Symbol for ice of sea origin (floeberg) 
Radar target (suspected berg) Symbol for radar target (suspected berg) 

Notes

Tabular iceberg indicated by adding a horizontal line through any of the symbols as shown in the following example. These symbols can be combined with a number, if exact numbers are known.

Example: Tabular iceberg symbol

For further detail on reporting ice of land origin, see Chapter 4.

 

3.5.8 Symbols for Defining Limits

Symbols for Defining Limits

DescriptionSymbol
Limit of Undercast Limit of Undercast symbol
Limit of Radar Observations Limit of Radar Observations symbol
Limit of Visual Observations Limit of Visual Observations symbol
Observed Edge or Boundary Observed Edge or Boundary symbol
Ice Edge or Boundary from Radar Ice Edge or Boundary from Radar symbol
Estimated Edge or Boundary Estimated Edge or Boundary symbol

 

3.5.9 Supplementary Coding for Radar Observations

Relative Roughness

Lightup to 1/10L
Medium2/10 - 3/10M
Heavy4/10 - 10/10H

Relative Roughness

Note:

Areas showing no radar return shall be indicated NIL ECHO.

3.6 Supplementary Procedures for Indicating Total Concentration

In order to facilitate readability of the chart, ice-covered areas may be hatched according to total ice concentration. The hatching symbology (developed by World Meteorological Organization) may be applied to all areas of ice concentration or only to some of them. Whenever hatching is applied, the hatching symbols as shown in Table 3.9 shall be used. No International Rules are given for the thickness of the hatching lines; the thickness may be the same throughout all hatched areas or may vary in the sense that the thickest lines are used for areas of thicker ice. It is Canadian practice not to hatch ice charts except for total concentrations less than 1/10th.

Table 3.9: World Meteorological Organization Symbols For the Hatching of Total Concentration of Ice

DescriptionHatching
Fast Ice Symbol for fast ice
10/10 Consolidated ice, Compact ice and 9-9+/10
Very close pack/drift ice
 Symbol for consolidated ice
7-8/10 Close pack/drift ice Symbol for 7-8 close packed ice
4-6/10 Open drift ice (Line spacing is twice
that of Close pack/drift ice)
 Symbol for open drift ice
1-3/10 Very open drift ice Symbol for very open drift ice
Open water (less than 1/10 sea ice, no ice
of land origin)
 Symbol for open water
Bergy water (less than 1/10 sea ice may be present
and total ice concentration is less than 1/10)
 Symbol for bergy water
Water with Radar Targets (less than 1/10 sea ice may be present and
total ice concentration is less than 1/10)
 Symbol for water with radar targets
Ice free (no ice present) Symbol for ice free

Note

Presence of new ice can be indicated by the following symbols scattered throughout area affected:

Symbol for presence of new ice symbol

3.7 Colour Coding Ice Charts

3.7.1 Introduction

For several years, the Ice Service Specialists have been applying a colour code to ice information charts for the Canadian Coast Guard operations in the St. Lawrence River and the Gulf of St. Lawrence. This has proven to be quite beneficial to individuals making transportation decisions based on these information products. More recently, we have modified and expanded this colour code for application in all coastal waters of Canada, including the Arctic.

3.7.2 The Colour Code

This colour code is intended to assist navigation decisions in ice infested water. It is loosely based on the concept of a traffic light where green represents proceed, yellow represents caution and red represents danger. The objective of the colour code application is to enable a person to quickly assess general ice conditions. A ship sailing in a given area can easily assess the general ice conditions and hence qualify the difficulty or ease to either navigate through easily, or to reduce speed or to stop the ship.

However, this does not consider the other variables such as winds, currents or ship design which are important considerations in any ice navigation decision. The most detailed ice information continues to reside in the ice egg codes.

3.7.3 How to Interpret the Code

The following text is intended to assist an individual interpret the colour presentation.

Open or Bergy Water

Areas of open water or bergy water are coloured blue.

Blue
Open or bergy water

Presence of Ice

For ice concentration of one tenth or greater, the ice type must be separated into two categories: less than 15 centimetres and greater than 15 centimetres thickness:

Ice Types Thicker than 15 centimetres

The colour for a given ice area will be determined by the total concentration of the ice types thicker than 15 centimetres and is represented by the following list:

Colour code for ice types thicker than 15 centimetres

ColourDescription
 Green1 to 3 tenths of ice > 15 centimetres
 Yellow4 to 6 tenths of ice > 15 centimetres
 Orange7 to 8 tenths of ice > 15 centimetres
 Red9 to 10 tenths of ice > 15 centimetres

 

Presence of Old Ice

The presence of old ice (multi-year ice) is indicated by the colour purple, and is represented by the following list:

PatternDescription
 Dashed linesIndicates the presence of 1 to 4 tenths of old ice
 PurpleIndicates the presence of 5 tenths or more of old ice

 

Presence of Fast Ice

The presence of fast ice, regardless of the thickness is always black or grey.

Black or Grey

 

Ice Types Thinner than 15 centimetres - No Colour Assigned in Background

Ice less than 15 centimetres in thickness is indicated by a star code and the colour of the stars is determined by the predominance between grey ice (10 to 15 centimetres) and new ice (0 to 10 centimetres), and is represented by the following list:

PatternDescription
 Blue starPredominance of ice thinner than 10 centimetres
 Red starPredominance of ice thickness between 10 and 15 centimetres

 

Ice Types Thinner than 15 centimetres - Colour Assigned in Background

Secondary ice types with less than 15 centimetres in thickness are indicated by a star code and the colour of the stars is determined by the predominance between secondary grey ice (10 to 15 centimetres) and secondary new ice (0 to 10 centimetres), and is represented by the following list:

PatternDescription
 Blue Stars with colored backgroundPredominance of secondary ice thinner than 10 centimetres
 Red Stars with colored backgroundPredominance of secondary ice thickness between 10 and 15 centimetres

The star code is placed over top of the background colour. In the case of 9 to 10 tenths of ice (red background) and predominance of ice thickness between 10 and 15 centimetres (red stars), there is only one colour which can be represented: red. The result of red stars on a red background is red.

3.8 Examples of the Use of the Egg Code

3.8.1 Various Ice Type and Concentration Combinations

Example 1

Image of an egg with less than one tenth of ice to show open water; some thick first-year in small floes. See description below for more details.

Description:

Less than one tenth of ice to show open water. Some thick first-year in small floes; new ice is also present and has no floe form.

Example 2

Image of an egg with 9+/10 total ice concentration; 3/10 old ice in small floes; 2/10 thick first-year ice in medium floes; 1/10 thin first-year ice in small floes; 2/10 grey-white ice in small floes. See description below for more details.

Description:

9+/10 total ice concentration. 3/10 old ice in small floes, 2/10 thick first-year ice in medium floes, 1/10 thin first-year ice in small floes, 2/10 grey-white ice in small floes, and the remaining 2/10 is new ice with no floe form.

Example 3

Image of an egg with 8/10 total ice concentration; 3/10 old ice in small floes; 2/10 thick first-year ice in medium floes; 1/10 thin first-year ice in small floes; 2/10 grey-white in small floes.

Description:

8/10 total ice concentration. 3/10 old ice in small floes, 2/10 thick first-year ice in medium floes, 1/10 thin first-year ice in small floes and 2/10 grey-white in small floes.

Example 4

Image of an egg with 6/10 of new ice with no floe form.

Description:

6/10 of new ice with no floe form.

Example 5

Image of an egg with 4/10 of old ice in medium floes; new ice is also present with a concentration of less than 1/10.

Description:

4/10 of old ice in medium floes. New ice is also present with a concentration of less than 1/10.

Example 6

Image of an egg with 5/10 total ice concentration; 2/10 thick first-year ice; 2/10 medium first-year ice; 1/10 thin first-year ice. All in small floes. See description below for more details.

Description:

5/10 total ice concentration. 2/10 thick first-year ice, 2/10 medium first-year ice and 1/10 thin first-year ice. All in small floes. Old ice and grey-white ice with a concentration of less than 1/10 are also present.

Example 7

Image of an egg with 5/10 total ice concentration; 2/10 thin first-year ice in small floes; 3/10 grey ice in medium floes.

Description:

5/10 total ice concentration. 2/10 thin first-year ice in small floes and 3/10 grey ice in medium floes.

Example 8

Image of an egg with 9+/10 total ice concentration; 3/10 old ice in big floes; 4/10 first-year ice in medium floes; 3/10 young ice with floes undetermined. See description below for more details.

Description:

9+/10 total ice concentration. 3/10 old ice in big floes, 4/10 first-year ice in medium floes and 3/10 young ice with floes undetermined. Horizontal lines with no egg shell indicates that data has been interpreted from radar

Example 9

Image of an egg with fast grey ice with 3/10 multi-year ice in small floes embedded.

Description:

Fast grey ice with 3/10 multi-year ice in small floes embedded.

3.8.2 Strips and Patches

Example 10

Image of an egg with open water with strips and patches of old and thick first-year ice in small floes.

Description:

Open water with strips and patches of old and thick first-year ice in small floes.

Example 11

Image of an egg with 3/10 total ice concentration; 2/10 old ice; 1/10 thick first-year ice. All ice is concentrated in strips and patches of 9+/10.

Description:

3/10 total ice concentration. 2/10 old ice and 1/10 thick first-year ice. All ice is concentrated in strips and patches of 9+/10.

Example 12a

Image of an egg with 3/10 total ice concentration in strips and patches of 9+/10; 6/10 old ice in vast floes; 4/10 thick first-year ice in big floes. See description below for more details.

Description:

3/10 total ice concentration in strips and patches of 9+/10. 6/10 old ice in vast floes and 4/10 thick first-year ice in big floes. These floe sizes are significant and warrant the use of two ovals.

Example 12b

Image of two eggs with an alternate way to describe the same conditions: 3/10 total ice concentration in strips and patches of 9+/10; 6/10 old ice in vast floes; 4/10 thick first-year ice in big floes. See description below for more details.

Description:

An alternate way to describe the same conditions with 3/10 total ice concentration in strips and patches of 9+/10. 6/10 old ice in vast floes and 4/10 thick first-year ice in big floes. These floe sizes are indicated because they are significant.

Example 13

Image of two eggs with 9+/10 total ice concentration comprised of 1/10 thick first-year ice; 1/10 medium first-year ice; 8/10 new ice and old ice with a concentration of less than 1/10. See description below for more details.

Description:

9+/10 total ice concentration comprised of 1/10 thick first-year ice, 1/10 medium first-year ice, 8/10 new ice and old ice with a concentration of less than 1/10. The old and thick first-year ice are distributed throughout the area in strips and patches made up of 3/10 old and 7/10 thick first-year ice. All ice types in the second oval must be included in the first oval.

Example 14

Image of an egg with 8/10 total ice concentration; 3/10 of brash; 2/10 grey-white ice in medium floes; 3/10 grey ice in small floes; 1/10 of the brash is medium while 2/10 is thin. See description below for more details.

Description:

8/10 total ice concentration. 3/10 of brash, 2/10 grey-white ice in medium floes, 3/10 grey ice in small floes and 1/10 of the brash is medium while 2/10 is thin. There is no thick or very thick brash present.

3.8.3 Brash

Example 15

Image of an egg with 9/10 total ice concentration; 2/10 brash; 4/10 grey ice in medium floes; 3/10 nilas in small floes. See description below for more details.

Description:

9/10 total ice concentration. 2/10 brash (1/10 very thick brash, 1/10 thick brash and a trace of medium and thin brash), 4/10 grey ice in medium floes and 3/10 nilas in small floes.

Example 16

Image of an egg with 5/10 total ice concentration. See description below for more details.

Description:

5/10 total ice concentration. All brash with 2/10 thick brash, 1/10 medium brash and 2/10 thin brash.

Example 17

Image of an egg with 6/10 total ice concentration; 4/10 brash; 2/10 nilas in small floes. See description below for more details.

Description:

6/10 total ice concentration. 4/10 brash (1/10 medium, 1/10 thick and 2/10 very thick) and 2/10 nilas in small floes.

Return to Table of Contents

Chapter 4: Iceberg Messages

This chapter describes the iceberg information depicted on the observed ice chart as generated from either a ship or an aircraft in a message format.

Since Canada is in the northwestern quadrant of the globe, please note that all latitudes and longitudes are degrees North and West respectively. Also note that all times are in Coordinated Universal Time.

4.1 Iceberg Coding and Message Preparation

An iceberg reporting code has been developed by the Meteorological Service of Canada and International Ice Patrol, to allow for exchange of digital iceberg information and to enable computer-assisted manipulation of volumes of iceberg observations into one complete iceberg analysis. The iceberg code follows standard coding practices and iceberg nomenclature of the World Meteorological Organization and supplements codes that exist in World Meteorological Organization. It provides for the reporting of all iceberg parameters, the area of surveillance and the factors that influence both visual and radar iceberg detection.

Listed below is the basic format for the iceberg message, with the following sections describing each component. Notes referred to in the code descriptions appear in Section 4.3 (following the Iceberg Coding Tables section).

Iceberg Message:

IBXXN CCCC YYGGgg
PPPP PtNrNrNrNr YYMMJJ

00000
QcLaLaLaLaL a LoLoLoLoLo ZGGgg 1CsAAA 2VIVI 3RlRlRlRrRrRr 4DsDsHsHs

11111
(SSSS) (IdIdIdId) CIGGgg LaLaLaLaLa LoLoLoLoLo 01CiSiSh
(1ClLEN 2ClWID 3ClHEI 4ClDRA 5ClDIR 6ClSPE)

22222
(SSSS) CIGGgg LaLaLaLaLa LoLoLoLoLo NtNtDrr nnCiSiSh (nnCiSiSh)

33333
CIGGgg LaLaLaLaLa LoLoLoLoLo LaLaLaLaLa LoLoLoLoLo nnnnD ( nnnnD)

44444
CIGGgg LaLaLaLaLa LoLoLoLoLo (1mamamomo) 2NtNtNtD nnCiSiSh (nnCiSiSh)

55555
(SSSS) CIGGgg LaLaLaLaLa LoLoLoLoLo (1DvDvVvVv) (2NvNvrr)

Note:

Note

Groups 00000 to 55555 can be repeated as often as necessary.

4.1.1 Iceberg Message Header

Sample iceberg message header:

IBXXN CCCC YYGGgg
PPPP PtNrNrNrNr YYMMJJ

This section is mandatory for all iceberg messages.

Table 4.1: Iceberg Message Header

SymbolDescriptionCode Table
IBIndicator for an iceberg message 
XXNationality of iceberg messageNote 1
NFigure to indicate source of iceberg messageNote 2
CCCCInternational call sign for the location from which the iceberg message was transmittedNote 3
YYDay of month that the message was transmitted 
GGHour that the message was transmitted 
ggMinute that the message was transmitted 
PPPP4 figure or 4 letter platform identifierNote 4
Note 13
Note 26
PtPlatform typeTable 4.14
NrNrNrNrConsecutive iceberg message number from this platformNote 5
YYDay of the month that the message beginsNote 6
MMMonth of the year that the message beginsNote 6
JJLast digit of the year that the message beginsNote 6

4.1.2 Track Information

Sample track information message:

00000
QcLaLaLaLaLa LoLoLoLoLo ZGGgg 1CsAAA 2VIVI 3RlRlRlRrRrRr 4DsDsHsHs

This section is mandatory for icebreakers and aircraft. (Note 7, p. 4-13).

Table 4.2: Track Information

SymbolDescriptionCode Table
00000Indicator that track information follows 
QcQuadrant of the Globe (usually 7)Table 4.11
LaLaLaLaLaLatitude in degrees and minutes at the start of each legNote 8
Note 9
LoLoLoLoLoLongitude in degrees and minutes at the start of each legNote 8
Note 9
ZTime indicator 
GGTime in hours at the start of each leg 
ggTime in minutes at the start of each leg 
1Indicator for general sea ice and altitude group 
CsCode for general sea ice distributionTable 4.12
AAAAltitude of platform in hundreds of feet 
2Indicator for visibility group 
VIVIVisibility left of track in nautical milesNote 10
VrVrVisibility right of track in nautical milesNote 10
3Indicator for radar group 
RlRlRlRadar range to left of track in nautical milesNote 10
RrRrRrRadar range to right of track in nautical milesNote 10
4Indicator for wave or swell groupNote 11
DsDsDirection (to nearest 10 degrees) from which is generated the predominant wave or swell 
HsHsHeight of predominant wave or swell in half metres 

4.1.3 Individual Observations

Sample of individual observation message:

11111
(SSSS) (IdIdIdId) CIGGgg LaLaLaLaLa LoLoLoLoLo 01CiSiSh
(1ClLEN 2ClWID 3ClHEI 4ClDRA 5ClDIR 6ClSPE
)

Table 4.3: Individual Observations

SymbolDescriptionCode Table
11111Indicator that iceberg observations by individual position followsNote 12
SSSSOptional group used by Ice Operations Centres and by the offshore industryNote 13
Note 26
IdIdIdIdOptional groups used by offshore industry to report consecutive iceberg numberNote 14
IOptional groups used by offshore industry to indicate iceberg mobilityNote 14
CIConfidence level/Method of observationTable 4.13
Note 15
GGTime in hours that observation was madeNote 16
ggTime in minutes that observation was made 
LaLaLaLaLaLatitude of the individual observation in degrees, minutes and tenths of a
minute
 
LoLoLoLoLoLongitude of the individual observation in degrees, minutes and tenths
of a minute
 
01Indicator for single iceberg report 
CiConcentration of sea ice immediately at the iceberg positionTable 4.10
Note 17
SiSize of icebergTable 4.8
Note 18
ShShape of icebergTable 4.9
Note 18
1ClLEN
2ClWID
3ClHEI
4ClDRA
5ClDIR
6ClSPE

Optional groups to report iceberg length (LEN), width (WID), height
(HEI) and draft (DRA), in whole metres, direction (DIR) of iceberg drift
(toward) in whole degrees and speed (SPE) of iceberg drift in knots and
tenths. The confidence level (Cl), indicates whether these parameters are
measured (4) or estimated (5)
Note 19

4.1.4 Cluster Observations

Sample of cluster observation message:

22222
(SSSS) CIGGgg LaLaLaLaLa LoLoLoLoLo NtNtDrr nnCiSiSh (nnCiSiSh
)

Table 4.4: Cluster Information

SymbolDescriptionCode Table
22222Indicator that iceberg observations by cluster followNote 12
Note 20
SSSSOptional group used by Ice Operations Centres and by the offshore industryNote 13
Note 26
CIConfidence level/Method of observationTable 4.13
Note 15
GGTime in hours that observation was madeNote 16
ggTime in minutes that observation was made 
LaLaLaLaLaLatitude of the centre of the cluster in degrees, minutes and tenths of a minute 
LoLoLoLoLoLongitude of the centre of the cluster in degrees, minutes and tenths of a minute 
NtNtTotal number of icebergs within the cluster, disregarding bergy bits and growlersNote 21
DDistribution of icebergs within the clusterTable 4.15
rrRadius of cluster in nautical miles 
nnNumber of icebergs of each size and shape in the clusterNote 21
CiAverage concentration of sea ice in the clusterTable 4.10
SiSize of icebergs reported in the clusterTable 4.8
Note 21
ShShape of icebergs reported in the clusterTable 4.9
Note 21
nnCiSiShSufficient 5 figure groups to describe the numbers of each size and shape within the clusterNote 21

4.1.5 Grid Observations

Sample of grid observation message:

33333
CIGGgg LaLaLaLaLa LoLoLoLoLo LaLaLaLaLa LoLoLoLoLo nnnnD ( nnnnD
)

Table 4.5: Grid Observations

SymbolDescriptionCode Table
33333Indicator that iceberg observations by grid followNote 22
CIConfidence level/Method of observationTable 4.13
Note 12
GGTime in hours that observation was madeNote 16
ggTime in minutes that observation was made 
LaLaLaLaLaLatitude at the start point of the grid in degrees, minutes and tenths of a minute 
LoLoLoLoLoLongitude at the start point of the grid in degrees, minutes and tenths of a minute 
LaLaLaLaLaLatitude at the end point of the grid in degrees, minutes and tenths of a minute 
LoLoLoLoLoLongitude at the end point of the grid in degrees, minutes and tenths of a minute 
nnnnNumber of icebergs within the gridNote 23
DLocation of the gridTable 4.15
Note 22
nnnnDGroup required if both left and right of track grids reported 

4.1.6 Zone Observations

Sample of zone observation message:

44444
CIGGgg LaLaLaLaLa LoLoLoLoLo (1mamamomo) 2NtNtNtD nnCiSiSh (nnCiSiSh
)

Table 4.6 Zone Observations

SymbolDescriptionCode Table
44444Indicator that iceberg observations by zone followNote 24
CIConfidence level/Method of observationTable 4.13
Note 15
GGTime in hours that observation was madeNote 16
ggTime in minutes that observation was made 
LaLaLaLaLaLatitude at the southwest corner of the zone in degrees, minutes and tenths of a minute 
LoLoLoLoLoLongitude at the start point of the grid in degrees, minutes and tenths of a minute 
1Indicator for optional group to specify non-standard zone 
mamaWhole minutes of latitude 
momoWhole minutes of longitude 
2Indicator for total number of icebergs group 
NtNtNtTotal number of icebergs disregarding bergy bits and growlersNote 21
DDistribution of icebergs within the zoneTable 4.15
nnNumber of icebergs of each size and shape in the zoneNote 21
CiAverage concentration of sea ice in the zoneTable 4.10
SiSize of icebergs reported in the zoneTable 4.8
Note 21
ShShape of icebergs reported in the zoneTable 4.9
Note 21
nnCiSiShSufficient 5 figure groups to describe the numbers of each size and shape within the zoneNote 21

4.1.7 Ship Locations

Sample of ship location message:

55555
(SSSS) CIGGgg LaLaLaLaLa LoLoLoLoLo (1DvDvVvVv) (2NvNvrr
)

Table 4.7 Ship Locations

SymbolDescription
55555Indicator that ship position follow
SSSSOptional ship identifier
CIConfidence level/Method of observation (Code Table 4.13)
GGTime in hours of reported ship location
ggTime in minutes of reported ship location
LaLaLaLaLaLatitude of reported ship/cluster centre location in degrees, minutes and tenths of a minute
LoLoLoLoLoLongitude of reported ship/cluster centre location in degrees, minutes and tenths of a minute
1Indicator for first optional group to specify ship speed and direction
DvDvOptional ship direction (01-36) in tens of degrees
VvVvOptional ship speed in knots
2Indicator for second optional group to specify a cluster of ships
NvNvTotal number of ships within the cluster
rrRadius of cluster in nautical miles

4.1.8 Plain Language Remarks

REMARKS (Note 15, p. 4-15)

END (*Mandatory end of message)

4.2 Iceberg Coding Tables

Table 4.8: Size of Iceberg (Si)

DescriptionHeightLengthCode
Growler< 1 metre< 5 metres1
Bergy Bit1- < 5 metres5- < 15 metres2
Small Iceberg5- 15 metres15-60 metres3
Medium Iceberg16- 45 metres61- 120 metres4
Large Iceberg46- 75 metres121-200 metres5
Very Large Iceberg> 75 metres>200 metres6
Not Specified--7
Radar Target--X

 

Table 4.9: Shape of Iceberg (Sh)

DescriptionCode
Tabular1
Non-Tabular2
Domed3
Pinnacled4
Wedged5
Drydocked6
Blocky7
Ice Island8
Not Specified0
Undetermined (Radar)X

 

Table 4.10: Concentration of Sea Ice (Ci)

DescriptionCode
No Sea Ice0
Trace of Sea Ice/
1/101
2/102
3/103
4/104
5/105
6/106
7/107
8/108
9/10,9+/10 or 10/109
UndeterminedX

 

Table 4.11: Quadrant of the Globe (Qc)

LatitudeLongitudeCode
NorthEast1
SouthEast3
SouthWest5
NorthWest7

 

Table 4.12: Distribution of Sea Ice (Cs)

DescriptionCode
No Sea Ice0
Trace of Sea Ice/
Very Open Drift1
Very Open Drift in strips and patches2
Open Drift3
Open Drift in strips and patches4
Close Drift/Pack5
Very Close Drift/Pack6
Consolidated7
UnderterminedX

 

Table 4.13:Confidence Level/Method of Observation (Cl)

DescriptionCode
Radar position with visual confirmation1
Radar (Side-Looking Airborne Radar/Forward-Looking Airborne Radar) only2
Visual only3
Measured (only used in iceberg dimension)4
Estimated (only used in iceberg dimension)5
Satellite - High Confidence6
Satellite - Medium Confidence7
Satellite - Low Confidence8

Note:

A "Z" found in the Ship Location section of older messages is treated as code 3.

 

Table 4.14: Platform Type (Pt)

DescriptionCode
Fixed wing aircraft1
Helicopter2
Icebreaker including helicopter3
Other ship4
Oil rig5
Shore station6
Satellite7

 

Table 4.15: Iceberg Distribution (D)

DescriptionCode
Evenly (both sides of track)1
Left of track2
Right of track3

 

Table 4.16: Source of Iceberg Message (N)

DescriptionCode
Meteorological Service of Canada/International Ice Patrol1
Icebreaker2
Ice Operation Centre3
Offshore Industry4
Canadian Ice Service / International Ice Patrol5

4.3 Notes on Iceberg Coding Procedures

  1. Nationality of originator of iceberg message is indicated by CN for Canadian and US for American.
  2. To facilitate turn-around of iceberg data, messages are designated by source:
    • Aerial reconnaissance by Meteorological Service of Canada and International Ice Patrol
    • Canadian Coast Guard icebreakers
    • Commercial ships, land stations and miscellaneous reports input by Ice Operations Centres
    • Offshore industry
    • Miscellaneous iceberg reports input by the Canadian Ice Service
  3. When transmitted from or through a land station, CCCC is the four-letter identifier, but when transmitted directly from an icebreaker or an aircraft, CCCC becomes the four-letter or four-figure identifier of the ship or aircraft.
  4. Normally a reconnaissance is conducted from one platform and the PPPP code for the identifier is in brackets e.g., icebreaker Henry Larsen (CGHL), MSC Dash-7 (GCFR) and US Coast Guard C130 (1504). Messages from Ice Operations Centres may be comprised of reports from several commercial ships and PPPP becomes (SHIP) or if the message is an assortment of reports from shore stations PPPP becomes (LAND). Messages from the offshore industry will usually include reports from rigs and supply vessels and PPPP is coded as (RIGG).
  5. Consecutive iceberg message numbers shall commence January 1st each year.
  6. Since reconnaissance missions may extend through two days, YYMMJ refers to the date on which the mission began or in the case of a message from industry or Ice Operations Centres the date of the first sighting.
  7. A track is made up of one or more legs defined by position, time and parameters. There are as many legs (lines of code) as required to describe all turning points or any change of parameters, e.g., general sea-ice description, aircraft altitude, visibility, radar range and sea state. Although complete detail is required to reproduce a plot as if it was drawn by the observer, complicated tracks should be redrawn to give a simpler track with appropriate visibility and radar ranges to outline the area of coverage. Variable parameters could be averaged to keep the message to a reasonable length. The last track line must only contain the latitude, longitude and time parameters.
  8. If a mission starts or ends at a shorebase, the first and last position becomes the international call sign of the shorebase. An aerial mission may start or end at any position. For example, a mission from Iqaluit to observe icebergs in Hudson Strait and then sea ice in Hudson Bay, would end iceberg reporting in western Hudson Strait. In this same example, if the mission re-entered Hudson Strait to continue iceberg reporting, the endpoint of the first iceberg reconnaissance would be joined to this restart point by a straight line with all parameters coded as X's. Track legs over stretches of land may have all parameters coded as X.
  9. Each leg start position is, by default, the end position of any previous leg; consequently, the last line of the track is always position and time. For stationary icebreakers, these two positions are the same.
  10. For icebergs, visibility or radar limits are defined by the distance from the ship or aircraft that the observer feels confident that he/she can see or get a radar return for all small icebergs. This does not preclude the observation and reporting of icebergs beyond these limits. the radar visibility must have a minimum of 2 digits and a maximum of 3 digits on either side.
  11. Experienced Ice Services Specialist may estimate the wave or swell group visually or by radar from an aircraft or report XXXX for "undetermined". Icebreakers should report the group.
  12. The individual-position method of iceberg and target reporting should be used in areas near the iceberg limit, areas of offshore drilling activity, the approaches to the Strait of Belle Isle and in all other areas where icebergs are evenly distributed and their numbers permit. When numbers increase or when icebergs are concentrated in small areas, a combination of cluster and individual methods can be used. When numbers become unmanageable, zones and grids should be incorporated.
  13. Messages from the offshore industry and from Ice Operations Centres consist of iceberg reports from individual sources such as commercial ships, rig supply vessels, land stations, etc. If the iceberg message contains only one individual source, the message is coded with PPPP in the second line of the header information and is coded as the first four letters (or figures) of the call sign of the single source. However, if the iceberg message contains iceberg reports from more than one source, the optional group SSSS is used to indicate the call signs of the individual sources.
  14. The offshore industry usually tracks icebergs through their area of interest. Icebergs entering the area are assigned a consecutive number which is maintained until the iceberg exits from the area. The optional group IdIdIdIdI is used by the offshore industry to code the assigned number of the iceberg and to indicate if the iceberg is freely drifting (D), grounded (G) or is under tow (T).
  15. The degree of confidence in an iceberg's observed position and related parameters is expressed by CI. The highest confidence (Code 1) is a radar position with visual confirmation. There should be an attempt to consolidate visual and radar data to produce high confidence levels. Radar-only targets (Code 2) will not appear in areas visually searched, unless there is some doubt about the visual capability which should be expressed in the REMARKS section.
  16. The time of observation is the time at which an individual iceberg, the centre of a cluster, the southwest corner of a zone or the start point of a grid becomes abeam of the track. Times may be rounded off to the nearest 15 minutes but they must be within the time frame of the track leg from which the observations were made.
  17. The concentration of sea ice is a factor which affects iceberg drift and which provides the user with some degree of confidence in iceberg detection, especially if the detection is made by radar. There shall be an attempt to describe the ice cover to the nearest tenth immediately adjacent to the iceberg. However, when the concentration varies from side to side, the recorded concentration will be an average of the conditions around the iceberg. Open water areas or trails caused by the iceberg will be disregarded.
  18. Sizes refer to the portion of the iceberg above water. If height and length of a berg in metres (m) fall into a different size classification, use the larger size. Dimensions (in kilometres) of a tabular berg or ice island may be indicated beneath the symbol. Iceberg size and shape parameters are important in the process of re-identification of icebergs and as inputs to iceberg deterioration and drift models. These parameters shall be reported along the limit of icebergs, in areas of offshore drilling activity, in the approaches to the Strait of Belle Isle and in all areas where the work load permits. When icebergs are more numerous, shape parameters should be simply tabular or non-tabular. When icebergs become too numerous, use code 7 for unspecified size and code 0 for unspecified shape. X's will only be used for radar information.
  19. The optional groups (1ClLEN 2ClWID 3ClHEI 4ClDRA 5ClDIR 6ClSPE) shall be used when any of the length, width, height, draft, direction and speed iceberg parameters are available. The confidence level in this group shall only be measured (Code 4) or (Code 5).
  20. Accurate determination of the positions and radii of clusters is essential so that the circles do not overlap other clusters, zones or grids, overlap land or extend beyond the applicable radar or visual limit. Normally observations by individual position will not be included inside a cluster. However a visually confirmed iceberg through a hole in the clouds could be included in a radar cluster and in this case the total number of icebergs reported in the cluster would not include the individual iceberg.
  21. If there are no bergy bits or growlers present, nn equals NtNt for clusters or NtNtNt for zones. Si is coded as 7 for not specified and Sh is coded as 0 for not specified. However, when the workload permits, the code allows specifying the numbers of different sizes and shapes within the grid or zone. For example, in a cluster free of sea ice which has 1 very large tabular iceberg, 3 medium icebergs, 5 small icebergs and 2 bergy bits which are all evenly distributed within a radius of 5 nautical miles,NtNtDrr nnCiSiShnnCi SiShnnCiSiShnnCiSiS hwould be coded as: 09110 01061 03040 05030 02020.
  22. Grids are defined by the confidence level (whether radar and visual, radar only or visual only), by two positions along the track, by the visibility or radar limits as coded in the track part of the message and by the iceberg distribution (left of track, right of track or both sides of track). A visual and radar or a visual-only grid extends from the track line to the visibility limit. A radar-only rid extends from the track to the radar limit or if there is a visible limit, the grid extends from the visibility limit to the radar limit. Two lines of code are required to encode both visual and radar grids with the same endpoints. Clusters will not be reported inside grids and normally individual icebergs should be excluded. However, individual icebergs which are considered significant because of ize, shape or other parameters which can assist in reidentification may be positioned inside of the grid. The time assigned to the grid associates it with the correct visibility and/or radar limits coded in the track leg, so it is essential that the time refers to the right leg. Grids will not extend beyond one track leg.
  23. An accurate count of iceberg numbers in grids, clusters and zones is desired. However, when numbers are too large, report an estimate and explain in the REMARKS section.
  24. Zones are areas usually one degree latitude by one degree longitude defined by the latitude and longitude of the southwest corner. The optional group 1mamamomo permits the use of nonstandard zones. Zones should not overlap other zones, grids or clusters, or extend beyond the appropriate visibility or radar limit. As with clusters and grids, individual icebergs should not normally appear in zones.
  25. Factors, such as turbulence, drift angle, precipitation and sea state, that can effect radar; and variable visibilities or breaks in the undercast that effect visual capabilities shall be included.
  26. The platform identifier group PPPP, found in the Iceberg Messae Header, and the optional ship identifier group (SSSS), coded in the observation reports can be extended to contain up to 7 alphanumeric characters.

4.4 Examples of Coded Iceberg Reports

Example of a chart from March 6, 2014 produced by the iceberg patrol. Chart identifies iceberg locations around the Northeast coast of Newfoundland.

Return to Table of Contents

Chapter 5: Ice Analysis Charts

This chapter deals with basic procedures for preparing and transmitting various chart products from the Canadian Ice Service (CIS), operations division. These charts are of importance to a variety of users for many purposes such as strategic planning, climate studies and or tactical vessel management. These products use different variations of the egg code described in Chapter 3. In some cases, scale and map area restrict and limit the use of the complete code.

 

5.1 Daily Ice Analysis Charts

5.1.1 Description

These charts are of importance to icebreaker captains, commercial shipping interests and fishing vessels, to assist them in finding the easiest passage through the ice or to avoid the ice when feasible to do so. The charts are meant to provide ice information for strategic planning for their activities during the next 24 hours.

Please note that there are significant differences between daily ice analysis charts and observed/image analysis charts:

  • Frequency

Daily ice analysis charts are done on a daily basis during the season, whereas image analysis charts are done when images arrive for a particular operational area. Observed charts are generated whenever ice conditions are encountered either from ships, helicopters or aircraft.

  • Detail

The other significant difference resides in the amount of detail on each chart. Observed and image analysis charts have more latitude regarding the amount of detail and information that can be placed on the product. Daily ice analysis charts will have less detail pertaining to ice areas and egg definitions. Consequently, daily ice analysis charts have a more generalized look compared to observed/ image analysis charts.

 

5.1.2 Method of Production

Daily ice analysis charts are computer-generated with the use of mapping and image analysis software. The system allows the forecaster to draw lines and place eggs, symbols, drift arrows, and ship positions.

The forecaster will use a variety of data sources such as National Oceanic and Atmospheric Administration Advanced Very High Resolution Radiometer, Geostationary Operational Environmental Satellite, Special Sensor Microwave/Imager, QUICKSCAT, ENVISAT and particularly RADARSAT, as well as the image analysis charts from these data. The field observation charts from ships, helicopter and aircraft provide ground truthing. However on days when no data is available, or when the image analysis does not coincide with the valid time of the daily ice analysis chart (1800 UTC), the ice model from the Canadian Ice Service can be used to advance ice to the valid time.

The Egg Code

There are some limitations on the use of the Egg Code for daily analysis charts. Later in this chapter, we will specifically outline the significant differences. For a complete version of the Egg Code, please see Chapter 3.

Diagram of the components of the egg code: total and partial concentration, stage of development and forms of ice. See description below for details.

Note: The symbols CaCbCc and FaFbFc correspond to SaSbSc respectively.

Concentration (C)

Total concentration (Ct ) of ice in the area indicated in tenths and partial concentrations of thickest (Ca ), second thickest (Cb ) and third thickest (Cc ). Note that Cd which appears on observation/Synthetic Aperture Radar image analysis charts, will not be indicated on daily ice analysis charts from the Canadian Ice Service.

Diagram of the egg code indicating the location of concentration of ice.  See description below for details.

Notes:

  1. When only one ice type is present, the partial concentration shall not be indicated (see Example 1).
  2. When only a trace of thinner ice is present with thicker ice, only the concentration of the thicker ice is indicated inside the egg; the thinner ice type will show as Sd (see Example 2).
  3. When 2 or 3 ice types are present with more than 1/10 concentration, the partial concentration for each type will show inside the egg (see Example 3).
Stage of Development (S)

Stage of development of thickest (So), second thickest (Sa), third thickest (Sb) and fourth thickest (Sc) ice and the thinner ice type Sd, of which the concentrations are reported by CaCbCc respectively.

Diagram of the egg code indicating the location of stage of development. See description below for details.

Notes:

  1. Reference to thicker ice should be understood to mean older ice and conversely, thinner ice to mean younger ice types.
  2. Ice is designated Sea, Lake or River depending on where it forms. In Canada, the practice is to use the Lake Ice code to report ice in the Great Lakes and the St. Lawrence Seaway. Elsewhere, including the St. Lawrence River east of Montreal, sea ice coding is used for stages of development.
  3. Reporting of SaSband Sc should generally be restricted to a maximum of three significant classes. In exceptional cases further classes may be reported as follows:
  • So- stage of ice development thicker than Sa , but having a concentration less than 1/10 (see Example 4).
  • Sd- stage of development of the thickest remaining ice types. It is the fourth stage present after Sa, Sb and Sc . Partial concentration must be at least 1/10 (see Example 4), except during the freeze-up period when a trace of new ice may be present (see Example 2).
  • Se- this stage of development will not appear on a daily ice analysis chart.

 

Table 5.1: Coding for Sea-Ice Stages of Development (So SaSbScSd)

DescriptionThicknessCode
New ice< 10 centimetres1
Grey ice10 - 15 centimetres4
Grey-white ice15 - 30 centimetres5
First Year ice> 30 centimetres6
Thin first-year ice30 - 70 centimetres7
Medium first-year ice70 - 120 centimetres
Thick first-year ice> 120 centimetres
Old ice 
Second-year ice 
Multi-year ice 
Ice of land origin  Symbol for Ice of land origin
Brash -

 

Table 5.2: Coding for Lake Ice Stages of Development (SoSaSbScSd)

DescriptionThicknessCode
New lake ice< 5 centimetres1
Thin lake ice5 - 15 centimetres4
Medium lake ice15 - 30 centimetres5
Thick lake ice30 - 70 centimetres7
Very thick lake ice30 - 70 centimetres1·

 

Notes:

  1. On the horizontal line giving SoSaSbScSd only one dot (·) shall be placed to indicate the distinction between classes of ice. Every coded figure to the left of the (·) is understood to have the (·) as part of its code (see Examples 4 and 5).
  2. The symbol Symbol for Ice of land origin shall only be used within the egg when the concentration of ice of land origin is 1/10 or more (see Example 12).
  3. Code 8·and 9·shall normally appear on the Canadian Ice Service's daily ice analysis charts from 01 October to 31 December.
  4. Brash ice (-), when present, will always appear as Sa(see Example 11).

 

Form of Ice (F)

Floe Size corresponding to SaSbSc

Diagram of the egg code indicating the location of forms of ice. See description below for details.

Table 5.3: Coding for Form of Ice (FaFbFc)

DescriptionWidthCode
Small ice cake, brash ice< 2 metres1
Ice cake2 - 20 metres2
Small floe20-100 metres3
Medium floe100-500 metres4
Big floe500-2,000 metres5
Vast floe2 - 10 kilometres6
Giant floe> 10 kilometres7
Fast ice 8
Icebergs 9
No form X

 

Notes for Table 5.3:

  1. Width refers to the maximum horizontal extent.
  2. At least one code 8 must be used for fast or consolidated ice. When significant ice types are present and it is important to maintain their floe size, the younger ice type will be coded as fast ice (see Example 5).
  3. Occasionally the stage of development of fast ice cannot be determined. The area shall be blackened-in to denote fast ice. Also when the area in question is very small or difficult to place a label, it can be blackened-in. For areas with a trace of old, second or multi-year ice embedded in fast ice, the area will be shaded-in in grey with an attached label or egg.
  4. New sea ice does not have a definite form, therefore, when this stage of development occurs as SaSbor Sc the symbol X shall be used to designate floe size (See Example 1).
  5. When an area of ice has one particular ice type but varying floe sizes, the basic rule will be to represent the ice type that has the predominant concentration and use the corresponding floe size (see Example 6). An exception would be when there are a few giant old floes in a field of medium old floes (see Example 7).
  6. Pancake floe size (code 0) will not appear on the Canadian Ice Service charts. Since pancake ice floes implies new ice, the standard floe size when dealing with new ice at the Canadian Ice Service is always X.

 

Coding and Symbology for Strips and Patches

The symbol Strips and Patches Symbol, placed at the bottom of the egg in Form of Ice section, indicates that the ice is in strips and patches and that the concentration within the strips and patches is represented by C (see Example 8).

In an area in which the ice is arranged in strips and patches and the ice floes are medium (code 4) or greater, the floe size shall be indicated by using two eggs. The floe sizes are indicated as normal in the first egg with the Strips and Patches Symbol symbol placed between the first and second eggs. The Strips and Patches Symbol symbol is repeated in the second egg beside the total concentration of the strips and patches (see Example 9).

In an area of ice in which some first-year or thicker ice type(s) is/are embedded as strips and patches, the strips and patches shall be indicated by the use of two eggs. The overall partial concentrations of the ice types are indicated in the first egg and the concentration within the strips and patches are indicated in the second egg. The Strips and Patches Symbol symbol shall be placed between the two eggs and along with the total concentration in the second egg (see Example 10). Double eggs will be indicted with a leader line to the polygon in question.

Where there are isolated strips and patches of ice, of less than 1/10 concentration, located outside the main ice areas, the strip (Strips and Patches Symbol) symbol will be placed in the area of these strips. Usually these symbols are used to indicate ice in the final stage of melt.

 

5.1.2.1 Defining Polygons

The parsing of ice areas can be done in one of two ways:

  1. By various ice types;
  2. By concentration.

Note that only solid lines will be used to separate areas of different ice type/concentration (no dash lines).

Ice Type

Mandatory boundaries are required between new, grey, grey-white, first-year and old ice.

Please note that ice codes 2 (nilas ice, ice rind), 3 (young ice), 8 (first stage thin first-year ice) and 9 (second stage thin first-year ice) and X (undetermined or unknown) will not appear on any daily ice analysis charts from the Canadian Ice Service.

For old ice, (7·, 8· and 9·) boundaries are required between areas with concentrations of:

  • No old ice
  • Trace of old ice
  • 1 - 3/10
  • 4 - 6/10
  • 7 - 8/10
  • 9 - 9+/10

old ice (7 · , 8 · and 9· ) with a concentration of 4 tenths or more will be considered predominant.

When two ice types are present in equal concentration, the older/thicker type is considered predominant.

When three or more types are present in equal concentrations, the second oldest is considered predominant.

Total Concentration

In the case of total concentration, mandatory boundaries, shown as solid lines are required between areas of:

  • Open water/bergy water: < 1 tenth
  • Very open drift: 1 to 3 tenths
  • Open drift: 4 to 6 tenths
  • Close pack: 7 to 8 tenths
  • Very close pack: 9 to 9+ tenths
  • Compact or consolidated: 10 tenths

The total concentration is the first determining factor in defining ice boundaries. Partial concentrations of new ice are ignored when first-year or thicker ice is present.

 

5.1.2.2 Floe Size

Mandatory boundaries must also be placed between areas of predominantly medium floes or larger (code 4) and areas of predominantly small floes or smaller (code 3) when 6 tenths of thin first-year or thicker/older ice are present.

 

5.1.2.3 Discretionary boundary

In addition to the guidelines for mandatory boundaries, discretionary boundaries can also be used when sufficient data or knowledge of the ice regime has been verified by up-to-date reconnaissance flight, reports or satellite information. These boundaries are to be maintained on subsequent charts only if there is sufficient knowledge of the location, as provided by these data sources.

Discretionary boundaries should only be used in operationally sensitive areas, namely:

  • Great Lakes: shipping routes
  • Gulf of St. Lawrence: shipping routes
  • Newfoundland: coastal waterway to Botwood
  • Arctic: shipping routes
Ice type to consider:

When considering the use of a discretionary boundary, only first-year and old ice are considered, provided there is sufficient knowledge to supply this additional detail. The exception would be in the Great Lakes, where thick or very thick lake ice and areas of ridging should be considered for discretionary boundaries.

Ice Concentration of ice to consider:

Total ice concentration must be at least "close pack" (7 or 8 tenths of ice). New ice, as usual, is ignored when evaluating the total concentration.

Variance of the concentration to consider:

A discretionary boundary may be used if the partial concentration of the first-year or thicker (thick or very thick lake ice) ice varies by at least 3 tenths in a definable area within a mandatory polygon (see Examples 13 and 14).

 

5.1.2.4 Valid Time

Normally every daily analysis chart generated at the Canadian Ice Service has a valid time of 1800 UTC. The chart thus represents ice conditions at 1800 UTC.

 

5.1.2.5 Corrections and Amendments

When a correction or amendment is made to the chart, the abbreviation CCA or AAA will appear next to "ICE ANALYSIS/ANALYSE DE GLACES" at the top of the legend.

  • A correction is required if an error appears on a chart (examples: Ct indicated 5/10, but should have read 8/10; the ice drift is missing; wrong date for an image in the legend).
  • An amendment is warranted when a significant change in ice conditions in a certain area occurs (examples: Ct was put as 5/10 but a report indicated that the concentration was 9+/10; ice is reported in an area shown as open water).

 

5.1.2.6 Chart Legend

Example of a chart legend for North East Newfoundland waters
Example of Chart Legend

The legend is used on the daily ice analysis charts to describe the region, the valid time and date, what information the chart is based on and any warnings in effect.

The information on the source data is to give the client an idea of what was used to prepare the chart, to give a general level of confidence. Only sources that made a significant contribution to the analysis will be indicated. Where possible, the time and the area covered by that source will be given.

 

5.1.2.7 Deadlines

Deadlines may vary from chart to chart, and from season to season.

  • Transmission

As a general rule, at least one chart should be made ready for transmission from the Canadian Ice Service at 1600 Eastern Standard Time (or Daylight Saving Time). However, in consultation with the Canadian Coast Guard Ice Operations Centre(s), priorities regarding which chart to send out first will be determined on a daily basis, to ensure that the most operationally sensitive chart is first selected for transmission.

  • Data reception and integration

For information received from outside sources (CFR charts, Canadian Coast Guard ship reports, etc.), a minimum of 2.5 hours before the transmission deadline is required to integrate it into the daily ice analysis chart. In most cases when the information arrives late, the forecaster will endeavour to integrate the information, especially if it is operationally sensitive. However, this may cause a delay in the delivery of the chart. The decision to process the information or not, for use in the chart, will be at the discretion of the forecaster in consultation with the Canadian Coast Guard ice operations office.

 

5.1.3 Dissemination of Charts

Upon completion of the analyses, daily ice analysis ice charts are disseminated electronically via a product delivery system. Clients will receive products via e-mail, fax or the internet. The Ice Service Specialist and Canadian Coast Guard clients have a special customised delivery system set up.

 

5.1.4 Symbols Used on Daily Ice Analysis Charts

Symbols for Dynamic Process

Symbol indicating direction and drift speed
Indicates the direction and drift speed (in nautical miles per day) in the general area for the next 24 hours from the valid time of the daily ice analysis chart

Note: The drift arrow gives the direction and the number of nautical miles that ice, within 10 nautical miles of the centre of the arrow, is expected to travel over the next 24 hours. Due to the influence of currents and winds, there can be large differences in the direction and speed of the ice even over areas within close proximity. This drift does not take into account the effect of land on the drift. When the arrow points towards land, there may be an increase in ice concentration and ice pressure along the coast.

Symbols for Defining Limits

DescriptionSymbol
Analysed edge or boundary edge or boundary symbol
Bergy water boundary Bergy water boundary symbol

 

Other Symbols Used

ConditionsSymbolDescription
Ship reportsCGTF I5ZUsed to indicate the latest position and time of a Coast Guard ship (during last 24 hrs).
Bergy water Bergy water symbolSymbol used to indicate bergy water conditions.
Ice-free Ice-free symbolSymbol used to indicate ice-free conditions.
Ice island or Ice island fragment Ice island or Ice island fragment symbolSymbol used to indicate ice island or fragments
Open water Open water symbolStipple pattern used to indicate open water areas (less than 1/10).
Fast ice Fast ice symbolBlackened area representing fast ice.
Strips and patches Strips and patches symbolSymbol used to indicate strips and patches of ice outside the ice edge.

Note: Some symbols may be displaced and have a leader line pointing to its actual location.

5.2 Regional Ice Charts

5.2.1 Description

The Canadian Ice Service (CIS) is responsible for maintaining the historical sea ice record for Canada.  The regional sea ice analyses and charts serve as this record and become part of the national archive.  They are used for a wide variety of purposes; as a strategic marine navigation and transportation planning tool, for climate research, for weather models and input to the Global Digital Sea Ice Data Bank The ice charts are created through the manual analysis of in situ, satellite, and aerial reconnaissance data incorporating meteorological, and ice climatology  parameters as required.

Regional ice charts are produced for the following 5 regions:

  • Eastern Arctic
  • Western Arctic
  • Hudson Bay
  • Great Lakes
  • East Coast of Canada.

A high standard of excellence in the production of the regional analyses must be maintained. In order to maintain the quality and consistency between the analyses, the following guidelines shall be followed.

Frequency

Regional ice analyses and charts represent ice conditions on a specific date. Usually they are prepared weekly, but sometimes biweekly or monthly, depending on the season and the region.

The regional charts are scheduled so they align with the historical climate dates, (+ or – 3 days). The historical dates are weekly starting the first of January each year.

To maintain a consistent record of the start and end of the ice season, the regional analyses for the East Coast and Great Lakes have a fixed start and end date. The dates are chosen based on climatology as the week before first ice and the week after last ice. Regional analyses are produced during these dates, even if the region is Open Water or Ice Free. Arctic charts are produced year-round.

East Coast :

Charts are produced beginning on the Monday that falls between the 9 and the 15 of November, corresponding to the historical date of November 12.  

End charts on the Monday which falls between the 24 and the 30 of August for the historical date of  August 27.

Great Lakes :

Charts are produced beginning on the Monday falling between the 2 and the 8 of November for the historical date of November 5.

End charts on the Monday falling between the 1 and the 7 of June for historical date of  June 4.

 

5.2.2 Method of Production

These charts show generalized ice conditions; they incorporate all available data, usually within three days of the valid date. The main data sources are satellite images. The daily ice analyses can be referenced; however, too much detail clutters the chart and is not useful.  Areas of ice can be combined based on the predominant ice type.

5.2.2.1 The Egg Code

Diagram of the components of the egg code: total and partial concentration, stage of development and forms of ice. See description below for details.

The Egg Code is an international code that describes the ice concentration, stage of development and form. There are specific standards that are used in the Regional charts compared to the image analysis and the daily ice charts.

Concentration (C)

Diagram of the egg code indicating the location of concentration of ice.  See description below for details.

The total concentration (Ct) of ice in the area, and partial concentrations of thickest (Ca), second thickest (Cb) and third thickest (Cc) are indicated in tenths.

Notes:

  1. When only one ice type is present, the partial concentrations, (Ca, Cb Cc), shall not be indicated.
  2. Using 0 (zero), for Ct is not allowed
  3. Only single values allowed for Ct, no ranges.
  4. Cd will not be used.
  5. Double eggs are not allowed.
Stage of Development (S)

Diagram of the egg code indicating the location of stage of development. See description below for details.

Table 5.4: Coding for Sea-Ice Stages of Development (So Sa Sb ScSd)

DescriptionThicknessCode
New ice< 10 centimetres1
Grey ice10 - 15 centimetres4
Grey-white ice15 - 30 centimetres5
First-Year ice> 30 centimetres6
Thin first-year ice30 - 70 centimetres7
Medium first-year ice70 - 120 centimetres1•
Thick first-year ice> 120 centimetres4•
Old ice 7•
Second-year ice 8•
Multi-year ice 9•

 

Table 5.5: Coding for Lake Ice Stages of Development (So Sa Sb ScSd)

DescriptionThicknessCode
New lake ice< 5 centimetres1
Thin lake ice5 - 15 centimetres4
Medium lake ice15 - 30 centimetres5
Thick lake ice30 - 70 centimetres7
Very thick lake ice> 70 centimetres1•

Reporting the stage of development (SOD) should generally be restricted to three significant classes (SaSbSc) and each ice type or Stage of Development will only be used once for each egg.

Notes:

  1. In exceptional cases further classes may be reported as follows:
    • So - used only when the trace of ice is first-year or thicker.
    • Sd  -used when remaining ice type has a concentration of 1/10 or more.
  2. Se - this stage of development will not be used.
  3. ICE / GLACE will not be used.
  4. NO DATA will not be used.
  5. Nilas (code 2) will not be used.
  6. Young Ice (code 3) will not be used.
  7. Generic First-Year Ice (code 6) will not be used.
  8. Brash Ice (“- “ ) will not be reported as a Stage of Development.
  9. Second Year and Multi-Year (8• and 9•)  can be used  between Oct 1 and Dec 31.
  10. Symbol for Ice of land origin (Ice of land Origin) will not be used.
  11.  Ice Islands ( < ) will only be plotted as a non topological point symbol. (see symbols section) i.e. do not outline an Ice Island as a polygon.
Form of Ice (F)

Diagram of the egg code indicating the location of forms of ice. See description below for details.

Table 5.6: Coding for Form of Ice (FaFb Fc)

DescriptionWidthCode
Small ice cake, brash ice< 2 metres1
Small floe20 - 100 metres3
Medium floe100 - 500 metres4
Big floe500 - 2,000 metres5
Vast floe2 - 10 kilometres6
Giant floe> 10 kilometres7
Fast ice 8
No form X

 

Reporting of Form of Ice or Floe Size will be restricted to a maximum of three classes (FaFbFc ) which corresponds to (Sa SbSc).

Floe sizes are not used in climate statistics so there is no need to analyze areas based on floe size alone. Fast Ice (8) is the only floe size information used for climate analysis and products.

Notes:

  1. New Ice is always coded with floe size X (no form).
  2. Pancake ice (code 0) and Ice cakes (code 2), will not be used.
  3. Brash ice (code 1) should only be used when it can be confirmed by visual observations or high resolution imagery.
  4. Ice of Land Origin (code 9) will not be used.

 

5.2.2.2 Symbols Represented on Regional Ice Charts

*Hatching on colour charts can vary.

Symbols for Defining Limits

DescriptionSymbol
Analysed Ice Edge or Boundary Symbol for analysed ice edge or boundary
Bergy Water Boundary Symbol for bergy water boundary

 

Area Symbols

DescriptionSymbol
Bergy Water Symbol for bergy water
Ice-Free Symbol for ice-free
Ice islands Symbol of ice islands
Open WaterSymbol for open water
Stipple pattern used to indicate open water areas.
Fast Ice Symbol for fast ice
Ice Shelves Symbol for ice shelves

Notes:

  1. Strips and patches symbol (Strips and Patches Symbol) will not be used outside of the eggs.
  2. Ice Islands will be represented using the ice island point symbol and only where their position is known either by beacon positioning or where they are visible on imagery and have length greater than 5 kilometres.

 

5.2.2.3 Defining Ice Area Polygons

Areas of ice are analysed using standards based on ice concentration, ice type and if the ice is fast or mobile.

Concentration:

Mandatory boundaries are drawn where the total concentration varies from the following categories:

  • Ice Free
  • Open Water or Bergy Water
  • 1 to 3 tenths: very open drift
  • 4 to 6 tenths : open drift
  • 7 to 8 tenths : close pack
  • 9 to 9+ tenths : very close pack
  • 10/10 : compact/consolidated/fast

Other rules:

Example of two similar egg codes. See description below for details.

Similar areas that contain at least one tenth or more of first-year ice or thicker can be combined if only the new ice is different.

  • Open Water does not require a Stage of Development value.
  • The Iceberg limit will separate Bergy Water from Open Water or Ice Free.  The Iceberg limit will not cross over sea ice polygons/areas.

Boundaries are discretionary if the partial concentration of the First-year or thicker ice types vary by at least 3 tenths. For the Great Lakes use Thick or Very Thick Lake Ice.

Examples: Great Lakes use Thick or Very Thick Lake Ice

Example of egg codes with a partial concentration of first-year or thicker ice types varying by at least 3 tenths.

Example of egg codes with a partial concentration of first-year or thicker ice types varying by at least 3 tenths.

Example of egg codes with a partial concentration of first-year or thicker ice types varying by at least 3 tenths.

Example of egg codes with a partial concentration of first-year or thicker ice types varying by at least 3 tenths.
(lake ice)

Boundaries are discretionary if New Ice of various concentrations are adjacent.

Example of two similar egg codes which could be grouped into one polygon.

These two eggs could be grouped into one polygon.

Stage of development:

Boundaries are mandatory between areas of old ice in the following categories: 

  • no Old Ice
  • trace of Old Ice
  • 1 to 3 tenths
  • 4 to 6 tenths
  • 7 to 8 tenths
  • 9 to 9+ tenths
  • 10/10 or consolidated

Boundaries are mandatory where the stage of development of the predominant ice type varies from New, Grey, Grey-White, Thin First-Year,  Medium First-Year, Thick First-Year and Old ice. Or in the case of lake ice, between New, Thin, Medium, Thick and Very Thick Lake ice.  The stage of development is restricted to 4 significant types (Sa,Sb,Sc,Sd) that have a concentration of one tenth or more. (i.e. no trace amounts are allowed in the Sd position)

  • when two ice types are present in equal concentration, the older/thicker type is considered predominant.
  • when three or more types are present in equal concentrations, the second oldest/thickest is considered predominant.

Other rules:

  • Open Water does not require a Stage of Development value.
  • Old ice should be carefully monitored. A trace of Old ice, with  a floe size of 3 or smaller cannot be detected using satellite imagery.  Therefore care should be taken when drifting traces of Old ice, to ensure that the trace amounts do not unrealistically spread to cover large geographic areas. A trace of Old ice will be reported when it is confirmed by visual observation.
Form of Ice:

Boundaries are mandatory between areas of mobile ice and Fast Ice.  

Other rules:

  • Fast Ice –
    • If the area is too small to be seen on a 8 ½ X 11 paper chart, it does not need to be analysed.
    • Small Areas (< 800 - 1,000 kilometres2) should be shaded black. Thepredominant ice type should be identified using the point symbol (e.g.# 7).  As the ice grows in aerial extent the shaded area will be replaced with an egg.
    • Only one type of First-Year ice, Thick First-Year (4.), Medium First-Year (1.) or Thin First-Year (7) will be used in a Fast Ice area. Other Ice types can be included in the egg.
  • The strips and patches symbols “~”  may be used within the egg when the total concentration of ice is less than 7 tenths.

 

5.2.2.4 Polygon Sizes

The size of a polygon can become problematic if they are too small. The scale of a regional chart is roughly half that of a daily chart. An area should be large enough to be clearly visible on a letter size (8 ½ x 11) paper and allow the placement of a remote egg letter within the polygon. A general rule to follow is that if the polygon is < 1,000 kilometres2 (size of a label letter) it is should be combined with another region.

To determine if an area is large enough, in an IMAGINE viewer, select  VIEW/SCALE and set to 1:4,000,000. If the polygon is not discernable then it is too small and should be amalgamated with the adjacent area.

Examples of minimal polygon sizes for guidance:

Example of a chart with minimal polygon sizes.  See above for description.

Example of a chart with minimal polygon sizes.  See above for description.

Example of a chart with minimal polygon sizes.  See above for description.

 

5.2.3 Quality Control

The regional analyses and charts are quality controlled for data consistency and for international standard reporting practices.

The regional analyses and charts will be amended or corrected after the issue date if significant additional information is made available or if errors are found within the analyses.

The amended or corrected version will be distributed through the Canadian Ice Service normal channels when the amendment or correction is made prior to the next issued regional.  If amendments or corrections are made after the next issued regional the amended or corrected analyses and charts will only be available through the Canadian Ice Service archives and not through the normal distribution channels. 

5.3 Image Analysis Charts

5.3.1 Description

Image analysis charts are tailored products that provide a visual interpretation of the ice conditions primarily from radar imagery that may come from a variety of platforms such as on the ERS, RADARSAT or ENVISAT satellites. The Canadian Ice Service (CIS) receives approximately 3,600 RADARSAT images and 12,000 National Oceanic and Atmospheric Administration Advanced Very High Resolution Radiometer images per year. Operationally significant images are analyzed and the image analysis chart is issued in near-real time (within 4 hours) of data reception at the Canadian Ice Service. The international standard for coding ice information, the Egg Code, is used with some minor modifications. The modifications will be dealt with in the method of production section below, a complete description of the Egg Code can be found in Chapter 3.

This product is primarily intended for the Canadian Coast Guard ice offices and icebreakers to assist them with decision making on ship routings and escorts. The product is used as well by Ice Forecasters to supplement the daily ice analysis and regional analysis charts. Grid-point ice data from the analysis is provided to the Canadian Meteorological Centre weather models, and to ice models at the Canadian Ice Service (CIS) and the Maurice Lamontagne Institute.

The accuracy of an analysis is affected by the spatial resolution of the source data and the processing quality. Here are a few examples:

  • ERS2 - pixel resolution is 25 metres;
  • RADARSAT ScanSAR Wide - pixel resolution is 100 metres;
  • ScanSAR Narrow - pixel resolution is 50 metres;
  • National Oceanic and Atmospheric Administration resolution is approximately 1 kilometre at nadir.

In addition to being able to resolve different ice features, the absolute positional accuracy of the data (geo-coding) will be affected by the accuracy of the satellite orbit information. The Canadian Space Agency estimates that the geometric accuracy of a feature such as an ice edge will be within 630 metres for 100 metres resolution imagery.

 

5.3.2 Method of Production

This chart is a visual interpretation of the Synthetic Aperture Radar imagery by an experienced analyst using a digital image display and vector-drawing tools. The analysis of the ice regime seen on the Synthetic Aperture Radar image is actually a composite of ice signature recognition and support data. Support data sources include the prevailing environmental conditions, ice climatology and coincident ice reconnaissance charts from ships, aircraft or helicopters. Synthetic Aperture Radar analysis charts are tailored to meet the user's requirements. The scale of the chart is not fixed. It will be tailored to the client's geographic area of interest, constrained by the footprint and resolution of the sensor and the need to ensure that the information presented using the egg code is clear, and readable and is issued in a timely fashion. Image analysis charts are issued and archived in digital format, in near-real time, usually within 4 hours of data reception at the Canadian Ice Service.

Defining Polygons

Analysts extract ice concentration, ice type and ice topography from the images, based on tone, texture and spatial context of the ice features (resolution). The extraction of accurate information requires an understanding of ice forms and remote-sensing signatures, as well as access to the meteorological conditions and historic patterns of ice in a specific region. Accuracy may be diminished by poorly processed imagery, artifacts within the imagery or by the effects of moisture on/in the ice.

Areas of different ice conditions are described using elements of the Egg Code on a variable scaled chart. Principally, this code describes the ice in terms of:

  • Ct the total ice concentration expressed to the nearest tenth
  • Ca, Cb, Cc the partial concentrations of up to four main ice types present, to the nearest tenth plus a trace amount.Cd is not used but its value is apparent from the total concentration values.
  • So, Sa, Sb, Sc, Sd the stage of development of sea ice and lake ice. See Table 3.1 and 3.2

Note: Seis not used. X may be coded when ice type is undeterminable.

  • Fa, Fb, Fc the form of the three main ice types present (pancake, brash, small, medium, big, vast, giant floes, strips and patches, or X- indeterminable) depending on the image resolution. See Table 3.3.

Note: Fd and Fe are not used.

  • Brash ice is not coded using the observed VKMT standard. Brash is coded only when there are coincident visual reports to support the signature analysis. If brash is present it will always be Ca. If present Sawill always be a dash (-) and Fa=1.

Diagram of the components of the egg code: total and partial concentration, stage of development and forms of ice. See description below for details.

Mandatory boundaries (solid lines) are drawn:

  • Concentration:
    where the total concentration varies from the following categories:
    • open water or bergy water
    • 1 to 3 tenths
    • 4 to 6 tenths
    • 7 to 8 tenths
    • 9 to 9+ tenths
    • 10/10 or consolidated
  • Stage of Development:
    • the stage of development of the predominant ice type present changes in any way;
    • mandatory boundaries are required between 6/10 and 7/10ths and between 8/10ths and 9/10ths of old ice.
  • Form of ice:
    • the form of the predominant type of ice present changes in any way

Discretionary Boundary lines are drawn for any changes within the Egg Code which could impact on tactical ice operations. For example an area of heavily ridged ice may be separated from level ice.

Estimated Ice Edge Boundaries are used when the analyst may be in doubt about the positional accuracy of the edge because of poor image quality or signature ambiguity.

 

5.3.3 Dissemination of Charts

The image analysis chart product is available for distribution in near-real time or from the archive in raster or grid point format. Delivery methods include the Internet at the Canadian Ice Service website and by subscription service via ftp, email or fax.

 

5.3.4 Symbols Used

Topographical Features

The resolution and imaging mode of the sensor directly affects the analyst's ability to detect surface features. Not all topographical features are analyzed. Below is an accounting of the topographical symbology presently in use.

Relative Roughness

Lightup to 1/10L
Medium2/10 - 3/10M
Heavy4/10 - 10/10H

Symbol for Relative Roughness

In operational areas, relative roughness will be indicated when there are coincident visual reports to support the signature analysis.

Symbols In Use On Image Analysis Charts

DescriptionSymbol
Fast Ice Symbol for Fast Ice
Open Water
(less than 1/10 sea ice, no ice of land origin)
 Symbol for Open Water
Bergy Water
(less than 1/10 sea ice may be present and total ice concentration is less than 1/10)
 Symbol for Bergy Water
Crack
(symbol indicating presence of crack
at a specific location)
 Symbol for Crack
Strips Symbol for Strips
Ice Island Symbol for Ice Island
Ice-free (no ice present) Symbol for Ice-free

 

Symbols for Defining Limits

DescriptionSymbol
Limit of radar observation Symbol for the limit of radar observation
Limit of undercast for AVHRR Symbol for the limit of undercast for AVHRR
Limit of bergy water Symbol for the limit of bergy water
Estimated ice edge Symbol for the estimated ice edge
Ice edge boundary Symbol for the ice edge boundary

5.4 Daily Iceberg Analysis Chart

5.4.1 Description

These charts are important to shipping and fishing vessels as well as the tourism industry. They assist them in determining the limit of all known icebergs on Canada's east coast.

 

5.4.2 Method of Production

Iceberg analysis charts are generated with the use of mapping software (Geographic information system). The system allows the forecaster to model the position of icebergs and targets that were visually or remotely sited up to 40 days prior. The forecaster can use reports from ships, land stations, and radar satellites, but mostly relies on dedicated iceberg flights using fixed wing aircraft. The individual iceberg information is entered into the modelling database, where currents, wind and water temperature and other factors are applied to estimate the iceberg position and size at the time of the chart valid time.

 

5.4.2.1 Valid Time

The Iceberg Analysis charts have a valid time of 1200 UTC. The chart represents the iceberg conditions at 1200 UTC on the date that it is issued.

 

5.4.2.2 Corrections and Amendments

If a correction is warranted, then the chart is re-issued but with the same valid time as the original. There would be nothing on the chart to indicate that it is a correction. Amendments are not issued. If an iceberg is sited outside the iceberg limit, then a bulletin is issued to notify mariners. The chart will not be re-issued.

 

5.4.2.3 Chart Legend

A legend is used on the daily iceberg analysis charts to detail the valid date and time of the chart. When the International Ice Patrol (IIP) is in operation, there is a note that the iceberg limit and the distribution of icebergs in the vicinity of the limit south of 52 North is estimated by the International Ice Patrol. The initials of the forecaster who produced the chart will be in the bottom right corner of the legend.

 

5.4.2.4 Deadlines

The transmission deadline is 1700 UTC.

 

5.4.3 Dissemination of Charts

Daily iceberg analysis charts are disseminated electronically via a product delivery system. Clients may receive the chart via e-mail, fax or the internet.

 

5.4.4 Symbols used on the Daily Iceberg Analysis Charts

Symbols used on the Daily Iceberg Analysis Charts

DescriptionSymbol
Iceberg Limit:
Known icebergs in the Atlantic located landward (north and west) of the iceberg limit.
 Symbol for Iceberg Limit
Iceberg Limit in the Gulf of St Lawrence:
Known icebergs in the Gulf of St Lawrence are located east of this line.
 Symbol for Iceberg Limit in the Gulf of St Lawrence
Sea Ice Limit:
Landward of this line is the location of sea ice of any concentration. Exception: Sea ice in the Gulf of St Lawrence is not usually depicted on the iceberg chart.
 Symbol for Sea Ice Limit
Known Data Limit:
This line depicts the iceberg coverage of the most recent dedicated iceberg flight. This limit is moved southward with the icebergs as they drift. South of this line there is more confidence in the position and number of icebergs than to the north.
 Symbol for Known Data Limit
This number represents the number of icebergs within that degree square. Growlers and/or bergy bits are not included in the count but may be present anywhere within the limit. Symbol for the number of icebergs within that degree square

 

5.4.5 Area of Coverage

The iceberg analysis chart covers icebergs located in waters east and southeast of Newfoundland and Labrador, as well as in the Gulf of St Lawrence. There are two chart extents. The northern extent is used most of the year and shows icebergs between about 45 North and 61 North. The southern extent is used when the International Ice Patrol (IIP) is in operation. It shows icebergs that are between about 40 North and 57 North. On rare occasions when the iceberg limit is south of 40 North, then a text message on the chart will describe the latitude and longitude of the points not seen on the chart.

 

5.4.6 Notes on the Role of the International Ice Patrol (IIP)

The International Ice Patrol was established after the sinking of the Titanic to monitor and report icebergs for Atlantic shipping. While the Canadian Ice Service monitors icebergs year-round, International Ice Patrol usually begins operations when icebergs cross 48º North latitude. This is usually in the late spring. When the International Ice Patrol is in operation they are responsible for determining the iceberg limit south of 52 North. At this time the Canadian Ice Service uses the same iceberg limit as International Ice Patrol for the daily iceberg chart and maintains the limit north of 52 North.

5.5 Colour Coding Ice Charts

Colours are used to enhance ice charts for presentations and briefings. The codes allow users to make a quick assessment of the general ice conditions and to visually follow trends. It is important to remember that the colours alone cannot be used for navigation decisions and that more detailed ice information is contained within the Egg Code. There are four colour codes in use at the Canadian Ice Service, since each code displays the ice in different ways.

 

5.5.1 Standard Canadian Ice Service Colour Code or Ice Services Specialist Colour Code

The Standard Canadian Ice Service Colour code is intended to assist navigation decisions in ice infested waters. It represents the severity of the ice conditions and is somewhat similar to a traffic light. Colours are used to identify ice concentrations of significant ice.

  • Blue and Green represent relatively easy conditions
  • Yellow and Orange indicate caution is needed
  • Red and Purple indicate the more dangerous ice conditions

 

5.5.1.1 Colours used in Standard Canadian Ice Service Colour Code

Total amount of ice thicker than 15 centimetres (grey-white ice or thicker)

Colours used in Standard Canadian Ice Service Colour Code for total amount of ice thicker than 15 centimetres

ColourDescription
 Whiteless than 1/10 of ice >15 centimetres but at least 1 tenth of thinner ice types present
 Green1 to 3 tenths of ice >15 centimetres
 Yellow4 to 6 tenths of ice >15 centimetres
 Orange7 to 8 tenths of ice >15 centimetres
 Red9 to 10 tenths of ice >15 centimetres
 Purple5 to 10 tenths old ice (takes precedence over the other colours)

 

If there are other ice types present, the following symbols would be added to the above colours:

Symbols added to the Standard Canadian Ice Service Colour Code for total amount of ice thicker than 15 centimetres

SymbolsDescription
 Blue star1/10 or more of new ice (less than 10 centimetres). Would not be visible if equal or greater amount of grey ice is present.
 Red star1/10 or more of grey ice (10 to 15 centimetres). Would not be visible if there was also 9 tenths of ice grey-white or thicker.
 Diagonal lines1 to 4 tenths old ice. Would be visible in addition to blue or red stars.

 

In addition, the following colours are used:

Colours used in Standard Canadian Ice Service Colour Code for total amount of ice thicker than 15 centimetres

ColourDescription
 Light blueopen or bergy water (less than 1/10 total ice of any thickness)
 Greyareas of land fast ice of any thickness

 

5.5.2 Internal Quality Assurance Colour Code

The Quality Assurance colour code is used internally to help identify total concentration and thickest ice types within the polygons. Colour is used to identify the stages of ice development and patterns are used to identify ice concentration.

 

5.5.2.1 Colours used in Internal Quality Assurance Colour Code

The pattern of the predominant ice colour is determined by the total concentration of the ice. Total concentration is calculated by adding the partial concentrations. The exception is when first year ice or older is present, any new ice is not included in the calculation of the total concentration.

Patterns used in Internal Quality Assurance Colour Code

PatternIce concentration
 Horizontal lines1 to 3 tenths total concentration
 Vertical lines4 to 6 tenths total concentration
 Diagonal lines7 to 8 tenths
 Solid black9 to 9+ tenths
 Hatched white background10 tenth compacted ice
 Hatcehed grey background10 tenths land fast ice that is coded with an egg

The colour of the predominant ice displays the most common type of ice present. Again, new ice is ignored if first year ice or greater (or older or thicker) is present. The other exception is that old ice is considered predominant if there are 4 tenths or more present.

 

Colours used in Internal Quality Assurance Colour Code

ColourDescription
 YellowNew ice
 OrangeGrey ice
 BlueGrey-white ice
 PinkThin first-year ice
 RedMedium first-year ice or combined all stages of first-year ice
 PurpleThick first-year ice
 BrownOld ice

The second pattern and colour will be the determined by the partial concentration of the second most common ice type. The rules for determining this ice type are:

  • New ice is ignored if first year or thicker ice is present
  • When any old ice is present, it will be used as the second ice type.
  • When 2 ice types have the same concentration, the oldest will be used.
  • When 3 ice types have the same concentration, the middle will be used.

The patterns and colours used for the second ice type are:

 

Colours and Patterns used in Internal Quality Assurance Colour Code

Colour/
Pattern
Description
 Starless than 1 tenth concentration
 Horizontal lines1 to 3 tenths concentration
 Vertical lines4 or 5 or 6 tenths concentration
 YellowNew ice
 OrangeGrey ice
 BlueGrey-white ice
 PinkThin first-year ice
 RedMedium first-year ice or combined all stages of first-year ice
 PurpleThick first-year ice
 GreenOld ice (colour changes from what it is as a predominant colour so that it is more visible)

 

In addition, other colours that may be seen on the charts are:

Colours used in Internal Quality Assurance Colour Code

ColourDescription
 Light blueopen water (less than 1/10 sea ice, no ice of land origin)
 BlueBergy water (less than 1/10 sea ice, and less than 1/10 iceberg concentration).
 Whiteless than 1/10 of ice >15 cm but at least 1 tenth of thinner ice types present
 BlackSmall areas of land fast ice or any thickness.

 

5.5.3 World Meteorological Organization's Colour Code for Concentration

The World Meteorological Organization's colour code for total concentration is an international code that is intended for use when the stage of development is relatively uniform, but concentrations are highly variable (e.g. arctic summer). The legend for the use of the colour code is included on the chart. No colours are used to indicate differences in the ice stage of development.

Table 5.7: World Meteorological Organization's Total Concentration Colour Code

Colour/
Pattern
Total concentration
 BlueIce free
 WhiteIce free (Used at CIS)
 Light blueLess than one tenth (open water)
 Light green1/10 - 3/10 (very open ice)
 Yellow4/10 - 6/10 (open ice)
 Orange7/10 - 8/10 (close ice)
 Red9/10 - 10/10 (very close ice)
 GreyFast ice
? ? ? ?
Undefined ice

Table 5.7.1: Optional World Meteorological Organization's Total Concentration Colour Code

ColourTotal concentration
 Light pink7/10-10/10 new ice
 Pink9/10-10/10 nilas, grey ice (mainly on leads)

*Areas of "No Information" are annotated accordingly

 

Table 5.8: World Meteorological Organization's Total Concentration Colour Code for Lake Ice

Colour/
Pattern
Description
 WhiteIce Free
 Light blueLess than one tenth (open water)
 Light green1/10 - 3/10 (very open ice)
 Yellow4/10 - 6/10 (open ice)
 Orange7/10 - 8/10 (close ice)
 Red9/10 - 10/10 (very close ice)
 GreyFast Ice of Unspecified Stage of Development
? ? ? ?
Undefined Ice

*Areas of "No Information" are annotated accordingly

 

5.5.4 World Meteorological Organization's Colour Code for Stage of Development

The World Meteorological Organization's colour code for stage of development is an international code that is intended for use when the concentration is relatively uniform, but the stage of development is highly variable (e.g. Atlantic winter). The legend for the use of the colour code is included on the chart. No colours are used to indicate differences in the concentration of the ice.

Table 5.9: World Meteorological Organization's Stage of Development Colour Code

Colour/
Pattern
Stage of DevelopmentThickness
 BlueIce Free 
 WhiteIce free (Used at CIS) 
 Light blue< 1/10 Ice (Open Water) 
 Light purpleNew Ice< 10 centimetres
 PurpleGrey Ice10 - 15 centimetres
 PinkGrey-white Ice15 - 30 centimetres
 YellowFirst-year Ice>= 30 centimetres
 Light greenThin First-year Ice30 - 70 centimetres
 GreenMedium First-year Ice70 - 120 centimetres
 Dark GreenThick First-year Ice> 120 centimetres
 Dark orangeOld Ice 
 OrangeSecond-year Ice 
 RedMulti-year Ice 
 GreyFast Ice of Unspecified Stage of Development 
? ? ? ?
Undefined Ice 
White with red triangle fill
Drifting Ice of Land Origin (icebergs) 

 

Table 5.10: World Meteorological Organization's Stage of Development Colour Code for Lake Ice

Colour/
Pattern
Stage of DevelopmentThickness
 WhiteIce Free 
 Light blueIce of Unspecified Stage of Development (open water) 
 Light purpleNew Lake Ice< 5 centimetres
 PurpleThin Lake Ice5 - 15 centimetres
 PinkMedium Lake Ice15 - 30 centimetres
 Light greenThick Lake Ice30 - 70 centimetres
 GreenVery Thick Lake Ice> 70 centimetres
 GreyFast Ice of Unspecified Stage of Development 
? ? ? ?
Undefined Ice 

5.6 Examples of the Use of the Egg Code

Example 1

Image of an egg with 6/10 of new ice with no form. See description below for details.

Description:

6/10 of new ice with no form. Note that there is no partial concentration when only one ice type is represented in the egg.

Example 2

Image of an egg with 4/10 of old ice in medium floes; new ice with a concentration of less than 1/10. See description below for details.

Description:

4/10 of old ice in medium floes. New ice is also present with a concentration of less than 1/10.

Example 3

Image of an egg with 6/10 total ice concentration; 2/10 thin first-year ice; 4/10 grey-white ice in medium floes. See description below for details.

Description:

6/10 total ice concentration. 2/10 thin first-year ice and 4/10 grey-white ice in medium floes. If more than one ice type is present, the partial concentration of each ice type must be indicated.

Example 4

Image of an egg with 7/10 total ice concentration; 3/10 thick first-year ice; 2/10 medium first-year ice; 1/10 thin first-year ice, all in small floes; <1/10 of old ice; 1/10 of grey-white ice. See description below for details.

Description:

7/10 total ice concentration. 3/10 thick first-year ice, 2/10 medium first-year ice and 1/10 thin first-year ice, all in small floes. Note also the presence of old ice with a concentration of less than 1/10, and 1/10 of grey-white ice.

Example 5

Image of an egg with fast ice composed of grey ice with 3/10 of embedded multi-year ice in small floes. See description below for details.

Description:

Fast ice composed of grey ice with 3/10 of embedded multi-year ice in small floes.

Example 6

Image of an egg with 9+/10 total ice concentration; 2/10 thick first-year ice in vast floes; 2/10 thick first-year ice in big floes; 6/10 thick first-year ice in medium floes. See description below for details.

Description:

9+/10 total ice concentration. 2/10 thick first-year ice in vast floes, 2/10 thick first-year ice in big floes, and 6/10 thick first-year ice in medium floes. Since 6/10 of the thick first-year ice is in medium floes it becomes the representative floe size.

Example 7

Image of an egg with 9+/10 total ice concentration; 3/10 old ice of giant floes; 7/10 old ice of medium floes. See description below for details.

Description:

9+/10 total ice concentration. 3/10 old ice of giant floes and 7/10 old ice of medium floes.

5.6.1 Strips and Patches

Example 8

Image of an egg with 3/10 total ice concentration;  2/10 old ice; 1/10 thick first-year ice. All ice is concentrated in strips and patches of 9+/10. See description below for details.

Description:

3/10 total ice concentration. 2/10 old ice and 1/10 thick first-year ice. All ice is concentrated in strips and patches of 9+/10. Floe sizes are code 3 or less.

Example 9

Image of an egg with 3/10 total ice concentration in strips and patches of 9+/10; 6/10 old ice in vast floes; 4/10 thick first-year ice in big floes. See description below for details.

Description:

3/10 total ice concentration in strips and patches of 9+/10. 6/10 old ice in vast floes and 4/10 thick first-year ice in big floes. These floe sizes are significant and warrant the use of two ovals.

Example 10

Image of an egg with 9+/10 total ice concentration; 1/10 thick first-year ice; 1/10 medium first-year ice; 8/10 new ice; <1/10 old ice. See description below for details.

Description:

9+/10 total ice concentration comprised of 1/10 thick first-year ice, 1/10 medium first-year ice, 8/10 new ice and old ice with a concentration of less than 1/10. The old and thick first-year ice are distributed throughout the area in strips and patches made up of 3/10 old and 7/10 thick first-year ice. All ice types in the second oval must be included in the first oval.

Example 11

Image of an egg with 6/10 total ice concentration; 4/10 brash ice; 2/10 new ice with no form. See description below for details.

Description:

6/10 total ice concentration. 4/10 brash and 2/10 new ice with no form.

Example 12

Image of an egg with 9+/10 total ice concentration; 1/10 of ice of land origin with floe size of 9 (icebergs); 5/10 thin first-year ice in big floes; 4/10 grey-white ice in medium floes. See description below for details.

Description:

9+/10 total ice concentration. 1/10 of ice of land origin with floe size of 9 (icebergs). 5/10 thin first-year ice in big floes and 4/10 grey-white ice in medium floes.

Example 13

Image of two eggs with a discretionary boundary due to the varied concentration of at least 3/10 of thin first-year ice. See description below for details.

Description:

A discretionary boundary could be placed between these two eggs since the concentration of thin first-year ice varies by at least 3 tenths.

Example 14

Image of two eggs with a discretionary boundary due to the varied partial concentration of at least 3/10 of thick and medium first-year ice. See description below for details.

Description:

A discretionary boundary could be placed between these two eggs since the partial concentrations of thick and medium first-year ice varies by at least 3 tenths.

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Chapter 6: Ice Thickness Measurements and Reports

This chapter deals with the measurement and reporting of ice thickness and snow depth. The depth of snow is important to know because it has a direct bearing on the ice thickness due to it's insulating qualities. These measurements are important operationally since they provide a means to estimate the general thickness of the ice cover around the area. They are also important climatological records that users need for ice modeling, building infrastructures and, most recently, studies in climate change. Annual data summaries are produced from these measurements.

The observer shall ensure that the site selected has a depth of water greater than the maximum ice thickness expected for the year. The ice thickness and snow depth shall be measured, as near as practicable, at the same location throughout the ice season, and from one season to the next. The site should be on undeformed (level) and undisturbed ice. When the auger is used, a new hole shall be drilled for each measurement made in order to obtain the thickness of the entire ice layer. If a tidal crack is a permanent feature at the station, the site selected should be slightly seaward of the crack.

 

6.1 Weekly Ice Thickness Reports

Weekly reports are used in near real-time as validation of fast ice growth and to estimate the rate of growth of drifting sea ice. The reports are to be forwarded to a designated collection station on the meteorological communication system, where they are to be entered on the circuit in bulletins under the heading "ITCN01"with the collection station's identifier. MANTRANS (cf. 3) gives a listing of ITCN bulletin headings, including the stations contained in the bulletins and prescribes the relays which provide the desired distribution.

The weekly ice thickness and snow depth measurements are coded as follows:

ITCN01 CXXX YYGGgg
(CXXX) YYItI tIt StS tWtd

Table 6.1: Weekly Ice Thickness Message Heading

SymbolDescription
ITCN01Message Identifier
CXXXTransmission station identifier
YYDay of month of message transmission
GGHour of message transmission
ggMinute of message transmission

 

Table 6.2: Weekly Ice Thickness Message Body

SymbolDescriptionCode Table
CXXXObservation station identifier(if different than transmission station) 
YYDay of month of measurement 
ItI tItIce thickness in whole centimetres 
StS tAverage depth of snow in whole centimetres at measurement site 
TSurface topography6.3
WtCracks and leads6.4
dMeasurement method used6.5

 

Table 6.3: Surface Topography (T)

SymbolConcentrationCode
Smooth 0
Rafted0 - 1/101
2/10 - 3/102
4/10 - 10/103
Ridged0 - 1/104
2/10 - 3/105
4/10 - 10/106
Hummocked0 - 1/107
2/10 - 3/108
4/10 - 10/109

 

Table 6.4: Cracks and Leads (Wt)

DescriptionCode
No cracks or leads0
Few Cracks1
Numerous cracks2
Few leads3
Numerous leads4

 

Table 6.5: Measurement Method Used (d)

DescriptionCode
Visually0
Ice Auger Kit1
Hot Wire2
Other Means3

Ice Service Specialist measuring ice thickness.
Ice Service Specialist measuring ice thickness.
Photo: Jan-Andrej Skopalik © Environment Canada, 2013

6.2 Ice Thickness Monthly Report

Weekly ice thickness measurements are recorded on Form 0063-2317. Figure 6.1 ("Ice Thickness Form 0063-2317", p. 6-7) shows an example of a completed form. The completed forms constitute the official record of ice thickness and snow depth reports from network stations. The Officer-In-Charge (OIC) is responsible for ensuring that each form has been carefully checked and signed by himself or his/her deputy. This signature is a certification of the accuracy and completeness of the record.

The form shall be forwarded by mail to the Canadian Ice Service at the end of each month. One copy should be retained for station files. One form should be used for each month's observations.

The station name in full, the month and year shall be entered neatly on each sheet in the appropriate spaces provided at the top of the form.

The form has four (4) categories of information to be entered:

  • measurement site
  • measurements
  • leads
  • remarks

Table 6.6: Ice Thickness Monthly Report

Item #ItemDescription
1Measurement SiteThe bearing and distance from a significant landmark and report any change of the site, should a change become necessary
2aDate of MeasurementThe date (a two-figure number) when the ice measurement is taken
2bIce ThicknessMeasured ice thickness to the nearest whole centimetre
2cDepth of SnowAverage snow depth to the nearest whole centimetre
2dSurface TopographySurface features at the measurement site and seaward (Table 7.3)
2eCracks/LeadsThe presence and orientation of cracks and leads (Table 7.4)
2fMethod UsedThe method used to measure or estiamte the ice thickness (Table 7.5)
2gTransmitted by MessageY (yes) or N (no) whether or not the weekly report was transmitted
3LeadsThe presence and when possible the location orientation, length and width (in metres or kilometres) of leads shall be noted
4RemarksAdditional information (include the date ice first appears and the date the ice is unsafe for measurement)

6.3 Examples of Ice Thickness Reports

Example 1

ITCN01 CYFB 072200
07112 15611

Heading
ITCN01 CYFB 072200
ITCN01 message identifier
CYFB station identifier (Iqaluit)
072200 time of filing report for transmission was 7th day of the month at 2200UTC

Body
07112 15611
07 date of measurement was 7th day of the month
112 ice thickness is 112 centimetres
15 average depth of snow is 15 centimetres at measurement site
6 surface topography = 4/10 - 10/10 ridging
1 few cracks
1 measurement made with ice auger kit

Example 2

ITCN01 CYVN 072100\
07095 08401

Heading
ITCN01 CYVN 072100
ITCN01 message identifier
CYVN station identifier (Cape Dyer)
072100 time of filing report for transmission was 7th day of the month at 2100UTC

Body
07095 08401
07 date of measurement was 7th day of the month
095 ice thickness is 95 centimetres
08 average depth of snow is 8 centimetres at measurement site
4 surface topography = 0 - 1/10 ridging
0 no cracks or leads
1 measurement made with ice auger kit

The above examples would be assembled into a bulletin by YFB, the designated collection station, in the following form:

ITCN01 CYFB 072230
YFB 07112 15611
YVN 07095 08401

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