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Manual of Ice (MANICE)

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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