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Interpreting Ice Charts

Canadian Ice Service 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.

1.0 Open or Bergy Water

Areas of open water or bergy water are coloured blue.

Blue

Open or bergy water

2.0 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:

2.1 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:

ColourDescription
 Whiteless than 1/10 of ice >15 cm but at least 1 tenth of thinner ice types present
 Green1 to 3 tenths of ice >15 cm
 Yellow4 to 6 tenths of ice >15 cm
 Orange7 to 8 tenths of ice >15 cm
 Red9 to 10 tenths of ice >15 cm
 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:

SymbolsDescription
 Blue star1/10 or more of new ice (less than 10 cm). 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 cm). Would not be visible if there was also 9 tenths of ice grey-white or thicker.
 Purple diagonal lines1 to 4 tenths old ice. Would be visible in addition to blue or red stars.

 

2.1.1 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:

SymbolsDescription
 Dashed LinesIndicates the presence of 1 to 4 tenths of old ice
 PurpleIndicates the presence of 5 tenths or more of old ice

 

2.1.2 Presence of Fast Ice

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

Fast ice or Fast ice

 

2.2 Ice Types Thinner than 15 centimetres

2.2.1 No Colour Assigned in Background

Ice with 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:

Symbols Description
 Blue StarsPredominance of ice thinner than 10 centimetres 
 Red StarsPredominance of ice thickness between 10 and 15 centimetres

 

2.2.2 Colour Assigned in Background

Ice 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 grey ice (10 to 15 centimetres) and new ice (0 to 10 centimetres), and is represented by the following list:

SymbolsDescription
 Blue Stars with colored backgroundPredominance of ice thinner than 10 centimetres 
 Red Stars with colored backgroundPredominance of 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.

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