Manice - Chapter 5
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 CIS, since each code displays the ice in different ways.
5.5.1 Standard CIS Colour Code or ISS Colour Code
The Standard CIS 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 CIS Colour Code
Total amount of ice thicker than 15 cm (grey-white ice or thicker)
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(white) less than 1/10 of ice >15 cm but at least 1 tenth of thinner ice types present |
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(green) 1 to 3 tenths of ice >15 cm |
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(yellow) 4 to 6 tenths of ice >15 cm |
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(orange) 7 to 8 tenths of ice >15 cm |
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(red) 9 to 10 tenths of ice >15 cm |
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(purple) 5 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 |
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(blue star) 1/10 or more of new ice (less than 10 cm). Would not be visible if equal or greater amount of grey ice is present. |
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(red star) 1/10 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. |
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(purple diagonal dashed lines) 1 to 4 tenths old ice. Would be visible in addition to blue or red stars. |
| In addition, the following colours are used: |
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(light blue) open or bergy water (less than 1/10 total ice of any thickness) |
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(grey or black) areas of land fast ice of any thickness |
5.5.2 Internal Quality Assurance (QA) Colour Code
The QA 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 QA 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.
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horizontal lines |
1 to 3 tenths total concentration |
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vertical lines |
4 to 6 tenths total concentration |
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diagonal lines |
7 to 8 tenths |
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solid colour |
9 to 9+ tenths |
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hatched white background |
10 tenth compacted ice |
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hatched grey background |
10 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.
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(yellow) New ice |
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(orange) Grey ice |
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(blue) Grey-white ice |
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(pink) Thin first-year ice |
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(red) Medium first-year ice or combined all stages of first-year ice |
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(purple)Thick first-year ice |
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(brown) Old 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:
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stars |
less than 1 tenth concentration |
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horizontal lines |
1 to 3 tenths concentration |
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vertical lines |
4 or 5 or 6 tenths concentration |
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(yellow) |
New ice |
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(orange) |
Grey ice |
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(blue) |
Grey-white ice |
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(pink) |
Thin first-year ice |
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(red) |
Medium first-year ice or combined all stages of first-year ice |
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(purple) |
Thick first-year ice |
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(green) | Old 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: |
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(light blue) |
open water (less than 1/10 sea ice, no ice of land origin) |
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(medium blue) |
Bergy water (less than 1/10 sea ice, and less than 1/10 iceberg concentration). |
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(white) |
less than 1/10 of ice >15 cm but at least 1 tenth of thinner ice types present |
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(black) |
Small areas of land fast ice or any thickness. |
5.5.3 WMO Colour Code for Concentration
The WMO 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 5.4: WMO Total Concentration Colour Code
| Colour |
RGB colour model |
Total concentration |
| Alternate |
Used at CIS |
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000-100-255 |
Ice free |
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150-200-255 |
Less than one tenth (open water) |
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140-255-160 |
1/10 - 3/10 |
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255-255-000 |
4/10 - 6/10 |
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255-125-007 |
7/10 - 8/10 |
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255-000-000 |
9/10 - 10/10 |
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150-150-150 |
Fast ice |
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255-255-255 |
Undefined ice (unknown type and amount) |
| Optional |
| |
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255-175-255 |
7/10 - 10/10 new ice |
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255-100-2555 |
9/10 - 10/10 nilas or grey ice (mainly on leads) |
| Areas of No Information are annotated accordingly |
Table 5.5: WMO Total Concentration Colour Code for Lake Ice
| Colour |
Description |
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Ice Free |
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< 1 Tenth Ice |
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1 - 3 Tenths Ice |
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4 - 6 Tenths Ice/td>
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7 - 8 Tenths Ice |
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9 - 10 Tenths Ice |
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Fast Ice of Unspecified Stage of Development |
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Undefined ice |
| Areas of No Information are annotated accordingly |
5.5.4 WMO Colour Code for Stage of Development
The WMO 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 5.6: WMO Stage of Development Colour Code
| Colour |
RGB colour model |
Stage of Development |
| Alternate |
Used at CIS |
|
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000-100-255 |
Ice free |
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150-200-255 |
≪ 1/10 Ice (open water) |
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240-210-250 |
New Ice |
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135-060-215 |
Grey Ice |
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220-080-235 |
Grey-White Ice |
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255-255-000 |
First-Year Ice |
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155-210-000 |
Thin First Year Ice |
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00-200-020 |
Medium First Year Ice |
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000-120-000 |
Thick First Year Ice |
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180-100-050 |
Old Ice |
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255-120-010 |
Second-Year Ice |
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200-000-000 |
Multi-Year Ice |
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150-150-150 |
Fast Ice of Unspecified Stage of Development |
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255-255-255 |
Ice of Undefined Stage of Development |
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255-255-255 |
Drifting Ice of Land Origin (Icebergs) |
Table 5.7: WMO Stage of Development Colour Code - Lake Ice
| Colour |
Description |
Thickness |
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Ice Free |
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Ice of Unspecified Stage of Development (open water) |
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New Lake Ice |
< 5 cm |
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Thin Lake Ice |
5 - 15 cm |
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Medium Lake Ice |
15 - 30 cm |
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Thick Lake Ice |
30 - 70 cm |
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Very Thick Lake Ice |
> 70 cm |
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Fast Ice of Unspecified Stage of Development |
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Undefined ice |
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