Manice - Chapter 5
5.2 Regional Ice Charts
5.2.1 Description
Regional ice analysis charts are considered to represent ice conditions on a specific date. They are prepared weekly, bimonthly or monthly, depending on the season and the region. They provide information on ice conditions for planning marine activities up to several weeks ahead.
Regional ice charts are produced for:
- the Canadian Arctic (Eastern, Western and Hudson Bay),
- the Great Lakes, and
- the East Coast of Canada.
Regional ice charts are the main climatological product issued by CIS, and are part of the national archives. Data from the charts is also used by the Canadian Meteorological Centre (CMC) in its meteorological models.
5.2.2 Method of production
These charts are meant to show generalized ice conditions; they incorporate all available data, usually within three days of the valid date. The main data sources are RADARSAT and NOAA satellite imagery. The daily ice analysis chart will be referenced; however, using all the detail would make the chart too cluttered, so small areas may be merged.
Defining Polygons
Mandatory boundaries are drawn:
Discretionary boundaries may be used for:
- Concentration
If there is any first-year ice or thicker in an area of 7 tenths or more total concentration (ignoring new ice), may separate areas of first-year ice or thicker that vary by 3 tenths or more.
- Stage of development
- Second-year 8· and multi-year 9· will be used from October 1 to December 31; however, these ice types may be carried throughout the winter when established, especially for consolidated ice in the high Arctic.
- Brash may be used.
- Sd is generally not used except:
- during freeze-up when a trace of new ice is present;
- when remaining ice type concentration is 1/10 or more.
- So used only when the trace of ice is significant (usually first-year or thicker).
- Only small areas of fast ice should be shaded. As the ice area grows, the shading should be replaced with an egg to show ice thickness and stage of development.
- New ice of various concentrations may be grouped together.
- Form of ice:
- Normally each ice type will have only one predominate floe size; however, more than one floe size may be used if the ice is significant (first-year ice or thicker). For example, a few giant floes in a field of medium floes.
- When significant ice types are present within fast ice it is important to maintain their floe sizes, report floe size for the significant ice (usually old ice) and younger forms of ice as code 8.
- When overall concentration of ice in a polygon is 1 to 6 tenths and ice is not evenly distributed, the strip symbol may be used in the form of ice area.
5.2.3 Dissemination of Charts
Regional ice charts are disseminated electronically via a product delivery system. Clients can receive charts via e-mail or though the Internet.
5.2.4 Symbols Used on Regional Ice Charts
Symbols for Defining Limits
| Analysed edge or boundary |  |
| Bergy water boundary |  |
Other Symbols Used
| Bergy water |  | Symbol used to indicate bergy
water conditions. |
| Ice-free |  | Symbol used to indicate ice-free
conditions. |
| Ice island or Ice island fragment |  | Symbol used to indicate
ice island or fragments |
| Open water |
 |
Stipple pattern used to indicate open water areas (less than 1/10).
|
| Fast ice |
 |
Blackened area representing fast ice. |
Note:
Strips and patches (
) will not be used outside of the eggs.
