Ice chart descriptions

Ice and iceberg charts serve tactical (day-to-day) or strategic (longer-term) planning and operational purposes. They illustrate ice or iceberg conditions at a particular moment in time. The ice information is presented using a standard international code, known as the Egg Code.

The following charts are available from the Canadian Ice Service:

• Daily ice charts
• Regional ice charts
• Departure from normal concentration charts
• Image analysis charts
• Aircraft ice charts
• Iceberg charts
• St. Lawrence River observed ice charts

To view the latest charts, click on the “Latest” links in the tables below, or use our "Product Search" application.

Daily ice charts

Daily Ice charts represent the best estimate of ice conditions at the valid time of the chart, based on an integration of data from a variety of sources, such as satellite,  and ship and aircraft-based visual observations.

The charts describe ice concentration in tenths, ice types or stage of development and the form of ice. The boundary lines for different ice conditions, of particular importance to navigation, are determined by standards.

Ice information is presented in the Egg Code format and colour-coded using the World Meteorological Organization Standard.

In the south, charts are available once ice forms. Charts for Northern Canadian Waters are prepared for areas with known marine activity. Mariners in the Arctic or Hudson Bay are requested to ensure that NORDREG is aware of their location and their plans so that ice information charts will be available.  In those areas, 5 days’ notice may be required in order to initiate a chart for an area. Charts for areas outside of Canada are only produced for specific clients.

Regional ice charts

Regional ice charts show the analysis of ice conditions for a given region valid on Mondays. They are based on an analysis and integration of data from: satellite imagery, weather and oceanographic information, visual observations from ship and aircraft. Satellite imagery is collected over a few days in order to have complete coverage of the area.

The charts indicate the concentration in tenths, stage of development and form of ice. They also list the mean and normal temperatures of some of the region's stations, which give an indication of one of the factors contributing to current ice conditions. Ice information is presented in the Egg Code format and colour-coded using the World Meteorological Organization Standard.

The analysis of ice conditions provided by these charts is useful for the strategic planning of marine operations by shipping companies and other marine interests. These charts are also valuable to researchers studying ice conditions over time.

The frequency of the charts has increased over time. Originally the Arctic Regional charts were issued monthly over winter. Beginning in March 2006, for the International Polar Year, that frequency was increased to twice a month. Since the fall of 2011, the Arctic charts have been issued weekly year-round.

Departure from normal concentration charts

This product shows the differences of concentration between the ice concentration on the current regional ice chart and the Median of Ice Concentration for the period of 1981-2010 as shown in our climatic ice atlases.

Areas in red indicate less ice than normal, and areas in blue indicate more ice than normal. Different shades of red and blue correspond to different categories of the departure from normal ice concentration as shown in the chart legend. Areas with normal concentrations are shown in white. This allows for a quick comparison between current conditions and normal conditions.

This is a product derived from the regional chart and is available up to two hours later. Although the regional Arctic charts are now issued weekly year-round, there needs to be 30 years of data to calculate the normal conditions; therefore, the departure from normal charts are not available each week over winter.

Image analysis charts

The Canadian Ice Service acquires Synthetic Aperture Radar Satellite imagery in order to have data available for the provision of ice information. Upon request of specific clients, Synthetic Aperture Radar imagery will be analysed in more detail than for the daily ice charts and these image analysis usually available to the public.  The area covered by the image analysis coincides with an area related to the satellite path. The path of the satellite changes each day so the chart area shifts from one day to the next. The usual width of the satellite data collection for ice information is about 500 kilometres. At the Canadian Ice Service, we use 100 metre resolution.

When analysing the satellite imagery, the analyst takes into consideration other data such as optical satellite imagery and visual observations from ship and aircraft. The analysis of these images is particularly challenging in conditions such as when seas are rough or if water is on the ice either from melt or rainfall.

Ice conditions are described using the International Standard Ice Code. The code describes the ice in terms of total and partial concentrations, the stages of development and form of the four main ice types present.

[More information]

Aircraft ice charts

These charts present information on ice conditions at the time of the aircraft survey, based on data collected through visual observations. These visual observations are done by Ice Service Specialists with the use of a "Side-Looking-Airborne-Radar" onboard the aircraft. The charts are available year-round but coverage varies depending on the season.

Using the Egg Code format, the chart provides details on the concentration and boundaries of the ice, types and stage of development, floe sizes, leads and fractures, surface topography (ridging and rafting), snow cover, and icebergs where present. The area of coverage is restricted to the flight path of the aircraft and helicopters. With good visibility, visual observations are highly accurate, with a resolution of one to two metres (the size of brash ice).

Aircraft ice charts are regularly used for ship routing by the Canadian Coast Guard, and by companies and other organizations that need detailed information on ice conditions for operational or research purposes.

Iceberg charts

This chart presents an estimate of iceberg conditions in East Coast waters south of 60° N. The conditions are based on visual observations of icebergs from ships, aircraft and occasionally from icebergs analyzed from satellite imagery. The position and size of the icebergs are input into customized software that forecasts the position of the icebergs to 00:00 UTC. An estimated iceberg limit is provided for guidance north of 53 ºN. These areas are not monitored for icebergs using aircraft so the limit is based on climatology and ship reports.

The iceberg analysis chart includes an estimate of the number of icebergs per degree square of latitude and longitude including bergy bits or growlers, the iceberg limit and the sea-ice limit.

This chart is important for those who require iceberg information in East Coast waters, such as ship operators planning routes in the Atlantic.

For additional iceberg information please visit International Ice Patrol.

For more information about icebergs around Greenland contact the Danish Meteorological Institute (DMI).

St. Lawrence River observed ice charts

These charts provide information on ice conditions in the region at the time of the survey, based on data collected through visual observations by Ice Service Specialists onboard Canadian Coast Guard ships and helicopters.

Using the Egg Code format, the chart provides details on the concentration and boundaries of the ice, types and stage of development, floe sizes, leads and fractures, surface topography (ridging and rafting), and snow cover where present. The area of coverage is restricted to the flight path of the helicopters. With good visibility, visual observations have a resolution of one to two metres (the size of brash ice).

For additional information please visit The Canadian Coast Guard’s MarInfo.