Late Summer Sea Ice Conditions

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Abstract

Typical sea ice types are shown here at the end of the summer melt season, as well as how often sea ice has been present at any location on September 10 over the last 30 years . Based on the observations of sea ice extent and types over the last 30 years, this map shows how frequently sea ice has been present and what is the most likely predominant ice type and where. Sea ice is any form of ice that is found at sea and has originated from the freezing of seawater. The ice type gives an indication of the thickness of sea ice such as new ice, grey ice, grey-white ice, first year ice, and old ice. Ice represents a danger for navigation. Information on sea ice is essential in estimating transportation costs, and what type of vessel is appropriate.

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This map shows the typical sea ice types at the end of the summer melt season (September 10) as well as frequency of sea ice on that date. The frequency of sea ice indicates how often sea ice has been present on September 10 over the last 30 years.

The ice type gives an indication of the thickness of sea ice. When sea ice first forms it is referred to as new ice. As winter progresses it grows in extent and thickness. As sea ice thickens it is referred to successively as grey ice, grey–white ice and first year ice. During the summer sea ice melts and any first year ice remaining at the end of the summer melt is then renamed "old ice" on October 1.

Various ice types can be present in a given area, but one of them will be predominant. The predominant ice type is the one with the greatest concentration in a particular area. However, because of the danger that old ice represents for navigation, and if 40% or more of the area contains old ice then the predominant ice type will be old ice even if thinner ice in greater concentration is present.

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Norwegian Bay (Nunavut) early October from 30 feet showing second year ice (old ice) and frozen puddles.

Map Description

This map shows the frequency of sea ice and the most likely predominant ice type encountered at the end of the summer melt season (September 10). At the end of summer melt, all the sea ice in southern latitudes will have melted and sea ice will remain only in northern Canadian waters. Moreover, since the thinner types of ice melt first, only the thicker types, such as old ice and first year ice, will remain.

There are extended areas of old ice in most Canadian Arctic waters including Beaufort Sea and Baffin Bay. It should be noted however that in most of these areas the frequency of the presence of sea ice is mostly less than 25% and concentrations (being the proportion of water surface covered by ice) are low. Typically, the presence of old ice at the end of the summer melt is limited to areas between the Arctic islands and in the Arctic Ocean (as shown by frequencies greater than 50%) but still presents a danger for navigation.

Also shown are areas of permanent ice and the estimated maximum extent of ice observed outside Canadian waters. Areas designated permanent ice indicate where ice has been observed all year round throughout the period 1969 to 1998. The estimated maximum extent of ice outside Canadian waters displays where ice has been observed on September 10 at least once over the 30 year period.

Sea Ice Animations

Two animations are created for sea ice. Each animation was presented in two different formats: flash and html. The Atlas of Canada relies on Macromedia’s technology for the delivery of multimedia content. The Atlas of Canada media player will attempt to detect whether you have the necessary software installed, and will give you notice if you do not. In order to play the animations in flash, you must install the Macromedia Flash Player. Installation instructions on Macromedia Flash Player are available at Macromedia Web site.

• Animation of the Minimum Extent of Sea Ice 1969 to 1998 presents the variation of the minimum extent of ice between each year for the period 1969 to 1998, with a concentration of 9/10 or greater. A concentration of 9/10 corresponds to at least 90% of the water which is covered by ice. flash or html
• Animation of the Seasonal Change of Sea Ice presents a normal ice season in Canadian waters by showing the normal evolution of sea ice throughout the course of a year. The animation does not reflect any real observed sea ice season, but rather a 30-year statistical compilation. flash or html