Sea Ice
The Arctic sea ice cover is vast in areal extent covering millions of square kilometers, but is only a thin veneer a few meters thick. This ice cover plays many roles. It is a barrier limiting the exchange of heat, moisture, and momentum between the atmosphere and ocean; a home to a rich marine ecosystem, including human communities; and an indicator of climate change. Sea ice extent has been monitored using passive microwave instruments on satellite platforms since 1979. The months of September and March are of particular interest because they are the months when the Arctic sea ice typically reaches its maximum and minimum extent respectively.