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Funded by the National Ocean Service at the National Oceanic and Atmospheric Administration (NOAA) through AOOS 

Alaska Ocean Observing System (AOOS), the Alaska Center for Climate Assessment and Policy (ACCAP), and the Scenarios Network for Alaska and Arctic Planning (SNAP)

Pack ice where sea ice concentration >9/10 (90%), and floes are tightly packed to frozen together. Very little, if any, seawater is visible.

The permanent ice zone that remains in summer after all melting has occurred.

A stretch of navigable water between pack ice and the shore. Vessel capability determines navigability of sea ice.

Day of the year when the sea ice covers the largest area of the Arctic (or Antarctic).

Any form of ice found at sea that has originated from the freezing of seawater.

Viewing something from a distance. Satellites and other instruments are used to collect a variety of remote sensing data: visible light: 

A wide area of open water in an area of pack ice. A polynya differs from a lead in that leads are long and narrow.