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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)

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

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.

A region that is covered in sea ice year-round. Most of the sea ice in the permanent ice zone is multi-year ice, but younger ice and open water may still be present. The permanent ice zone is what remains in summer after all melting has occurred (also known as the summer minimum extent).

Predominantly circular pieces of sea ice from 30 cm – 3 m in diameter and up to 10 cm thick, with raised rims due to the pieces striking against each other.

Sea ice that not attached to the shoreline and that drifts in response to winds, currents, and other forces. Some prefer the generic term drift ice, and reserve pack ice to mean drift ice that is closely packed.