The remoteness of the Polar Regions limits the amount of direct observation of sea ice. Hence, more than 95% of the data used in sea ice analyses are derived from the remote sensors on polar-orbiting satellites. Sea ice analyses and forecasts are primarily prepared using satellite imagery and ice reconnaissance.

NIC provides worldwide operational sea ice analyses and forecasts. NIC produces these analyses and forecasts of Arctic, Antarctic, Great Lakes, and Chesapeake Bay ice conditions to support customers with global, regional, and tactical scale interests.

To be classified as an iceberg, the ice must originate from glaciers or shelf ice. The height must be greater than 5 meters above sea-level, the thickness must be 30-50 meters, and the area must cover at least 500 square meters. There are smaller pieces of ice known as bergy bits and growlers. Bergy bits and growlers can originate from glaciers or shelf ice, and may also be the result of a large iceberg that has broken up. A bergy bit is classified as a medium to large fragment of ice. Its height is generally greater than 1 meter but less than 5 meters above sea-level and its area is normally about 100-300 square meters. Growlers are smaller fragments of ice and are roughly the size of a truck or grand piano. They are often transparent but can appear green or black in color. They extend less than 1 meter above the sea surface and occupy an area of about 20 square meters.