About Landfast Ice

Landfast ice (also called shore-fast ice) is a type of sea ice that primarily forms off the coasts in shallow water. In Antarctica, fast ice may also extend between grounded ice burgers. Unlike pack ice in deep water, landfast ice attaches itself to the coastlines or shallow sea floor on the continental shelves. As a result, landfast ice does not drift with currents and wind.

Most landfast displays a distinct seasonal cycle. Except in high Arctic (e.g., the Canadian Archipelago), where ice may linger for several years dependent on weather conditions, landfast ice starts to grow in fall and melts away completely in summer. This seasonal feature of the ice has a profound influence on coastal resources and residents. The offshore extension of landfast ice varies, dependent largely on coastal bathymetry and topography. For instance, landfast ice extends only to about 50 m off the coast of the Beaufort Sea due to its narrow shelf, whereas in the Eastern Siberian and Laptev seas, landfast ice can extend up to 200 m off the cost due to the broad shelf there with shallow water.  

The typical thickness of landfast ice is about one to two meters, and its appearance is normally smooth and level in the inner part of the landfast ice pack but can be highly deformed rubbles at its seaward boundary. This strip of rough ice is also called stamukhi zone, which typically occurs between smooth fast ice and drifting pack ice. The stamukhi zone is a distinct feature along the Beaufort coast where the offshore pack ice motion is largely driven by wind and currents, pushing against the immobile landfast ice pack and creating convergence and deformation.