The sea ice/sea surface temperature desk at the Anchorage, Alaska Weather Forecast Office (WFO) provides sea ice analyses, and sea ice forecasts for the Beaufort Sea west of 125W, the Chukchi Sea east of 175E, the Bering Sea east of 171E and Cook Inlet. The most effective tool the forecaster has for analyzing sea ice is Synthetic Aperture Radar Satellite (SARSat) imagery. SARSat is an active microwave instrument (radar frequency) whose data consists of high-resolution (10M) reflected returns from the Earth’s surface, based on a polar orbiting satellite.

Unlike the more common imager channels used by meteorologists (e.g., visible, infrared, and water vapor) SARSat passes through the atmosphere relatively unaffected by clouds, precipitation or sun-angle to scan surface features. The energy returned to the satellite is a function of the physical characteristics of the surface features. This attribute makes SARSat ideal for analyzing sea surface features over the stormy northern latitudes.

However, there are a limited number SARSat passes on any given day. Imagery from the more abundant SSM/I and QuikSCAT imagers are used to fill in the data gaps. Though coarser in resolution and more limited in capability, imagery from these satellites provide consistent, daily background information of sea ice for the entire ocean basin.

What makes these tools vitally important to the mission of the NWS in Alaska is that the imagery is used daily to improve ice analysis and forecasts for the most dangerous industry/occupation in the United States: the crab fishery in the Bering Sea. Prior to1995 the average yearly death/vessel loss rate for the preceding ten years was 5 men dead/2 vessels lost per crabbing season. During the crabbing seasons of 1998 through 2003, 5 of the 6 years the industry experienced no loss of life or vessels. Feedback from customers indicate that at least a small portion of the success is attributable to information derived from SARSat, and SSM/I and QuikSCAT.