Using Hyperspectral Sounders to Detect Cold Air Aloft over Alaska

Air temperatures -60C and colder at cruising elevations used by jet aircraft can be hazardous to aviation, as jet fuel will gel at these temperatures, and outbreaks of such “cold air aloft” can occur over the Arctic Ocean and Alaska. The National Weather Service's Center Weather Service Unit (CWSU) in Anchorage, Alaska provides weather support to air traffic controllers directing traffic over the Arctic Ocean and Alaska. While numerical weather prediction models help meteorologists forecast the occurrence and movement of cold air aloft, to date there has been no observational dataset revealing the actual presence of cold air aloft in real time in regions not sampled by conventional radiosondes. Hyperspectral sounders, such as the Cross-track Infrared Sounder (CrIS) aboard the Suomi NPP satellite, are well-suited for observing cold air aloft over Alaska and the Arctic Ocean due to the sensitivity of these instruments and the comparatively high number of passes satellites in polar orbits make per day over the high latitudes. The Geographical Information Network of Alaska receives CrIS data from the SNPP satellite via direct broadcast, uses the Community Satellite Processing Package to generate products from the data, and then delivers the products to the National Weather Service in Alaska, all with the goal of providing meteorologists a vital observational dataset while minimizing latency.