Towards Aiding Aviation Safety: Detection of Cold Air Aloft Using COSMIC RO and AIRS Hyperspectral IR Sounder

In the Arctic region, cold air aloft can pose serious threats to aviation safety. When such pockets of cold air or protrusions of the stratospheric polar vortex are located at jet aircraft cruising altitudes, jet fuel can gelify with temperatures under -65 degrees Celsius. Meteorologists of the National Weather Service in Anchorage, Alaska are able to use forecast models to predict these cold air events, but no real time observations aside from sparse radiosonde coverage is available. Work is ongoing at CIMSS in Madison, Wisconsin to investigate the utility of real-time hyperspectral infrared sounder retrievals in detecting these events for use in the Alaskan National Weather Service office as part of the JPSS risk reduction and proving ground activities.

The focus of this paper is to use radio occultation (RO) and available radiosonde data together to characterize the frequency as well as vertical and horizontal extent of cold air aloft events. The high vertical resolution of RO and its quality of being most accurate in the upper troposphere and lower stratosphere make it a good candidate for detecting the cold air's vertical extent. Focus is set on regions over the Arctic and Alaska over a 7 year time period. COSMIC dry and wet temperature products from UCAR are analyzed. Similar analyses are also made for NASA's AIRS version 6 temperature products. Comparisons of the AIRS and COSMIC analyses help highlight each of the instrumentations strengths in this application. This work will provide insight on how RO and hyperspectral infrared sounder retrievals can be used in real-time applications to make use of the direct broadcast capability on Suomi-NPP and JPSS and the product applications available through the Community Satellite Processing Package (CSPP) project.