Using Polar-Orbiting Satellites to Monitor the Upper Atmosphere for Cold Air Pockets that are Potentially Dangerous to Passenger Aircraft

During the winter months, especially at high latitudes, temperatures at altitudes used by passenger aircraft can get cold enough to cause jet fuel to freeze. The temperature where the freezing of jet fuel becomes a concern is typically considered to be -65°C. The knowledge of the location of pockets of air this cold is therefore of vital importance to weather forecasters. Radiosonde observations are available and widely used, but the temporal and spatial sampling provided by the network is too coarse to accurately track the cold air pockets. Polar-orbiting satellites can provide vertical temperature profiles with higher temporal and horizontal spatial resolution and thus help to monitor the atmosphere for air which is dangerously cold for aircraft travel.

Three atmospheric profiling systems available from polar-orbiting satellites are discussed: the Microwave Integrated Retrieval System (MIRS), the NOAA Unique CrIS/ATMS Processing system (NUCAPS), and the Dual Regression (DR) technique. These algorithms are compared in their ability to detect regions of cold air aloft, with collocated radiosondes being used as ground truth. In addition to this validation work, CIRA is working toward the development and maintenance of a web-based product, which can provide near real-time monitoring of the regions of cold air aloft.