Progress in the development of practical remote detection of icing conditions

NASA has an on-going activity to develop remote sensing technologies for the detection and measurement of icing conditions aloft. As part of that effort NASA has teamed with NCAR to develop software that fuses data from multiple instruments into a single detected icing condition product. The multiple instrument approach, which is the current emphasis of this activity, utilizes an X-band vertical staring radar, a microwave radiometer that measures twelve frequencies between 22 and 59 GHz, and a lidar ceilometer. The radar data determine cloud boundaries, the radiometer determines the sub-freezing temperature heights and total liquid water content, and the ceilometer refines the lower cloud boundary. Data is post-processed with a LabVIEW program with a resultant supercooled LWC profile and aircraft hazard identification.

Ground-based remotely sensed measurements and in-situ measurements from Convair and Twin Otter research aircraft were gathered during the international 2003-2004 Alliance Icing Research Study (AIRS II). Comparisons between the remote sensing system's fused icing product and the aircraft measurements are reviewed here. While there are areas where improvement can be made, the cases examined indicate that the fused sensor remote sensing technique appears to be a valid approach.