On the feasibility of MISR cloud-motion wind retrievals

Abstract

The feasibility of deriving cloud motion vectors from data to be obtained by the Multiangle Imaging SpectroRadiometer (MISR) is demonstrated. It is shown that from a triplet of near-simultaneous multi-angle imagery cloud motion and height can be separated. The expected errors in the calculated cloud top height and cloud velocity are approximately 300 m and 3 rn/s, respectively, with the cross-track velocities being more accurate than the along-track ones. The possibility of determining the speeds of individual layers in a 2-layer configuration is also illustrated. The necessary conditions for separating cloud height and motion and the optimal choice of wind retrieval cameras are discussed. A 3-D ray intersection algorithm is derived to simultaneously compute cloud top height and speed. The algorithm is tested on simulated clear-sky and cloudy datasets. Possible applications of MISR winds include studies of large-scale average wind patterns or synoptic-scale phenomenon, and numerical weather prediction.