Airborne Remote Sounding of Cirrus Cloud Parameters Using ARES Channel Data

摘要

Results of the phase function, single scattering albedos, and extinctioncoefficients for three representative cirrus cloud ice crystal size distributions are presented for the Airborne Remote Earth Sensing (ARES) System 2-6.4 microns wavelengths. The ice crystal sizes range from 5 to 800 microns with shapes spanning from bullet rosettes, hollow and solid columns, plates, to aggregates. The computations are carried out on the basis of a unified theory for light scattering by ice crystals recently developed by our research group. Effects of incorporating small ice crystals on the scattering and absorption calculations are assessed. An airborne retrieval algorithm to infer cirrus cloud temperature, optical depth, and mean effective sizes is subsequently presented using the ARES 5.1-5.3 and 3.7 microns channels data. This scheme has been applied to the ARES data collected on September 16, 1995, over the Hanscom AFB area. Validation of the retrieved cloud temperature, optical depth, and mean effective size is carried out using the collocated and coincident ground-based 8.6-mm radar data and in-situ size distributions from the 2D probe on board HARP.