Remote sensing of cirrus cloud parameters eased on a 0.63-3.7 mu m radiance correlation technique applied to AVHRR data

Using the data gathered from the Advanced Very High Resolution Radiometer ( AVHRR) 0.63 and 3.7 mu m channels, an algorithm for the inference of cirrus cloud optical depth and mean effective size has been developed for the fir st time. This scheme is based on the correlation between the 3.7 mu m (tota l) and 0.63 mu m radiances that is constructed from radiative transfer calc ulations involving ice crystal clouds. Application of the algorithm to AVHR R channels has been performed by using data sets that were collected during the First ISCCP Regional Experiment, Phase II, Cirrus Intensive Field Obse rvation (FIRE-II-IFO; November-December 1991) at Coffeyville, Kansas. For v alidation, the in-situ data collected by the balloon-borne replicator and a irborne 2-D probes that were collocated with AVHRR pixels were carefully an alyzed for five cases involving single and multiple cirrus cloud layers. We demonstrate that the retrieved cirrus cloud optical depths and mean effect ive sizes compare reasonably well with those determined from the insitu ana lyses.