Nephanalysis of the GMS Imagery Data

Abstract

Techniques estimating cloud amount and classifying cloud type from GMS IR and/or VIS imagery data have been developed and evaluated. Cloud amount is estimated by a Two-Threshold-Method (TTM) which takes account of the partially cloud-covered pixels. Cloud type is classified by a discriminant analysis technique. Fairly good agreement is obtained between the satellite estimated and the surface observed cloud amounts. The comparison between the satellite classified and ground observed cloud types shows correctness ratios of 52.9% and 47.7% for the daytime and nighttime respectively, but the distinction between cumulus and middle clouds seems insufficient. The techniques were applied to produce the time series of cloud amounts and types during the period from 3 to 11 Sept. 1980, and the results were acceptable.