Examination of 'global atmospheric temperature monitoring with satellite microwave measurements' (3) cloud and rain contamination

Abstract

Observations in channel 1 (Ch. 1, 50.3 GHz) and channel 2 (Ch. 2, 53.74 GHz) of the Microwave Sounding Unit (MSU) over the convective areas of tropical oceans are analysed to reveal the nature of extinction (contamination) in these data. From this analysis we find Ch. 2 data are not free from the influence of clouds and rain. Extinction due to clouds and rain manifests primarily as emission in Ch. 1, and as absorption in Ch. 2. Scattering due to hydrometeors in these channels apparently is of secondary importance. Furthermore we show, in the convective areas of tropical oceans, contamination due to hydrometeors in MSU Ch. 2 data is significant and it is extensive in area. Based on this study we conclude Spencer, Christy, and Grody (this issue) underestimate this contamination. © 1996 Kluwer Academic Publishers.