Arctic Cloudiness. Comparison of ISCCP-C2 and Nimbus-7 Satellite-derived Cloud Products with a Surface-based Cloud Climatology

Abstract

One surface-based and two satellite arctic cloud climatologies are compared in terms of the annual cycle and spatial patterns of total monthly cloud amounts. Additionally, amounts and spatial patterns of low, middle, and high cloud type are compared. The surface-based dataset is for the years 1951?81, while the satellite-based data are for 1979?85 and 1983?86. The satellite cloud amounts are generally 5%?35% less than the surface observations over the entire Arctic. However, regional differences may be as high as 45%. During July the surface-based cloud amounts for the central Arctic are about 40% greater than the satellite-based, but only 10% greater in the Norwegian Sea area. Surprisingly, (ISCCP) cloud climatology and surface observations agree better during winter than during summer. Possible reasons for these differences are discussed, though it is not possible to determine which cloud climatology is the ?correct? one.