Global 3D-Nephanalysis of Total Cloud Amount: Climatology for 1979

Abstract

A one-year global total cloud amount climatology has been compiled from the U.S. Air Force's three-dimensional nephanalysis cloud archive. The derived cloud distributions are shown to be reliable and in good agreement with known features of the general circulation and with other widely used cloud climatologies. Climate studies often require additional information to complement the mean monthly statistics. Considerable attention has been devoted here to the interpretation of the monthly temporal variability statistics. The combination within the U.S. Air Force cloud archive of traditional surface cloud observations and high resolution satellite information hinders a direct interpretation of the variability statistics. Information about the percentage of ?okta? (i.e. surface) observations and the percentage of binary (usually satellite) observations, which characterize the monthly cloud distribution, is required to permit interpretation of the cloud amount monthly mean and variability statistics. The processed monthly mean data, on a spatial grid with a resolution of approximately 46 km, are available on computer compatible magnetic tape. Their primary disadvantage is that they represent only the year 1979, while their advantage is their high spatial resolution.