Comparison of Mean Cloud Cover Obtained By Satellite Photographs and Ground-Based Observations Over Europe and the Atlantic

Abstract

An important field of weather observation is the statement of cloud cover of the sky. Clouds not only are significant for the daily weather forecast but also are important for energetic calculations of atmospheric processes. A milestone in monitoring of large-scale cloudiness is the application of weather satellites. With the daily pictures from ESSA 8, estimations of the cloud cover in tenths for geographical 2.5° sections have been made for a period of 3 yr (Dec. 1, 1967–Nov. 30, 1970), and the mean seasonal cloud distribution over Europe and the Atlantic has been calculated. Twenty-nine synoptic stations have been used for comparison between satellite and surface observations. A detailed discussion shows the reasons for the higher surface values of cloud cover compared to the satellite values. The mean annual differences, with values about 0.9 tenth over northern Europe and 1.5 tenths over southern Europe, are caused by geometric, synoptic, and orographic factors, there is a basic difference of about 0.6 tenth between the two different observation methods.