A simple cloud-radiation statistics at Mizuho Station, Antarctica

Cloud distribution characteristics at Mizuho Station, Antarctica are discussed. The transmittance of the direct solar radiation and downward longwave radiation are used as an index of clouds. The frequency of occurrence of the clear sky-1.0 transmittance, minimum extreme of downward longwave radiation-is very high throughout the year, which may be pronounced characteristics at inland stations. The direct solar beam transmittance is a good indicator of clouds in the sunlit season. The downward longwave radiation varies sensitively according to the cloud. The normalized emissivity defined from the longwave flux has a good correlation to the cloud amount, and is a good indicator of clouds throughout the year