CLOUD DISTRIBUTION IN THE ANTARCTIC FROM AVHRR DATA AND RADIATION MEASUREMENTS AT THE SURFACE

Cloud distributions were analysed from the AVHRR data of the NOAA satellite received at Syowa Station (69-degrees-S, 39-degrees 35'E) in Antarctica. Algorithms to derive cloud amount using the brightness temperature difference of infrared channels 3 and 4, or 4 and 5, were assessed by comparing the satellite cloud amount to the manual cloud amount and the downward longwave radiation at the ground surface. Cloud amounts obtained by the brightness temperature difference of channels 3 and 4 in summer agreed with the manual cloud amounts at the surface, and was highly correlated to the downward longwave fluxes. Cloud amounts from channels 4 and 5 showed a rough agreement with the surface cloud amounts. Distributions of cloud derived from the pilot datasets were examined.