Large-scale statistical study of Scanning Multichannel Microwave Radiometer (SMMR) data over Antarctica

SMMR data over Antarctica have been statistically analysed for four different periods of 1 year (1981) and compared to geophysical data such as surface temperature, snow-accumulation rate and topography. The spatial variations of the microwave signature are stable with time. Although the ten channels are highly correlated, principal-component analysis reveals the importance of polarization and frequency. The difference between brightness temperatures at the two polarizations is found to be dependent on the atmospheric water-vapour fluxes over the ice sheet, which modify the temperature-accumulation ratio and therefore the snow stratification. The brightness-temperature gradient with frequency is related to the topography of the central plateau area. A more important subsidence over diverging areas could explain the different structure of the accumulated snow.