Comparison of the passive microwave spectral signature of the Antarctic ice sheet with ground traverse data

Scanning Multichannel Microwave Radiometer (SMMR) data are compared with the snow characteristics measured during several traverses over Antarctica including average density over 0–2 m, 10 m temperature, grain-size distributions and number of strata. First a local study of specified areas and then a global study show some strong dependence between satellite data and ground data. The polarization ratios are affected by the stratification of snow (number and nature of layers); large polarization ratios correspond to strong stratification, mainly for the lower frequencies. Because low density induces strong stratification there is also a dependence between polarization ratios and density even if the density is not the critical factor. The gradient ratios are linked to the grain-sizes as determined from detailed stratigraphies; the larger the grain-size, the smaller is the gradient ratio between 6.6 and 18 GHz.