Study of Himalayas Ice using MSMR Data

The study of the extent of ice on Himalayas has been done using data from different passive sensors on board satellites, starting from Nimbus. The Indian satellite OCEANSAT-I carried a microwave passive sensor MSMR operating at different frequencies 6.6, 10.6, 18 and 21 GHz with dual polarization having different spatial resolutions of the order of 150, 75 and 50 km. For study of snow and ice the higher frequency like 37 GHz gives better correlation. Here the study has been done at 18 GHz as 21 GHz frequency is affected by presence of water vapour. The frequency chosen gives the extent of snow/ice in the Himalayan region. The 18 GHz data, over certain location was compared with the data of 6.6 GHz as 6.6 GHz data can penetrate dry snow/ice and so when compared the idea of thickness of snow/ice could be assessed. The brightness temperature measured for vertical polarization is higher as compared to horizontal polarization in both frequencies. This indicates that the surface is smooth. The emissivity for smooth surface gives the variability of brightness temperatures in two different polarizations. Different areas of Himalayas have been chosen for the comparison of brightness temperature at two frequencies they are 6.6 GHz and 18 GHz. It is observed that the temperatures in 18 GHz are different as compared to 6.6 GHz for both V and H polarization. The temperature obtained at 6.6 GHz is not from the surface of ice but from certain depth where the effect of underlying land is observed. The brightness temperature at 18 GHz is mostly from surface which is close to dry ice/snow and so the brightness temperature is lower as compared to that obtained at 6.6 GHz The data for frequency channel 6.6 GHz covers larger grid so frequency channel 10.65 GHz is used for study of snow depth as it provides better results. In this paper the detailed study of Himalayan region at 10.65 GHz and 18 GHz frequencies is presented.