Sea Surface Emission Characteristics as Viewed by the Spin-Scanned Satellite Microwave Radiometer (SAMIR) on Board Bhaskara

Emission characteristics from ocean surfaces around the Indian subcontinent have been studied using data from the satellite microwave radiometer (SAMIR) on board Bhaskara, the first Indian satellite for Earth observations. SAMIR is a three-channel microwave radiometer, with two channels operating at around 19 GHz and one at 22.235 GHz. Each radiometer has a temperature sensitivity of better than 1 K, and the ground resolutions are 150 and 230 km, respectively. The radiometers are primarily intended for studies related to meteorology and oceanography, and for general land-related investigations. One of the special features of the payload is that it can be operated in two different modes of spin of the satellite. In the first (normal mode), the antennas scan along the satellite track, and in the other (alternate mode), the antennas scan across the track. The data of the alternate mode have been compared with theoretical emission models and also with the normal-mode analysis. The results correlate well with the established theoretical studies for both the horizontally and vertically polarized components of microwave emission from the sea surface. The effects of mixed polarization also correlate well with the data.