Relation between the Observed and Theoretical Brightness Temperature over Indian sub-continent using SSM/I data.

Passive microwave remote sensing has proved to be a valuable tool for monitoring various parameters of Land, Ocean and Snow surfaces. The passive microwave remote sensing data can be utilized for deducing various subsurface and atmospheric parameters. In the present thesis work, efforts have been made to analyse the effect of atmospheric attenuation for various land cover types at all SSM/I frequencies in both polarizations. For better interpretation of results, the Indian sub-continent has been divided as snow covered region, Indo-Gangetic basin, Deccan trap, Thar Desert, Shield area. Separate analysis has been carried out for the Arabian Ocean and the Bay of Bengal. The observed brightness temperature data have been extracted from EASE Earth Grid brightness temperature data sets over the Indian sub-continent and surface temperature data from Global Atmospheric Analysis Data from National Center for Environmental Prediction, Washington DC. The simulated brightness temperature has been calculated by considering the appropriate dielectric properties for a particular land cover type. The difference between the observed and simulated brightness temperature is attributed to the atmospheric attenuation. This atmospheric attenuation factor for various land cover types of Indian sub-continent at all frequencies of SSM/I have been analyzed. The monthly analysis of emissivity and brightness temperature data has been carried out. The Oceanic are as show more attenuation factor compared to land regions. The emissivity images for oceanic regions have been generated for peak summer (July) and winter (January) months for the year 1988. The emissivity pattern changes drastically from January to July. In land areas, Snow regions are more effected by the atmosphere. The results discussed in the present thesis work will be useful in the qualitative and quantitative interpretation of microwave remote sensing data in general and in particular to SSM/I data over Indian sub-continent. The atmospheric attenuation factor can be useful for atmospheric corrections specially for the optical remote sensing data over oceanic region.