Analysis and simulation of Nam Co Lake on brightness temperature of passive microwave by satellite data

The Tibetan Plateau is the highest plateau. And snow in covered at Tibetan Plateau can exert have important influence on the study of climate change and hydrological cycle. In this paper, we found that the brightness temperature of horizontal polarization at Nam Cu Lake is very low, which is about 170K at 18.7 GHz, by the analysis of the time series of the brightness temperature observed by AMSR-E. Even if the lake got frozen, the brightness temperature of horizontal polarization of ice is about 220K at 18.7 GHz, which is much lower than that at land. Then we use HUT (Helsinki University of Technology) snow emission model for a homogeneous snowpack - ice - water system to simulate the brightness temperature at AMSR-E´s frequencies which are used in the current algorithms of estimation SWE at the satellite scale. Also from the seasonal variation of the time series of the brightness temperature, we could see that the brightness temperature of lakes increased sharply when being frozen and decreased rapidly when being melting. The HUT model can match well with the observed brightness temperature at 18.7GHz at horizontal channel.