STUDY ON THE ESTIMATION OF MICROWAVE LAND SURFACE EMISSIVITY OVER EAST ASIA

Abstract

Estimation of the land surface emissivity is crucial to evaluate the boundary conditions of atmospheric modeling data assimilation. Brightness temperatures observed by satellite passive microwave radiometer give information on emission forma raindrops and scattering by frozen particles. By applying radiative transfer model of the atmosphere, we can estimate the atmospheric hydrological process (i. e., rainfall, snowfall, water vapor, cloud water, etc.). However it is difficult to estimate microwave land surface emissivity at higher frequencies over land. Because land use, land cover and surface wetness over land are various and heterogeneous by comparing with over ocean. Therefore, we aim to estimate the microwave land surface emissivity over East Asia by using observed data and numerical models. Firstly, we investigate the characteristics of land surface emissivity derived from SSM/I, AMSR-E and AMSR2 over Asia and the relationship between land surface emissivity and land hydrological variables based on satellite data sets and numerical models. Secondary, we estimate the land surface emissivity by applying the Community Microwave Emission Model (CMEM) and Community Radiative Transfer Model (CRTM).Simulation results shows the estimated LSE is overestimated and its variability is large by comparing the observed data.