The Radiation Behavior Analysis of Thin Snow Cover based on Field Measurements by a Multi-Frequency Microwave Radiometer

In this paper, we mainly studied of microwave emission behavior of shallow snow cover with the field experiments over Huabei Plain, China., The evaluation of microwave emission character over snow surface was using the data collected by a ground-based multi-frequency and dualpolarization microwave radiometer (RPG-8CH-DP) at 10.7 GHz, 18.7GHz and 36.5 GHz, with the incidence angles ranging from 20deg to 60deg. Through analysis of the observation brightness temperature, we found that the radiation behavior of thin snow cover is very different from that of deep snow, especially during melting and refreezing period of thin snow cover. One is that the emission over shallow snow surface increased as frequencies increase. Secondly, at the same frequency, when shallow snow was melt in diurnal refreezing-thaw cycle, the emission would decrease. These two emission behavior were caused by the attenuation of snow cover was weak than the increment of emission from the underground snow surface. From this study, it has been shown that the ground-based microwave radiometry provides a useful tool to investigate the radiation characteristics of thin snow cover and snow type identification. It also helps to evaluate snow emission models and develop retrieval algorithms of snow characteristics from space-borne microwave radiometer data.