Centi- and millimeter-wave atmospheric transmittance estimation and analysis over China

Three years radiosoundings measurement at China were inputted in the Salonen-Uppala cloud detection algorithm to distinguish cloud layers, and to estimate cloud liquid water content therein, then atmospheric transmittances of China at frequencies of the Advanced Microwave Scanning Radiometer - Earth Observing System (AMSR-E) were estimated using MPM and Mie theory. The validation expressed a good agreement with the field experimental observations. A comprehensive temporal and spatial analysis has been executed, appeared that microwave atmospheric transmittances were much dependence on water vapor distribution, and transmittances were relatively stable from October to March, but fluctuated obviously in summer. Transmittances of northwest China were higher than those of south China, and the highest transmittances were in Qinghai-Tibet Plateau region. The correlation coefficient between microwave atmospheric transmittance and MODIS total column precipitable water vapor (MYD05) in January at 18.7, 23.7, 36.5 and 89 GHz was 0.904, 0.923, 0.847 and 0.879 respectively. The relationship between monthly averaged microwave atmospheric transmittances and MYD05 could be used to estimate the high resolution microwave atmospheric transmittances products. The results prepared to ensure atmospheric effect in the applications of passive microwave remote sensing.