Study of Atmospheric effects on AMSR-E microwave brightness temperature over Tibetan Plateau

This paper demonstrates a study to the atmospheric influence on the passive microwave brightness temperature (BT) in Tibetan Plateau area at clear-sky condition. The absorption and emission of dry air and water vapor are considered as the main contribution of atmosphere at the fact of cloud-free. We choose the day of Dec. 07, 2005 as an example, and calculated the atmosphere absorption factor and effective atmospheric temperature which are based on an updated atmospheric microwave absorption model. With the help of MODIS-Aqua land surface products (MYD11_L2) and MODIS atmospheric profile (MOD07_L2) products, which can decide a real atmospheric status, a simplified radiative transfer equation (RTE) is employed to estimate the AMSR-E frequencies surface emissivity over Tibetan Plateau. As a result, the surface actual microwave brightness temperature is obtained through the product of retrieved emissivity and MODIS LST, it can be found that the atmospheric contribution to the brightness temperature add up to about 5.56 K at 89.0 GHz and average 0.54 K at 23.8 GHz somewhere Tibetan Plateau in the cloud-free winter days, and the space variation of atmospheric effect to microwave BT has been further discussed.