Development of Global Land Surface Emissivity Map at Amsr-e Passive Microwave Frequencies

Microwave emissivity over ocean is relatively well understood by scientists. However, over land because of the existence of different land covers and their various physical properties land surface emissivity retrieval does not seem to be straightforward. Land emissivity plays a key role in Numerical Weather Prediction (NWP) models, since it acts like a crucial boundary condition. The accuracy of prediction of this parameter will mitigate the impact of cloud liquid water in retrieving air temperature, water vapor, and surface temperature. Land emissivity also can be used as an indicator of soil moisture and land use/land cover variation especially in presence of clouds, since microwave emissions can penetrate clouds. The objective of this study is to develop global land emissivity maps using AMSR-E passive microwave observations at different frequencies along with several ancillary data. database has been used to obtain several inputs for the proposed approach such as land surface temperature and cloud mask. These datasets have 3 hourly temporal resolution and about 30 km spatial resolution. Additional ancillary data such as TOVS water vapor amount and atmospheric temperature profile have been also used to assess the atmospheric contribution. In this study, first, simple experimental equations were used to calculate the atmospheric correction parameters at 19 and 37 GHZ (Choudury 1993), and for 10.7 and 6.9 GHz no atmospheric correction was considered. Although it is well known that the correction of the atmospheric effect is solely required at higher frequencies (over 19 GHz), our results have shown that a correction at 10.7 GHz is also necessary. In order to systematically correct for the atmospheric contribution at different