Consistency analysis among microwave land surface emissivity products to improve GPROF precipitation estimations

Abstract

To understand the atmospheric phenomena such as rain rate, cloud liquid water, and total precipitable water from satellite microwave observations, the surface contribution should be accounted and be removed from the microwave signal. The objective of this proposed research is to develop a land surface emissivity that facilitates providing this information. The emissivity product will improve the Goddard PROFiling algorithm (GPROF) precipitation estimates. It makes use of microwave measurements from newly launched Global Precipitation Mission (GPM) Microwave Imager (GMI) sensor to produce an emissivity database for a range of frequencies from 6.9 GHz (C band) to high frequencies such as 183 GHz. The goal of this work is to inter-compare four global land surface emissivity products over various land-cover conditions to assess their consistency. The intercompared retrieved land emissivity products were generated over five-year period (2003–2007) using observations from the Advanced Microwave Scanning Radiometer — Earth Observing System (AMSR-E), Special Sensor Microwave Imager (SSM/I), The Tropical Rainfall Measuring Mission (TRMM) Microwave Imager (TMI) and Windsat. First, all products were reprocessed in the same projection and spatial resolution as they were generated from sensors with various configurations. Then, the mean value and standard deviations of monthly emissivity values were calculated for each product to assess the spatial distribution of the consistencies/inconsistencies among the products across the globe. The emissivity products were also compared to soil moisture estimates and satellite-based vegetation index to assess their sensitivities to the changes in land surface conditions.