Comparison of Modeled and SMOS-Observed Surface Soil Moisture Estimates in Preparation for the SMAP L4_SM Assimilation Product

Last year, the European Soil Moisture and Ocean Salinity (SMOS) mission was launched, and in a few years, the United States Soil Moisture Active & Passive (SMAP) mission is scheduled for launch. Both missions will provide surface soil moisture estimates (representing the top 5 cm of the soil column) with a relatively high accuracy and at a relatively fine resolution through previously unavailable low-frequency microwave observations. An initial comparison of SMOS observed brightness temperatures and soil moisture estimates with land surface model estimates and in situ observations is presented over the U.S.. We also describe the procedure for assimilating the SMOS/SMAP observations for the generation of the planned SMAP Level 4 Surface and Root-zone Soil Moisture (L4_SM) product.