A simple parameterisation for retrieving soil moisture from passive microwave data

MICRO-SWEAT, a physically based soil water and energy balance model coupled with a microwave emission model, was used to investigate the relationship between near surface soil moisture (theta (0-5)) and L-band microwave brigh tness temperature (T-B) under a wide range of conditions. The effects of so il texture, look angle and vegetation on this relationship were parameteris ed and combined into a simple summary model relating theta (0-5) to T-B. Th is model retains much of the physical basis of MICRO-SWEAT but can be used in more data limiting circumstances. It was tested using a variety of truck -based L-band data sets collected between 1980 and 1982. This paper emphasi ses the need to have an accurate estimate of the vegetation optical depth ( a parameter that describes the degree of influence of the vegetation on the microwave emission from the soil surface) in order to retrieve correctly t he soil water content.