Soil temperature error propagation in passive microwave retrieval of soil moisture

In the near future two dedicated soil moisture satellites will be launched (SMOS and SMAP), both carrying an L-band radiometer. It is well known that microwave soil moisture retrieval algorithms must account for the physical temperature of the emitting surface. One proposed approach is the use of temperature output from numerical weather prediction (NWP) models. A radiative transfer model, as implemented in the most commonly used soil moisture retrieval algorithms, will be used to assess sensitivity to errors in the estimated surface temperature. It is shown that soil temperature errors will likely limit the vegetation range within which soil moisture can be retrieved with an accuracy of 0.04 m³m^-3. These results should contribute to improved algorithm design and implementation for the new L-band satellite missions.