Retrieval of surface and atmospheric parameters over land from SSM/I: Potential and limitations

The potential to retrieve surface temperature, water vapour content and cloud liquid water path from the Special Sensor Microwave/Imager (SSM/I) observations over land is examined, using a variational inversion scheme. The method relies upon prior estimates of the monthly mean land surface microwave emissivities and exploits a priori information on the atmospheric situation (International Satellite Cloud Climatology Project (ISCCP) data and National Center for Environmental Prediction analysis). The accuracy of the surface temperature retrieval is of the order of 1 K, does not strongly depend on surface type and is not very sensitive to the presence of thin clouds. The sensitivity to the water vapour is very low except in the most arid areas. With an accuracy of similar to 0.1 kg m(-2), the SSM/I retrieval does not properly characterize thin clouds, but the major cloud structures are well delineated and qualitative agreement is observed between the SSM/I and ISCCP estimations. This inversion process also has some ability to detect rain events.