Retrieval of global microwave surface emissivity over land

Atmospheric microwave remote sensing over land and ice is a great challenge. Traditionally microwave approaches have been severely limited over land, and are only routinely performed over ocean areas. This is due to the higher emissivity values over land and their dynamic behaviors on daily to seasonal timescales. The lack of reliable land surface emissivity knowledge has hindered full exploitation of the capabilities of operational microwave satellite sensors such as AMSU and SSM/I. Microwave emissivity models have been developed to predict the land emissivity and continue to show promise, but independent global measurements of emissivity are needed for model validation and future improvements.

A 1DVAR emissivity retrieval algorithm has been developed which uses AMSU data to retrieve emissivity at frequencies from 23 to 183 GHz. A simultaneous retrieval of the temperature and water vapor profiles as well as cloud liquid water is also performed. Our emissivity results are compared with the NOAA NESDIS Microwave Emissivity Model for a variety of conditions. Applications of the dynamic global emissivity database will also be discussed.