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Title: SYLAB L BAND MICROWAVE OBSERVATIONS OF SOIL MOISTURE REVISITED

Author
item Jackson, Thomas
item Hsu, Ann
item VAN DE GRIEND, A - FREE UNIV-AMSTERDAM
item EAGLEMAN, J - UNIV OF KANSAS

Submitted to: International Journal of Remote Sensing
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/5/2003
Publication Date: 7/10/2004
Citation: Jackson, T.J., Hsu, A.Y., Van de Griend, A., Eagleman, J. 2004. Skylab L band microwave observations of soil moisture revisited. International Journal of Remote Sensing. 25:2585-2606.

Interpretive Summary: Data collected by the only very low frequency (L band) passive microwave radiometer to ever fly in space were recovered and reprocessed to conduct soil moisture analysis at test sites in the western hemisphere. The data were collected by an instrument on Skylab in 1973 and 1974. Although much data were collected during these missions it was never archived and all except the data set recovered and reported here was lost, which makes this an extremely rare archive. Data were analyzed using global scale model outputs that were not available at the time of the mission. This resulted in new insights on the ability of L band radiometry to estimate soil moisture in diverse environments. It is anticipated, these estimates of soil moisture will provide a valuable dataset for the hydrologic community. These results will contribute to experiment design and the potential operational implementation of this technique in hydrologic, climate and agricultural applications.

Technical Abstract: In preparing for future L band passive microwave soil moisture satellite missions, investigators have employed ground, aircraft and satellite sensors. Of the satellite sensors, there has been only one instrument that provides any heritage at L band, the Skylab S-194 instrument that operated in the 1970s. Here a data set from the S-194 was located and recovered. Data from these Skylab missions have been analyzed and reported in a few applications, however, these studies utilized limited validation and exploited only a portion of the data collected. In this investigation we explored the use of products from climate model reanalysis projects as ancillary or alternative validation data. Analyses showed that the reanalysis outputs were not accurate and would be of limited value. Tests using a radiative transfer based soil moisture retrieval algorithm matched the observations available for validation. These results support the use of this approach as a tool in understanding a wider range of vegetation condition effects on soil moisture retrieval.