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Microwave Radiometric Signatures of Different Surface Types in DesertsIn arid environments, specific microwave signatures have been observed with the Special Sensor Microwave/Imager (SSM/I). For a given diurnal change in surface skin temperature, the corresponding change in the microwave brightness temperature is smaller than expected. With the help of a 1D, time-dependent heat conduction model, this behavior is explained by microwave radiation coming from different depths in the soil, depending on the soil type and on the microwave radiation frequency. Using the eight-times daily estimates of the surface skin temperature by the International Satellite Cloud Climatology Project (ISCCP) and a simple Fresnel model, collocated month-long time series of the SSM/I brightness temperatures and the surface skin temperatures give a consistent estimate of the effective microwave emissivity and penetration depth parameters. Results are presented and analyzed for the Sahara and the Arabian Peninsula, for July and November 1992. The case of the Australian desert is also briefly mentioned. Assuming a reasonable thermal diffusivity for the soil in desert areas, the microwave radiation is estimated to come from soil layers down to depths of at least five wavelengths in some locations. Regions where the microwave radiation comes from deeper soil layers also have large microwave emissivity polarization differences and large visible reflectances, suggesting that these areas correspond to sand dune fields.
Document ID
19990056207
Acquisition Source
Goddard Space Flight Center
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Prigent, Catherine
(Columbia Univ., New York United States)
Rossow, William B.
(NASA Goddard Inst. for Space Studies New York, NY United States)
Matthews, Elaine
(Columbia Univ., New York)
Marticorena, Beatrice
(Lab. Interuniversitaire des Systemes Atmospheriques Creteil France)
Date Acquired
August 19, 2013
Publication Date
May 27, 1999
Publication Information
Publication: Journal of Geophysical Research
Volume: 104,
Issue: D10
ISSN: 0148-0227
Subject Category
Earth Resources And Remote Sensing
Distribution Limits
Public
Copyright
Other

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