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Using optical-microwave synergy for estimating surface energy fluxes over semi-arid rangelandFirst results of the Walnut Gulch '92 (Arizona, U.S.) experiment concerning the combined use of radar backscattering (ERS-1) and thermal infrared (LANDSAT TM (Thematic Mapper)) data to estimate surface sensible heat flux are reported. The first step investigates the potential use of ERS-1 SAR (Synthetic Aperture Radar) images for surface soil moisture monitoring of the watershed using five calibrated images acquired during the year 1992 (dry to wet conditions). Results show that despite the typical low level of biomass of semi arid rangeland, an attenuation of the soil backscatter (up to 2 dB) can occur during the rainy season mainly due to the vegetation characteristics. A statistical relationship is then used to retrieve the volumetric surface soil moisture from ERS-1 backscattering (sensitivity of 0.23 dB/% moisture) with a resulting root mean square error of 1.3% of soil moisture. In a second step a semi empirical approach based on energy balance relates soil temperatures to this estimated surface soil moisture. Vegetation temperature is then deduced from soil temperatures and LANDSAT TM composite temperature in order to estimate sensible heat flux according to a two layer type model providing an RMSE of 29 W/sq m.
Document ID
19950010708
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Troufleau, D.
(Centre Machinisme Agricole Genie Rural Eaux Forets Montpellier, France)
Vidal, A.
(Centre Machinisme Agricole Genie Rural Eaux Forets Montpellier, France)
Beaudoin, A.
(Centre Machinisme Agricole Genie Rural Eaux Forets Montpellier, France)
Moran, M. S.
(Agricultural Research Service Phoenix, AZ., United States)
Weltz, M. A.
(Department of Agriculture Tucson, AZ., United States)
Goodrich, D. C.
(Department of Agriculture Tucson, AZ., United States)
Washburn, J.
(Arizona Univ. Tucson, AZ., United States)
Rahman, A. F.
(Arizona Univ. Tucson, AZ., United States)
Date Acquired
August 16, 2013
Publication Date
January 1, 1994
Publication Information
Publication: CNES, Proceedings of 6th International Symposium on Physical Measurements and Signatures in Remote Sensing
Subject Category
Earth Resources And Remote Sensing
Accession Number
95N17123
Funding Number(s)
CONTRACT_GRANT: NAGW-2425
PROJECT: NASA PROJ. IDP-88-086
OTHER: NSF BSC-89-20851
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.
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