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United States Department of Agriculture

Agricultural Research Service

Title: Verification of Patch and Regional Scale Energy Balance Estimates Derived from Microwave and Optical Remote Sensing During Sgp97

Authors
item Kustas, William
item Jackson, Thomas
item Macpherson, J - NAT'L RES COUNCIL CANADA
item French, Andrew

Submitted to: Journal of Hydrometeorology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 7, 2001
Publication Date: N/A

Interpretive Summary: The Southern Great Plains Hydrology Experiment (SGP97) was designed and conducted to extend surface soil moisture retrieval algorithms based on passive microwave observations to coarser resolutions, larger regions with more diverse conditions, and longer time periods. This soil moisture product together with land use and fractional vegetation cover information is used in a remote sensing model for computing spatially distributed evapotranspiration over the SGP97 domain. Validation of the model predictions using tower-based measurements and at regional-scale using aircraft observations indicate average differences of 15-20%, which is within the accuracy of the measurements. The spatially distributed evapotranspiration and model simulated surface temperature maps over the SGP97 region are shown to have great potential for land-atmosphere research. Future research with these results will further our understanding gof large scale soil moisture dynamics and the interaction of soil moisture variability with the atmosphere. Ultimately, when soil moisture observations become routinely available from satellite observations, output from this model will improve the predictive capability of coupled hydrologic-meteorological models leading to better predictions of local and regional climate.

Technical Abstract: The Southern Great Plains Hydrology Experiment (SGP97) was designed and conducted to extend surface soil moisture retrieval algorithms based on passive microwave observations to coarser resolutions, larger regions with more diverse conditions, and longer time periods. The L-band Electronically Scanned Thinned Array Radiometer (ESTAR) was used for daily mapping of surface soil moisture over an area ~40 x 260 km for a 1 month period. Results showed that the soil moisture retrieval algorithm performed the same as in previous investigations, demonstrating consistency of both the retrieval and the instrument. This soil moisture product at 800 m pixel resolution together with land use and fractional vegetation cover information is used in a remote sensing model for computing spatially distributed fluxes over the SGP97 domain. Validation of the model predictions is performed at the patch-scale using tower-based measurements and at regional-scale using aircraft flux observations. Comparisons at the patch-scale yielded discrepancies between model and tower-based sensible and latent heat fluxes of 40% and 20%, respectively. At regional-scales, differences between model and aircraft-based sensible and latent heat fluxes were less, namely on the order of 30% and 15%, respectively. A preliminary comparison of regional average energy fluxes with a model using remotely sensed temperatures was conducted and yielded good agreement. The utility of spatially distributed energy flux and model simulated surface temperature maps over the SGP97 region is discussed.

Last Modified: 4/23/2014
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