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United States Department of Agriculture

Agricultural Research Service

Title: Influence of Near-Surface Soil Moisture on Regional Scale Heat Fluxes: Model Results Using Microwave Remote Sensing Data from Sgp97

Authors
item Bindlish, Rajat - USDA-ARS
item Kustas, William
item Diak, George - COOP INST FOR SATEL STUDY
item Mecikalski, John - UNIV OF WISCONSIC-MADISON

Submitted to: IEEE Transactions on Geoscience and Remote Sensing
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 15, 2001
Publication Date: August 13, 2001

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 soil moisture were spatially correlated and found to be significant over the experimental domain. However, it is found that these correlations vary with environmental/moisture conditions, but even more significantly depending on the area selected within the SGP97 domain. The results of this study have implications regarding the influence of near-surface soil moisture on atmospheric dynamics and the scale at which these relationships are evaluated. 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. 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. With regional maps of near-surface soil moisture, W, and the heat fluxes, correlations are computed to evaluate the influence of near-surface soil moisture on the turbulent fluxes. It is found that for the whole SGP97 domain, correlations, R, between W and LE range from 0.4 to 0.6 (R = 0.5 on average), while correlations between W and H vary from -0.3 to -0.7 (R = -0.6 on average). It is found that these correlations vary with environmental/moisture conditions, but even more significantly depending on the area selected within the SGP97 domain. The results of this study have implications regarding the influence of near-surface soil moisture on atmospheric dynamics and the scale at which these relationships are evaluated.

Last Modified: 9/22/2014
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