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United States Department of Agriculture

Agricultural Research Service

Research Project: IRRIGATION MANAGEMENT AND AUTOMATION FOR INCREASED WATER USE EFFICIENCY Title: Daily evapotranspiration estimates by scaling instantaneous latent heat flux derived from a two-source model

Authors
item Colaizzi, Paul
item Kustas, William
item Evett, Steven
item Howell, Terry
item Gowda, Prasanna

Submitted to: ASA-CSSA-SSSA Annual Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: August 3, 2009
Publication Date: November 1, 2009
Citation: Colaizzi, P.D., Kustas, W.P., Evett, S.R., Howell, T.A., Gowda, P. 2009. Daily evaptranspiration estimates by scaling instantaneous latent heat flux derived from a two-source model [abstract]. American Society of Agronomy, Crop Science Society of America, Soil Science Society of America 2009 Annual Meeting Abstracts, November 1-5,2009, Pittsburgh, Pennsylvania. 2009 CDROM.

Technical Abstract: Radiometric brightness temperature can be used in energy balance models that estimate sensible and latent heat fluxes of the land surface. However, brightness temperature is usually available only at one time of day when acquired from aircraft, fine-scale satellite platforms, or infrared thermometers aboard center pivot sprinkler systems. Therefore, a scaling method must be used to estimate daily evapotranspiration (ET) based on a one-time-of-day estimate of instantaneous latent heat flux. We compared three methods for scaling instantaneous latent heat flux estimated from a two-source (soil + vegetation) energy balance model to daily ET, against measured data by four large weighing lysimeters in Bushland, Texas. The scaling methods included the commonly used evaporative fraction and two versions of the Penman-Monteith equation (Standardized American Society of Civil Engineers method and a recursive method where surface temperature was estimated by iteration). Estimates of daily ET were compared to those measured by weighing lysimeters for various crops, and differences in the performance of scaling methods were evaluated and discussed.

Last Modified: 11/23/2014
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