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United States Department of Agriculture

Agricultural Research Service

Research Project: USING REMOTE SENSING & MODELING FOR EVALUATING HYDROLOGIC FLUXES, STATES, & CONSTITUENT TRANSPORT PROCESSES WITHIN AGRICULTURAL LANDSCAPES Title: Aerodynamic Temperature Derived from Flux-Profile Measurements and Two-Source Model Predictions over a Cotton Row Crop in an Advective Environment

Authors
item Chavez, Jose -
item Kustas, William
item Gowda, Prasanna
item Howell, Terry
item Prueger, John
item Hipps, Lawrence -
item O`shaughnessy, Susan
item Colaizzi, Paul
item Evett, Steven
item Neale, Christopher -
item Anderson, Martha
item Copeland, Karen

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: August 3, 2009
Publication Date: August 3, 2009
Citation: Chavez, J.L., Kustas, W.P., Gowda, P., Howell, T.A., Prueger, J.H., Hipps, L.E., Oshaughnessy, S.A., Colaizzi, P.D., Evett, S.R., Neale, C., Anderson, M.C., Copeland, K.S. 2009. Aerodynamic temperature derived from flux-profile measurements and two-source model predictions over a cotton row crop in an advective environment [abstract]. The International Annual Meetings of the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Symposium on Remote Sensing at Multiple Scales: The Bushland Evapotranspiration and Agricultural Remote Sensing Experiment. http://a-c-s.confex.com/crops/2009am/webprogram/Paper55678.html.

Technical Abstract: The surface aerodynamic temperature (SAT) is related to the atmospheric forcing conditions (radiation, wind speed and air temperature) and surface conditions. SAT is required in the bulk surface resistance equation to calculate the rate of sensible heat flux exchange. SAT cannot be measured directly and therefore is often replaced with a remotely-sensed surface temperature using a one-source energy balance modeling approach. However, field studies have shown that the relationship between aerodynamic and radiometric surface temperature is affected by many factors (e.g., leaf area index and surface heterogeneity), especially for partial-canopy surfaces, and hence significantly affects sensible heat flux estimation using flux-gradient approaches. In this study SAT for a cotton row crop was estimated using wind and temperature profile measurements along with eddy covariance measurements of turbulent heat and momentum fluxes. A two-source (soil + vegetation) energy balance model using radiometric surface temperature also provides an estimate of the aerodynamic temperature when solving for the canopy and soil temperatures and turbulent exchange of the soil and vegetation components under the imposed atmospheric forcing conditions. A comparison is made using flux-profile methods to estimate SAT, empirical equations derived from field measurements, and the two-source energy balance model estimates. Implications of the aerodynamic-surface radiometric temperature relationship on evapotranspiration estimates under BEAREX08 field conditions for surface energy balance modeling using remotely sensed surface temperature will be discussed.

Last Modified: 4/24/2014
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