Remote sensing ET of alfalfa using a surface aerodynamic temperature model

José L. Chávez, Dale Straw, Luis A. Garcia, Thomas W. Ley, Allan A. Andales, Lane Simmons, Michael E. Bartolo, Christopher M.U. Neale

Research output: Chapter in Book/Report/Conference proceedingConference contribution

1 Scopus citations

Abstract

Accurate estimates of spatially distributed evapotranspiration (ET) using remote sensing algorithms could potentially improve crop water management. In addition, seasonal ET values could be used in assessing irrigation project efficiency, water use efficiency, ground water depletion, and the use of water rights over large irrigated areas. In this study, ET was mapped using airborne remote sensing model (SAT-ET) which uses inputs such as surface reflectance and radiometric surface temperature (Ts), and a surface aerodynamic temperature (To) sub-model. The SAT-ET model for irrigated alfalfa in Colorado was developed using surface temperature, horizontal wind speed and air temperature profile measurements, and with measurements of turbulent sensible heat fluxes (H) acquired with a Large Aperture Scintillometer (LAS). Estimates of the remote sensing-based ET for a 4.0 hectare alfalfa field, during the 2009 cropping season, were evaluated using a large weighing lysimeter (3.0 x 3.0 x 2.4 m) located at the Colorado State University (CSU) Arkansas Valley Research Center (AVRC) in Rocky Ford, CO. Hourly alfalfa ET was very well estimated with small errors of -5.8 to 1.1% while larger errors were found for estimates of daily ET (-13.5 to 17.8%). The To sub-model is very promising; however it needs to be further developed incorporating a wider range of crops and environmental and atmospheric conditions. Furthermore, the mechanism to extrapolate hourly to daily ET values needs to be investigated as well as the method to calculate reference ET for the conditions encountered in eastern Colorado.

Original languageEnglish (US)
Title of host publicationASABE - 5th National Decennial Irrigation Conference 2010, Held in Conjunction with Irrigation Show 2010
Pages798-808
Number of pages11
StatePublished - 2010
Externally publishedYes
Event5th National Decennial Irrigation Conference 2010, Held in Conjunction with Irrigation Show 2010 - Phoenix, AZ, United States
Duration: Dec 5 2010Dec 8 2010

Publication series

NameASABE - 5th National Decennial Irrigation Conference 2010, Held in Conjunction with Irrigation Show 2010
Volume2

Conference

Conference5th National Decennial Irrigation Conference 2010, Held in Conjunction with Irrigation Show 2010
Country/TerritoryUnited States
CityPhoenix, AZ
Period12/5/1012/8/10

Keywords

  • Aerodynamic temperature
  • Energy balance
  • Evapotranspiration
  • Remote sensing

ASJC Scopus subject areas

  • Agronomy and Crop Science

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