Near Real Time Evapotranspiration Estimation Using Remote Sensing Data
Abstract
Satellite remote sensing is a promising tool to estimate the spatial distribution of evapotranspiration (ET) at regional or global scales with minimal use of in situ observational data. A spatial mapping of the solar energy partition is the central challenge for ET estimation from satellite remote sensing data. We developed a near real time ET estimation system using MODIS data products. A "VI-Ts" (vegetation index and the surface radiant temperature) diagram is used to estimate soil temperature and air temperature. Downward short-wave radiation and cloud cover data are taken from GEWEX Continental Scale International Project (GCIP) and GEWEX Americas Prediction Project (GAPP) Surface Radiation Budget (SRB) Data. Other radiation components are calculated from remote sensing albedo, emissivity, and temperatures. The landscape is assumed to be a mixture of vegetation and bare soil. Therefore, a simple two-source model of ET is used. A canopy conductance model is used to describe vegetation physiology and to estimate vegetation ET. The temperatures are used to estimate bare soil evaporation. The near real time system is primarily driven by remote sensing data, yet is flexible enough to incorporate meteorological data when they are available. The near real time ET estimation system, which is housed at the University of Washington (UW) and runs in connection with the UW westwide seasonal streamflow prediction system, updates daily for a domain spanning the entire western United States.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2007
- Bibcode:
- 2007AGUFM.H31A0127T
- Keywords:
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- 1816 Estimation and forecasting;
- 1818 Evapotranspiration;
- 1855 Remote sensing (1640)