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Improved methods for estimating monthly and growing season ET using METRIC applied to moderate resolution satellite imagery
Author(s) -
Kjaersgaard J.,
Allen R.,
Irmak A.
Publication year - 2011
Publication title -
hydrological processes
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.222
H-Index - 161
eISSN - 1099-1085
pISSN - 0885-6087
DOI - 10.1002/hyp.8394
Subject(s) - environmental science , satellite , satellite imagery , precipitation , evapotranspiration , image resolution , water balance , remote sensing , scale (ratio) , meteorology , climatology , computer science , geology , geography , cartography , aerospace engineering , artificial intelligence , engineering , biology , ecology , geotechnical engineering
Satellite‐based algorithms based on surface energy balance are now routinely applied to produce evapotranspiration (ET) products on an operational basis for use in water resources management. Landsat satellite imagery, or imagery with similar spatial resolution, is commonly used to produce estimates of ET at field scale because of the presence of an onboard thermal imager and the high spatial resolution of the imagery. The downside of using high‐resolution imagery is less frequent image acquisition. As a result, monthly and ultimately seasonal ET estimates may be based on only one or two satellite image snapshots per month. A potential shortfall in basing integrated ET averages on periodic snapshots from satellites is that local or regional precipitation events antecedent to the satellite images may unduly dominate the ET image, or conversely, effects may be absent from the image, and therefore the image‐based product may not represent evaporation from rainfall averaged over the monthly period. Methods for accounting for precipitation events when interpolating from daily to seasonal or longer periods are presented, including a recently developed soil‐water balance procedure that adjusts the ET derived from the satellite overpass date for background evaporation from soil caused by rainfall over monthly or longer integration periods. The result of the adjustment is an ET image and consequently final ET map that better represents the average evaporative conditions over the period. Copyright © 2011 John Wiley & Sons, Ltd.