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Journal of Applied Remote Sensing

Improving temporal extrapolation for daily evapotranspiration using radiation measurements
Author(s): Xiaochun Zhang; Jingwei Wu; Huayi Wu; Haorui Chen; Tong Zhang
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Paper Abstract

Accuracy needs to be improved when extrapolating instantaneous remote sensing evapotranspiration (ET) values for daily ET estimates. Daily net radiation (R n24 ) is a critical variable for this extrapolation. We expand the de Bruin and Sticker formula for R n24 in the evaporative fraction method by incorporating ground radiation measurements. In addition, an improved daily transmittance formula that considers atmospheric conditions and solar declination is proposed for R n24 calculation. The coefficient for daily net longwave radiation (R nl24 ) in R n24 is regressed from the ground radiation measurements and the improved daily transmittance values. A comparative study was conducted in the Haihe River basin, China. Experimental results show that the improved method yields a root mean square error of 0.97 mm for daily ET and only about 2% underestimation for actual seasonal ET in the study area. These results are better than the values obtained by traditional methods.

Paper Details

Date Published: 9 July 2013
PDF: 21 pages
J. Appl. Remote Sens. 7(1) 073538 doi: 10.1117/1.JRS.7.073538
Published in: Journal of Applied Remote Sensing Volume 7, Issue 1
Show Author Affiliations
Xiaochun Zhang, Wuhan Univ. (China)
Jingwei Wu, Wuhan Univ. (China)
Huayi Wu, Wuhan Univ. (China)
Haorui Chen, China Institute of Water Resources and Hydropower Research (China)
Tong Zhang, Wuhan Univ. (China)

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