9 July 2013 Improving temporal extrapolation for daily evapotranspiration using radiation measurements
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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.
© 2013 Society of Photo-Optical Instrumentation Engineers (SPIE)
Xiaochun Zhang, Xiaochun Zhang, Jingwei Wu, Jingwei Wu, Huayi Wu, Huayi Wu, Haorui Chen, Haorui Chen, Tong Zhang, Tong Zhang, } "Improving temporal extrapolation for daily evapotranspiration using radiation measurements," Journal of Applied Remote Sensing 7(1), 073538 (9 July 2013). https://doi.org/10.1117/1.JRS.7.073538 . Submission:
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