Abnormal data rejection range in the Bowen ratio and inverse analysis methods for estimating evapotranspiration.

Highlights • We proposed abnormal data rejection range that α times of supplied energy in Bowen ratio(B 0) and inverse analysis method(IABM). • We found the IABM has equally performance for estimation of evapotranspiration as well as B 0 method. • We found number of the rejection data were larger in B 0 method than in the IABM. • We found the proposed rejection range covers the previous researches of them. Abstract First, this paper proposes a definition of the abnormal data that occur as the Bowen ratio (B 0) approaches −1. The data are defined as α times of the heat flux supply (Rn - G), thus indicating the rejection range for the B 0. The method is applied to observed data. Second, we compare the results of the B 0 method with those of the inverse analysis of Bowen ratio method (IABM). The IABM can estimate the sensible and latent heat flux using temperature and humidity observed at a single height above the ground by optimization. Third, the estimation of the monthly evapotranspiration required for water resources and irrigation planning is adequate for α = 1˜3 in the B 0 method and IABM , and the initial humidity for IABM is adequate for 80% of the observed humidity plus 20%. Fourth, the features of the analysis of both methods regarding the direction of latent heat flux (lE) and sensible heat flux (H) associated with temperature difference (ΔT) and vapor pressure (Δe) clarified. And we found that the number of the rejected data in hourly and monthly is remarkably large in B 0 method than IABM. Based on above results, the IABM has almost the same performance compared with the B 0 method excluding initial value determination in the optimization process. [ABSTRACT FROM AUTHOR]