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Evapotranspiration estimation using SMAP soil moisture products and bouchet complementary evapotranspiration over Southern Great Plains
- Walker, Elisabet, García, Gabriel A., Venturini, Virginia
- Journal of arid environments 2019 v.163 pp. 34-40
- dry environmental conditions, equations, evapotranspiration, semiarid zones, soil water, wind speed, Great Plains region
- Evapotranspiration (ET) is an important water withdrawal in the water balance, particularly in arid and semiarid regions. In this study, a formulation to derive the relative evapotranspiration (β) and ET from in situ and passive microwave data, is presented. The original Komatsu's β equation was modified by introducing a calibration parameter to eliminate the wind speed effects. Then, a simple formulation to estimate mean daily ET was obtained by combining the β parameter, Bouchet's complementary relationship, and Priestley-Taylor's equation. Estimates of β and ET were compared with ground observations in the study area, Southern Great Plains (SGP). These comparisons suggest that β characterizes the relative evapotranspiration behavior in the region. Besides, ET results show a good agreement with ground data, yielding a root mean square error and bias of 28.5 and −6 W/m2, respectively. The proposed approach took advantages of passive microwave images, combining them with ground observations in a simple and robust equation.