Understanding future potential evapotranspiration changes in Zhejiang Province, East China

Dr. Yueping Xu

Zhejiang University

Abstract: Potential evapotranspiration is an important component of hydrological modeling. In this study, the objective is to project potential evapotranspiration in the future period 2011-2040 and understand their changes in Zhejiang Province, East China. The sensitivity of potential evapotranspiration to five climatic variables (solar radiation, daily minimum and maximum air temperature, relative humidity and wind speed) is analyzed based on observation data from 1955-2008  using a global sensitivity analysis method, Sobol’s method. The changes in potential evapotranspiration during the future period are generated using one regional climate model, PRECIS with two global climate models - ECHAM5 and HadCM3, and their causes are analyzed based on sensitivity analysis results. Global sensitivity analysis results reveal substantial spatial-temporal variations in the sensitivity of potential evapotranspiration to climatic variables and unignorable interactions among climatic variables. Rather similar spatial change patterns of annual mean PET are generated for both GCMs; however, seasonal or monthly changes are very different due to different spatial-temporal changes in climatic variables. Different contributory sources to potential evapotranspiration changes are identified at different months and stations; the PET changes in 2011-2040 are mainly due to three climatic variables including solar radiation, relative humidity and daily minimum temperature.