A Comparison of Methods for the Calculation of Potential Evapotranspiration Under the Windy Semi-arid Conditions of Southern Alberta

Abstract

Eight different, commonly used methods of calculating potential evapotranspiration (PE) were compared under different climatic conditions at the Agriculture Canada Research Station in Lethbridge, Alta. Under conditions of low wind speed and moderate humidity the methods produced similar results. However, under dry windy conditions estimates of PE differed widely. Equations that require the use of wind and especially humidity data as well as temperature and radiation data are recommended for estimates of PE in the chinook-dominated semi-arid climate of southern Alberta. Examination of two soil moisture models (SPAW and DBSW) demonstrated that simulation models often have specific requirements for type of PE estimate.