Estimates of Pan Evaporation from Mean Maximum Temperature and Vapor Pressure

Abstract An equation for estimating pan evaporation has been derived by regression analysis from climatic data of a number of widely separated stations in Australia. The required data are mean maximum temperature, mean vapor pressure, and day length. The equation resembles the bulk aerodynamic (mass transfer) expression, but does not contain a wind parameter. An empirical variate was postulated and compared with five other variates also available from limited data. Significance tests were applied to assess the likelihood that observed differences between correlations may have arisen through sampling. A number of cases are found with significantly (P<0.01) higher correlations in favor of the postulated empirical variate. For all the variates, the slopes and heights of individual reasons based upon data of specific stations often differed significantly (p<0.01) from those of a derived regression which best fitted the combined data from a number of stations. Regardless of the empirical variate considered for...