ESTIMATION OF LATENT EVAPORATION FROM SIMPLE WEATHER OBSERVATIONS

Abstract

A technique for estimating daily latent evaporation from simple meteorological observations and astronomical data readily available from tables has been presented. From climatological records taken at six agricultural research establishments across Canada during 5 years, multiple regression equations were evolved to estimate daily latent evaporation from three to six variables. With observations of only maximum and minimum temperature available and extra terrestrial radiation from tables, the correlation coefficient with latent evaporation was highly significant (r = 0.68). The inclusion of any one or two of the variables solar energy, vapor pressure deficit, and wind resulted in correlation coefficients ranging from 0.75 to 0.81. With all six variables involved (r = 0.84) 70% of the variations of latent evaporation could be explained by variations of the meteorological parameters. The reliability of the estimates could be further improved if daily values of estimated latent evaporation were accumulated over a period of up to 16 days depending on the method employed.