Comparison of evapotranspiration variables in Evapotranspiration Maps for Australia with commonly used evapotranspiration variables

The Australia Bureau of Meteorology and the Cooperative Research Centre for Catchment Hydrology released a set of Evapotranspiration Maps for Australia in July 2001 as part of the Bureau’s Climatic Atlas Series. The maps give average monthly and annual values of three evapotranspiration (ET) variables: point potential evapotranspiration (PPET), areal potential evapotranspiration (APET) and areal actual evapotranspiration (AAET). This paper compares the average annual and seasonal values of the ET variables in the ET Maps with three commonly used ET variables, using data from 55 locations in Australia. The comparisons indicate that the PPET is similar to class A pan evaporation and can be used as a substitute for class A pan evaporation. The APET is similar to the Priestley-Taylor ET, except in north-east Australia where the APET is about 20% higher than the Priestley-Taylor ET. The APET in the coastal areas is also similar to the FAO56 reference crop evapotranspiration (ETo) and can be used as an approximate estimate of ETo in the coastal areas.