A novel method to convert daytime evapotranspiration into daily evapotranspiration based on variable canopy resistance

SummaryA method to convert daytime evapotranspiration (ET) into daily ET based on variable canopy resistance was investigated in this paper. The study was carried out for maize and canola crops grown in Coleambally Irrigation Area which is located in Murray Darling Basin of Australia. Variable canopy resistance was simulated on the basis of Todorovic method. This study has shown that the method performed well to scale daily ET from daytime ET measurements for both crops. In the case of the maize crop, the coefficient of determination (R2) was 0.979 and the index of agreement (d) was 0.981. In the case of the canola crop, the coefficient of determination (R2) was 0.936 and the index of agreement (d) was 0.960. Future work will focus on the study of this method to scale daily ET map from satellite-derived daytime ET map.

► A new method is proposed to upscale daily evapotranspiration (ET) from daytime ET.
► The method is based on variable canopy resistance derived from Todorovic model.
► The upscaled daily ET agreed well with daily ET measured from eddy covariance.
► The method need to be applied to regional ET model in the future work.