Estimation of evaporation rates in arid regions using an improved inverse analysis method

Arid regions cover approximately 41% of the Earth’s land surface, and water scarcity is a critical challenge for the populations living in these regions. Evaporation is an important component of crop water requirements and plays a significant role in ground surface energy exchange and climate change. This study improves a previously proposed inverse analysis method for estimating evaporation in arid regions by considering the distinct locations of sensible and latent heat transfer. In arid environments, sensible heat is transferred at the ground surface, whereas latent heat transfer associated with evaporation occurs below the ground surface. To represent this difference, a new relationship, CE = BeCH (CH: bulk transfer coefficient for sensible heat, CE: bulk transfer coefficient for latent heat, Be: evaporation efficiency), was incorporated into the model. The proposed method was evaluated using FLUXNET2015 data from four sites in the U.S.A. and three sites in Australia at hourly, daily, monthly, and annual time scales. The results generally showed good agreement between the estimated and observed evaporation values across all time scales, demonstrating the applicability of the proposed inverse analysis method to arid regions. The introduction of Be provides a physically meaningful representation of the reduced efficiency of evaporation under dryland conditions and offers a new perspective for evaporation estimation in arid environments.