Evaluation of three energy balance-based evaporation models for estimating monthly evaporation for five lakes using derived heat storage changes from a hysteresis model

Abstract

The heat storage changes (Qt) can be a significant component of the energy balance in lakes, and it is important to account for Qt for reasonable estimation of evaporation at monthly and finer timescales if the energy balance-based evaporation models are used. However, Qt has been often neglected in many studies due to the lack of required water temperature data. A simple hysteresis model (Qt = a*Rn + b + c*dRn/dt) has been demonstrated to reasonably estimate Qt from the readily available net all wave radiation (Rn) and three locally calibrated coefficients (a–c) for lakes and reservoirs. As a follow-up study, we evaluated whether this hysteresis model could enable energy balance-based evaporation models to yield good evaporation estimates. The representative monthly evaporation data were compiled from published literature and used as ground-truth to evaluate three energy balance-based evaporation models for five lakes. The three models in different complexity are De Bruin-Keijman (DK), Penman, and a new model referred to as Duan-Bastiaanssen (DB). All three models require Qt as input. Each model was run in three scenarios differing in the input Qt (S1: measured Qt; S2: modelled Qt from the hysteresis model; S3: neglecting Qt) to evaluate the impact of Qt on the modelled evaporation. Evaluation showed that the modelled Qt agreed well with measured counterparts for all five lakes. It was confirmed that the hysteresis model with locally calibrated coefficients can predict Qt with good accuracy for the same lake. Using modelled Qt as inputs all three evaporation models yielded comparably good monthly evaporation to those using measured Qt as inputs and significantly better than those neglecting Qt for the five lakes. The DK model requiring minimum data generally performed the best, followed by the Penman and DB model. This study demonstrated that once three coefficients are locally calibrated using historical data the simple hysteresis model can offer reasonable Qt to force energy balance-based evaporation models to improve evaporation modelling at monthly timescales for conditions and long-term periods when measured Qt are not available. We call on scientific community to further test and refine the hysteresis model in more lakes in different geographic locations and environments.