Novel methodology to evaluate and compare evapotranspiration algorithms in an agroecosystem model

Abstract

Efforts to improve agroecosystem models require methods for unbiased comparisons among simulation algorithms. With focus on evapotranspiration (ET) in Cotton2K, the objectives were to develop a novel methodology for evaluating model parameterization options and to compare model performance using three ET algorithms. The Cotton2K model was updated to include a standardized ET method, and two Penman approaches were also tested. Sobol global sensitivity analysis and multiobjective optimization were used to identify influential parameters and select feasible parameterization options. The three ET methods led to differences in simulation accuracy for ET, soil water contents, and several plant growth metrics (p<0.05). However, no ET method could consistently outperform the other two methods, and ET simulation errors were up to 60%. The simulation methodology permitted unbiased comparison of three ET methods in Cotton2K and highlighted areas for model improvement, including the surface evaporation simulation and the linkage between simulated ET and crop growth.