Linking the complementary evaporation relationship with the Budyko framework for ungauged areas in Australia

[摘要] While the calibration-free complementary relationship (CR) hasperformed excellently in predicting terrestrial evapotranspiration(ET a ) , how to determine the Priestley–Taylor coefficient ( α e ) is a remaining question. In this work, we evaluated this highlyutilizable method, which only requires atmospheric data, with in situ fluxobservations and basin-scale water-balance estimates (ET wb ) inAustralia, proposing how to constrain it with a traditional Budyko equationfor ungauged locations. We found that the CR method with a constant α e transferred from fractional wet areas performed poorly inreproducing the mean annual ET wb in unregulated river basins, and itunderperformed advanced physical, machine-learning, and land surface modelsin closing grid-scale water balance. This problem was remedied by linkingthe CR method with a traditional Budyko equation that allowed for an upscalingof the optimal α e from gauged basins to ungauged locations. Thecombined CR–Budyko framework enabled us to reflect climate conditions in α e , leading to more plausible ET a estimates in ungaugedareas. The spatially varying α e conditioned by local climatesenabled the CR method to outperform the three ET a models in reproducing thegrid-scale ET wb across the Australian continent. We argued here thatthe polynomial CR with a constant α e could result in biasedET a , and it can be constrained by a traditional Budyko equation forimprovement.

[学科分类] 妇产科学