Estimating the evaporation in the Fenghuo Mountains permafrost region of the Tibetan Plateau

摘要

Accurate simulation of the daily actual evaporation (E) is important for understanding and predicting the hydrological climate and terrestrial water-carbon cycle. However, the inclement environment and sparse observation network in the high-altitude areas of the Tibetan Plateau hinder the reliable estimation of actual evaporation. The Complementary Relationship (CR) of evaporation, which is a simple method for estimating the actual evaporation implemented with only routine meteorological data, can be used to study the complex feedback between the atmosphere and the surface. In this study, the eddy covariance and meteorological data were used to test the existence of the CR in the Fenghuo Mountains in the permafrost regions of the Tibetan Plateau. We further compared the application of the generalized nonlinear CR (B2015) and the latest calibrationfree CR (S2017) in estimating the actual daily evaporation. The results show that a nonlinear CR of evaporation exists in the Tibetan Plateau. The calibration-free nonlinear principle implemented improvements in the boundary condition shows a more robustness advantage than the generalized method. In addition, we also found that, except rainfall, the freezing-thawing process of active layer is a main reason of seasonal variation characteristics in energy fluxes. These findings broaden our understanding of the applicability of the CR theory and provide a simple and promising method for simulating evaporation on the Tibetan Plateau with the minimum data sets.