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Determinants of the Asymmetric Parameter in the Generalized Complementary Principle of Evaporation
Author(s) -
Wang Liming,
Tian Fuqiang,
Han Songjun,
Wei Zhongwang
Publication year - 2020
Publication title -
water resources research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.863
H-Index - 217
eISSN - 1944-7973
pISSN - 0043-1397
DOI - 10.1029/2019wr026570
Subject(s) - evaporation , eddy covariance , sigmoid function , potential evaporation , environmental science , wind speed , covariance , ecosystem , atmospheric sciences , humidity , mathematics , hydrology (agriculture) , soil science , statistics , meteorology , physics , ecology , geology , geotechnical engineering , machine learning , artificial neural network , computer science , biology
The complementary principle, which was first proposed by Bouchet (1963), illustrates a complementary relationship among the actual evaporation, the potential evaporation, and the apparent potential evaporation. It has generated increasing attention for estimating evaporation by using only routinely observed meteorological variables (radiation, wind speed, air temperature, and humidity) without complex surface property parameters. However, this principle still poses great challenges because of the underlying uncertainties in estimating its critical parameter, namely, asymmetric parameter b . In this study, we adopted a sigmoid generalized complementary function and utilized the eddy covariance (EC) data from 217 sites around the world to determine b values in different ecosystems and their correlation with environmental factors. We found b has a mean value of 6.01 ± 0.08. The asymmetric parameter b is small in dry regions (i.e., the desert ecosystem, 0.42 ± 0.02) and increases as the land surface wetness improves. The ecosystem mean air temperature and vapor pressure deficit have negative correlations with b (Pearson correlation coefficients are −0.57 and −0.52, respectively), and the mean soil water content has a positive correlation with b (0.69). Besides, the sigmoid function has a favorable capability in estimating evaporation no matter based on the site‐specific b values or the ecosystem mean b values. The ecosystem mean b values given in the current study also perform acceptably in the independent verifications, indicating these values can be applied extendedly for regional and global studies.