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DOI	10.1029/2019MS001685
	Surface Flux Equilibrium Theory Explains an Empirical Estimate of Water-Limited Daily Evapotranspiration
	McColl K.A.; Salvucci G.D.; Gentine P.
发表日期	2019
ISSN	19422466
起始页码	2036
结束页码	2049
卷号	11 期号:7
英文摘要	Evapotranspiration (ET) plays a central role in the water, energy, and carbon cycles but is difficult to model and estimate due to its dependence on the heterogeneous land surface. Recent studies suggest that standard weather station atmospheric observations alone may be sufficient to estimate ET. This is surprising since ET over land is often strongly constrained by the land surface, for instance, by water limitation. While these studies have been empirically successful, a physical explanation for why this is possible has been lacking. Here, we provide a physical explanation for why one of these approaches—the ET from Relative Humidity at Equilibrium (ETRHEQ) method—works, using a simple model of a steady-state idealized atmospheric boundary layer. We show that, across a wide range of plausible parameter values, this model reproduces ETRHEQ, suggesting that it contains the essential physics that lead to ETRHEQ. We derive a closed-form expression for ETRHEQ at steady state and use it to show that ETRHEQ can be explained in terms of the near-surface relative humidity (RH) budget of the idealized model: in particular, it is equivalent to assuming a balance between surface moistening and heating terms in the RH budget. Negative feedbacks between surface fluxes (constrained by the surface energy budget) and atmospheric temperature and humidity mean that these terms typically balance, explaining the empirical success of ETRHEQ over a wide range of conditions. We define this state—in which the moistening and heating terms balance in the RH budget—as “surface flux equilibrium.”. ©2019. The Authors.
英文关键词	boundary layer meteorology; evapotranspiration; hydrometeorology; land-atmosphere coupling; water stress
语种	英语
scopus关键词	Atmospheric boundary layer; Budget control; Evapotranspiration; Meteorology; Surface measurement; Atmospheric observations; Closed-form expression; Daily evapotranspirations; Heterogeneous land surfaces; Hydrometeorology; Land-atmosphere couplings; Temperature and humidities; Water stress; Atmospheric humidity; boundary layer; empirical analysis; equilibrium; evapotranspiration; hydrometeorology; land surface; land-atmosphere interaction; meteorology; parameter estimation; surface flux; water stress
来源期刊	Journal of Advances in Modeling Earth Systems
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/156967
作者单位	Department of Earth and Planetary Sciences, Harvard University, Cambridge, MA, United States; School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, United States; Department of Earth and Environment, Boston University, Boston, MA, United States; Department of Earth and Environmental Engineering, Columbia University, New York, NY, United States
推荐引用方式 GB/T 7714	McColl K.A.,Salvucci G.D.,Gentine P.. Surface Flux Equilibrium Theory Explains an Empirical Estimate of Water-Limited Daily Evapotranspiration[J],2019,11(7).
APA	McColl K.A.,Salvucci G.D.,&Gentine P..(2019).Surface Flux Equilibrium Theory Explains an Empirical Estimate of Water-Limited Daily Evapotranspiration.Journal of Advances in Modeling Earth Systems,11(7).
MLA	McColl K.A.,et al."Surface Flux Equilibrium Theory Explains an Empirical Estimate of Water-Limited Daily Evapotranspiration".Journal of Advances in Modeling Earth Systems 11.7(2019).