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Daily evaporation from drying soil: Universal parameterization with similarity
Author(s) -
Brutsaert Wilfried
Publication year - 2014
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 - 10.1002/2013wr014872
Subject(s) - exponential function , thermal diffusivity , soil water , evaporation , isothermal process , soil science , mathematics , inverse , similarity (geometry) , diffusion , environmental science , mathematical analysis , thermodynamics , geometry , physics , computer science , image (mathematics) , artificial intelligence
With supporting experimental evidence from three separate field studies of daily mean evaporation from bare soil with vastly different physical characteristics, it is shown that the process can be described as isothermal linear diffusion in a finite depth domain. The resulting solution leads directly to similarity variables and thus a universal parameterization, which should in principle be applicable to most field soils. In addition, a closed form expression is presented to estimate the weighted mean diffusivity for exponential type soil water diffusivities. In this solution, the widely used square root of inverse time proportionality of this phenomenon is its short time version, whereas the exponential decay proportionality, proposed however by several authors for vegetated surfaces, is its long time version. It appears that in many situations the soil layer contributing to evaporation is fairly shallow and only a few tens of centimeters thick.