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Importance of soil heating, liquid water loss, and vapor flow enhancement for evaporation
Author(s) -
Novak Michael D.
Publication year - 2016
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 - 10.1002/2016wr018874
Subject(s) - evaporation , loam , latent heat , sensible heat , airflow , flux (metallurgy) , moisture , flow (mathematics) , soil water , environmental science , mechanics , heat flux , water vapor , thermodynamics , hydrology (agriculture) , atmospheric sciences , meteorology , soil science , materials science , heat transfer , geotechnical engineering , geology , physics , metallurgy
Field measurements conducted by Cahill and Parlange (1998) are reanalyzed to verify if their conclusion that daytime peak values of 60–70 W m −2 of latent heat flux divergence occurred in the 7–10 cm soil layer of a drying Yolo silt loam when maximum values of surface latent heat flux are estimated to have been about 100 W m −2 . The new analyses, as similar to theirs as possible, are validated using a numerical simulation of coupled soil moisture and heat flow based on Philip and de Vries (1957) as a test bed. The numerical simulation is extended to include the flow of air induced by diurnal soil heating and evaporative water loss to verify the flux divergence calculations reported in Parlange et al. (1998) that explained the findings of Cahill and Parlange (1998). It is shown that the conclusions of both of these papers are in error, so that the original version of the Philip and de Vries (1957) theory is consistent with their field measurements after all and the effects of airflow associated with soil heating and liquid water loss (and low‐frequency barometric pressure variations also considered) are negligible in practice. In an additional investigation, enhancement of diffusive vapor flow (first postulated by Philip and de Vries (1957)) and discussed extensively in the literature since is shown to have negligible effects on cumulative evaporation under field conditions.