Soil Texture Effects on Surface Resistance to Bare-Soil Evaporation

P. Lehmann , O. Merlin (1) , P. Gentine , D. Or

1 CESBIO - Centre d'études spatiales de la biosphère

Modeling of surface energy balance and the separation of evapotranspiration to its component fluxes require quantification of evaporation from land surfaces. The nonlinear relationship between surface heat fluxes and the hydration state of soil surfaces present a challenge to remote estimation of surface evaporation rates. We study the often-overlooked role of soil properties in determining surface evaporation resistance. We present a framework for quantifying how the ratio of actual to potential evaporation rates varies with changes in surface water content for different soil textures. The model uses the evaporative characteristic length (a soil-dependent active depth of evaporation) and soil resistance to capillary flow across that region. Predictions were in good agreement with flux tower measurements of bare-soil evaporation from 10 soil textural classes. The study offers a simple and physically based method for incorporating surface evaporation resistance into land-surface models considering soil type and surface water content.

Keywords: water content; water content; soil evaporation; capillary flow; climate modeling; bare soil; surface resistance

Domains: Sciences of the Universe [physics]; Earth Sciences

P. Lehmann, O. Merlin, P. Gentine, D. Or. Soil Texture Effects on Surface Resistance to Bare-Soil Evaporation. Geophysical Research Letters, 2018, 45 (19), pp.10,398-10,405. ⟨10.1029/2018GL078803⟩. ⟨insu-03668271⟩