Comparative Study of Various Formulations of Evaporations from Bare Soil Using In Situ Data

Abstract

Vajious formulations of surface evaporation are tested against in situ data collected over a plot of loamy bare ground. Numerical simulations lasting seven days are compared with observations of near-surface water content and cumulative evaporation. A comparison of classical bulk aerodynamic formulations shows similar predictions of daytime evaporation while significant differences are exhibited during the night. The so-called "surface moisture availability method" seems to overestimate the nocturnal evaporation flux. In the context of this dataset, threshold methods strongly underestimate surface evaporation during the whole period of observations. A sensitivity analysis reveals that threshold evaporation (maximum sustainable water flux) is highly sensitive upon the depth of the top soil layer.