Parameterization of Evaporation from a Non-saturated Bare Surface for Application in Numerical Prediction Models

[摘要] Force restore treatment for the prediction of the surface volumetric soil water content proposed by Deardorff (1977) was applied to the precisely measured data of evaporation from the bare surface and soil water content close to the surface. Parameters C1, C2 and wb involved in the force restore method equation were investigated for the Kanto loam at Tsukuba, Japan.The results show that C1 monotonically decreases with an increase of the surface volumetric water content ws, and this relation is similar to that proposed by Deardorff (1978) for the Adelanto loam. The parameter C2 is not related to ws. It is suggested that C2 be taken as about 2 to 4 for the Kanto loam. It is shown that taking the soil water content at the depth of 1cm around 06JST as wb is effective for the further simplification of force restore treatment.Combination of the parameterization by the force restore method with the bulk method for the turbulent flux using the concept of surface moisture availability gives a good prediction of diurnal variations of evaporation and surface soil water content.

[学科分类] 大气科学