IMPACT OF SOIL-WATER PROPERTY PARAMETERIZATION ON ATMOSPHERIC BOUNDARY-LAYER SIMULATION

Both the form of functional relationships applied for soil water prope rties and the natural field-scale variability of such properties can s ignificantly impact simulation of the soil-plant-atmosphere system on a diurnal timescale. Various input parameters for soil water propertie s including effective saturation, residual water content, anerobiosis point, field capacity, and permanent wilting point are incorporated in to functions describing soil water retention, hydraulic conductivity, diffusivity, sorptivity, and the plant sink function. The perception o f the meaning of these values and their variation within a natural env ironment often differs from the perspective of the soil physicist, pla nt physiologist, and atmospheric scientist. This article investigates the sensitivity of energy balance and boundary layer simulation to dif ferent soil water property functions using the Oregon State University coupled atmosphere-plant-soil (CAPS) simulation model under bare soil conditions. The soil parameterizations tested in the CAPS model inclu de those of Clapp and Hornberger [1978], van Genuchten [1980], and Cos by et al. [1984] using initial atmospheric conditions from June 16, 19 86 in Hydrologic Atmospheric Pilot Experiment-Modelisation du Bilan Hy drique (HAPEX-MOBILHY). For the bare soil case these results demonstra te unexpected model sensitivity to soil water property parameterizatio n in partitioning all components of the diurnal energy balance and cor responding boundary layer development.