Variation in soil parameters: Implications for modeling surface fluxes and atmospheric boundary-layer development

Soil texture can be heterogeneous; however for land surface-atmospheric modeling purposes, it is often considered homogeneous at a particular point and described by empirical equations which have been formulated to describe 'average' hydraulic and thermodynamic processes in the soil. Large deviations in the variables and coefficients used in these empirical equations have been previously documented. One of the coefficients is varied by plus-and-minus one standard deviation about its mean, and tested in a coupled atmospheric-plant-soil model. Results of model simulations show that the effects on surface fluxes and boundary-layer development are larges for dry to moderate values of soil moisture, particularly for bare soil conditions.