VARIATION IN SOIL PARAMETERS - IMPLICATIONS FOR MODELING SURFACE FLUXES AND ATMOSPHERIC BOUNDARY-LAYER DEVELOPMENT

Soil texture can be heterogeneous; however for land surface-atmospheri c modeling purposes, it is often considered homogeneous at a particula r point and described by empirical equations which have been formulate d to describe 'average' hydraulic and thermodynamic processes in the s oil. Large deviations in the variables and coefficients used in these empirical equations have been previously documented. One of the coeffi cients is varied by plus-and-minus one standard deviation about its me an, and tested in a coupled atmospheric-plant-soil model. Results of m odel simulations show that the effects on surface fluxes and boundary- layer development are largest for dry to moderate Values of soil moist ure, particularly for bare soil conditions.