|Hipps, Lawrence - UTAH STATE|
Submitted to: Agricultural and Forest Meteorology Conference Proceedings
Publication Type: Proceedings
Publication Acceptance Date: September 15, 1998
Publication Date: N/A
Technical Abstract: Monin-Obukhov similarity (MOS) theory has been a widely applied approach for estimating turbulent fluxes of heat and momentum in the surface layer and is used exclusively by Soil-Vegetation-Atmosphere-transfer (SVAT) models for simulating surface-atmosphere processes. However, a number of studies have shown significant discrepancies between turbulent fluxes derived from MOS and measured directly by eddy covariance for rough and heterogeneous surfaces (e.g., Chen and Schwerdtfeger 1989). In this paper, we discuss the application of MOS using mean profiles of temperature and wind speed for estimating sensible heat and momentum fluxes over a mesquite dune site in the USDA-ARS Jornada Experimental Rang near Las Cruces, New Mexico. This preliminary analysis of wind and temperature profiles over a heterogeneous and rough desert ecosystem indicates that application of MOS with mean gradients for predicting heat fluxes is generally unreliable. For this surface, it appears that the roughness sublayer, and other factors including the complicated source distribution for heat and other boundary layer processes more significantly affects the temperature profile compared to the wind. However, by using surface temperature as the boundary condition for predicting the heat flux the impact of surface roughness sublayer effects was reduced significantly.