Abstract
Measurements of sensible heat flux, radiometric surface temperature, air temperature, and wind speed made at eight semiarid rangeland sites were used to investigate the sensible heat flux-aerodynamic resistance relationship. The individual sites covered a wide range of vegetation (0.1–4 m tall) and cover (3%–95% bare soil) conditions. Mean values of kB−1, a quantity related to the resistance of heat versus momentum transfer at the surface, for the individual sites varied between 3.5 and 12.5. A preliminary test of the utility of an excess resistance based on the mean value of kB−1 showed that the difference between the mean estimated and measured sensible heat fluxes varied ±60 W m−2 for the eight semiarid sites. For the eight sites the values of kB−1 were plotted against the roughness Reynolds number. The plot showed considerable scatter with values ranging between and beyond the theoretical curves for bluff rough and permeable rough surfaces.
