On the Brutsaert temperature roughness length model for sensible heat flux estimation

Abstract

The scalar roughness length for temperature, Z0(h), is necessary to estimate the sensible flux from atmospheric surface layer similarity theory in conjunction with skin temperature measurements. A theoretical relationship for Z0(h) as a function of the roughness Reynolds number Z0+ which was developed by Brutsaert [1975] for rough-bluff surfaces is often used to link infrared skin temperature measurements to atmospheric temperature measurements. Measurements of sensible heat flux and temperature at two semiarid sites are used to evaluate and test the temperature roughness length model coefficients. Consideration of the measurement error is important to derive an accurate set of coefficients. These new field-based coefficients correct for some of the underprediction of sensible heat flux at high flux rates that occurred with past formulations.