A NEW METHOD FOR ESTIMATION OF SENSIBLE HEAT-FLUX FROM AIR-TEMPERATURE

A new method has been proposed for estimating sensible heat flux from single-level measurement of air temperature. When turbulent transfer o f heat in the lower atmosphere over a homogeneous surface is modeled b y a one-dimensional diffusion equation with a constant diffusivity, he at flux can be expressed as a weighted average (half-order derivative) of the time history of air temperature. This formula provides an appr oximate solution of the diffusion equation where the (eddy) diffusivit y characterizing the turbulent flow is not constant. Eddy diffusivity has been formulated based on Monin-Obukhov similarity theory with Busi nger-Dyer stability functions or determined by an empirical equation. The knowledge of surface parameters including friction velocity someti mes is needed to apply this method. The method was tested against obse rvations collected during two field experiments, FIFE and ABRACOS. The close agreement between the estimated sensible heat flux and observat ions suggests that this novel approach is a potentially powerful tool in evaluating the energy balance at the land surface.