Sensible heat flux estimation by flux variance and half-order time derivative methods

This study is the first to contrast two similarity theory methods, the flux variance and the half-order time derivative, over a wide range of atmosphe ric stability and surface roughness conditions. These two methods were sele cted because they require only single-level temperature measurement to esti mate sensible heat flux. The data used were collected over bare soil, a gra ss-covered forest clearing, and an even-aged pine forest. For all three sit es the flux variance method estimated the sensible heat flux relatively wel l for unstable atmospheric conditions. The half-order time derivative metho d was found to be sensitive to the parameterization of the eddy diffusivity , especially for the grass and bare soil field sites. Overall, the flux var iance method was able to reproduce the measured sensible heat flux with gre ater accuracy than the half-order time derivative methods for the three exp eriment sites.