The Mechanism of Sensible Heat Transfer in and above a Forest

Abstract

The atmosphere-forest heat exchange mechanism was investigated based on the measurement applying eddy correlation method at 3 heights above and 2 heights inside the canopy of a coniferous forest. Counter gradient or zero gradient sensible heat transport was observed inside the canopy. Cospectral analysis indicates that this counter gradient flux is caused by the high frequency eddies, suggesting that the penetrating cold temperature gusts are contributing to this phenomena. Large eddies are contributing to the co-gradient flux even in the canopy. A 2nd order turbulence closure model for a horizontally homogeneous field was applied to compare with the observation. For the wind from the valley, the observed temperature profiles and sensible heat flux agreed with the computation. However, for the wind from the ridge, the observed temperature field suggested the occurrence of drainage flows which are not expressed by the computation. © 2004, The Society of Agricultural Meteorology of Japan. All rights reserved.