Abstract: By using Eulerian second-order closure model, this paper studied the source-sink distribution and flux characteristics of sensible heat within forest canopy under atmospheric thermally stratified condition. In the daytime, a notable feature for the atmospheric stratification of forest canopy was the unstable stratification above the canopy and the stable stratification under the canopy. The changes of temperature profile indicated there was a ‘hot spot’ at about 2/3 of canopy height. The counter-gradient fluxes within the canopy were discoered by modeling the heat flux under weak stable atmospheric condition. Simulations of the diurnal variation of sensible heat flux were consistent with the measurements (R²=0.9035, P<0.01). Adding buoyancy in the sensible heat balance equation could increase the simulation accuracy of inversion model, and improve the simulation capability for heat flux balance.

Key words: second-order closure model, atmospheric thermally stratified condition, forest canopy, flux transport, amino acid, bioavailability, plantsoilmicroorganism.