A thorough knowledge of the exchange of momentum, heat, moisture, and CO2 between forests and the atmosphere is essential in order to understand the role of forest ecosystems in the global atmospheric CO2 budget. In micrometeorology, the horizontal transport of momentum, heat, and moisture resulting from surface inhomogeneities is known as local advection. Because ideal homogeneous surface is rarely seen at the earth’s surface, neglect of advection due to surface inhomogeneity can lead to systematic errors in net ecosystem exchange(NEE) measurements.

The local advection of momentum, heat and moisture is numerically investigated by a 2-dimensional higher-order turbulence closure model which includes equations for the mean quantities, turbulent fluxes, and the viscous dissipation rate. The relative contributions from the eddy-covariance, mean advection, and storage are compared. The evolution of advection relative to eddy-covariance as a function of normalized downwind distance(x*=xK/uHc2) is examined. The results include the advective effects on turbulent flux distributions, surface energy balance, and evaporation rate.