Internal equilibrium layer growth over forest

Friction velocity data from different heights above a forest are used to evaluate the influence from the surrounding landscape on forest micro-meteorological measurements under near-neutral conditions. Data are used from one field site and two forest sites. The field site data are used to estimate the magnitude of the scatter. Different theoretical friction velocity profiles for the Internal Boundary Layer (IBL) are tested against the forest data. The results yield information on the Internal Equilibrium Layer (IEL) growth and an equation for the IEL height fur neutral conditions is derived. For stable conditions the results indicate that very long fetches are required in order to measure parameters in equilibrium with the actual surface.