Coherent eddies and temperature structure functions for three contrasting surfaces. Part II: Renewal model for sensible heat flux

摘要: Sensible heat, latent and other scalar fluxes cannot be measuredwithin short dense canopies, e.g., straw mulches, with standard approachessuch as eddy correlation, Bowen ratio-energy balance, aerodynamic, andvariance methods. However, recently developed surface renewal models, thatare based on the fact that most of turbulent transfer within abovecanopies is associated large-scale coherent eddies, which are evidentas ramp patterns in time series, offer a feasible solution. Wepresent new air model calculates sensible heat flux atdifferent heights above canopy from average cubictemperature structure function, sampled at moderate rate, measuredaverage friction velocity. The calibrated tested datameasured Douglas-fir forest mulch andbare soil. We show describes half-hour variations ofsensible very well, both roughnesssublayers inertial sublayer, for stable unstable atmosphericconditions. combined empirical coefficient appears modelhas an apparently universal value about 0.4 all surfaces andheights, makes application particularly simple. Themodel used to predict daytime nighttime profileswithin small bare opening mulch.