Scale analysis of airborne flux measurements over heterogeneous terrain in a boreal ecosystem

Abstract

A wavelet analysis was applied to airborne flux measurements over a boreal ecosystem in Canada to investigate thermally induced mesoscale circulations and turbulent organized structures, which are according to large eddy simulation studies considered as one major reason for the energy balance closure problem. Fluxes of sensible heat, latent heat, carbon dioxide, and ozone were separated into a mesoscale and a small-scale turbulence part to quantify those flux contributions that cannot be captured with single-tower measurements. Mesoscale fluxes were comparable in magnitude to the energy balance residuals from ground-based tower measurements close to the flight track. A scale-dependent correlation analysis between the fluxes of different scalar quantities could not justify the common practice of correcting eddy covariance measurements of the sensible and the latent heat flux for the lack of energy balance closure according to the Bowen ratio or of correcting carbon dioxide fluxes according to the energy balance residual. Copyright 2007 by the American Geophysical Union.