IDENTIFICATION OF TURBULENCE STRUCTURES ABOVE A FOREST CANOPY USING AWAVELET TRANSFORM

The wavelet transform is used to identify scales of large coherent str uctures present in atmospheric turbulence above the subarctic forest a t Schefferville. Individual coherent structures contributing to much o f the exchange between the forest and the atmosphere are depicted in t erms of both scale and location using contour diagrams of wavelet tran sform coefficients. Three typical case studies of turbulence and flux observations were selected to examine the physical characteristics of these flux-filled events and their evolution with distance away from t he forest canopy. A wavelet transform spectral technique is applied to vertical velocity, temperature, and turbulent heat flux data observed over the sparse coniferous forest to extract the relative importance of each scale present in those data series. The scale of turbulence st ructures in relation with their characteristic spacing is discussed.