Impact of terrain heterogeneity on near-surface turbulence structure

Clément Fesquet, Philippe Drobinski, Christian Barthlott, Thomas Dubos
2009 Atmospheric research  
This study investigates the impact of terrain heterogeneity on local turbulence measurements using 18 months of turbulence data taken on a 30 m tower at the SIRTA mixed land-use observatory under varying stability conditions and fetch configurations. These measurements show that turbulence variables such as the turbulent kinetic energy or momentum fluxes are strongly dependent on the upstream complexity of the terrain (presence of trees or buildings, open field). However, using a detection
more » ... ique based on wavelet transforms which permits the isolation of the large-scale coherent structures from small-scale background fluctuations, the study shows that, for all stability conditions, whatever the upstream complexity of the terrain, the coherent structures display universal properties which are independent of the terrain nature: the frequency of occurrence, time duration of the coherent structures, the time separation between coherent structures and the relative contribution of the coherent structures to the total fluxes (momentum and heat) appear to be independent of the upstream roughness. This is an important result since coherent structures are known to transport a large portion of the total energy.
doi:10.1016/j.atmosres.2009.06.003 fatcat:oeh6aqyvpnfyfl7pqs5tbjb3fm