Boundary Layer Flows and Turbulent Exchange over Heterogeneous and Complex Surfaces

Turbulent transport is the most important exchange mechanism for mass, momentum and heat in the atmospheric boundary layer. Understanding this mechanism above rough and heterogeneous terrain is key to accurately predict wind speed, temperature and trace gas concentrations above such surface. Turbulent exchange and its governing processes over horizontally homogeneous and flat surfaces are well described. Over realistic heterogeneous surfaces such as mountainous regions, however, additional processes and their influence on turbulence need to be considered. These include the presence of thermally-driven wind systems and the direct influence of tall vegetation in the roughness-sublayer. Surface heterogeneity also raises the question of representativeness for measurements and numerical models, where simplifications are necessary at all scales.

The goal of this session is that researchers focusing on boundary layer exchange processes above different types of canopy and terrain discuss strategies and potential pitfalls in measuring and modeling turbulent flow and turbulent fluxes above heterogeneous and complex surfaces.