Atmospheric boundary layer studies: From canonical representations to an integrative understanding

The knowledge of the atmospheric boundary layer that has been obtained in the past decades has mostly been acquired through study of the canonical cases in which the ABL manifests itself. In recent years, it is becoming clear that there are knowledge gaps that cannot be solved by studying these separate archetypes of the atmospheric boundary layer. Relevant processes that disrupt these archetypal ABLs are transitional periods, the role of surface heterogeneity and boundary-layer clouds, the interaction with larger (meso) and smaller atmospheric (micro) spatiotemporal scales and the role played by biochemical processes in regulating the surface turbulent fluxes. Contrary to our canonical view in representing these processes under quasi-stationary conditions and mean variables, we need to investigate the non-linear character among the processes in order to take their spatiotemporal correlations into account. In improving further our understanding, we need to incorporate biological processes responses, such as the stomatal aperture, since it regulates evapotranspiration, and chemical processes, such as the aerosol perturbation of radiative transfer in urban and rural areas. Consequently, our present and future research studies of the atmospheric boundary layer requires an approach that embeds multi-scale and multi-disciplinary fields.

Our presentation will show recent results of experimental field campaigns and fine-scale numerical experiments over grass fields, forests, crops and urban areas to discuss the current challenges in land-atmosphere interactions. First, we will introduce the topics and attempt to define where the challenges are. Subsequently, we will review how new instrumental devices, numerical simulation and analysis techniques enable us to investigate more effectively these subjects and transfer this knowledge to weather and climate models in order to integrate and represent the biochemical and physical processes occurring in the atmospheric boundary layer.