Convection Cells in the Planetary Boundary Layer: Origin and Reduced Modeling

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Under free-convection conditions, the flow in the planetary boundary layer is organized in long-lived, large-scale cellular motions. We want to investigate these superstructures. In particular, we want to ascertain how important the boundary conditions are for their formation and evolution, and how we can represent them in simple atmospheric models. We will employ data from direct numerical simulations. Starting from Rayleigh-Bénard convection, we will incrementally modify the boundary conditions to design and study convective boundary layers, which are idealized configurations that reproduce key aspects of the atmospheric flow. The aim is to understand the dependence of superstructures on the boundary conditions, and on the Rayleigh number. For the detection of the superstructures and the analysis of their interaction with the small-scale turbulence, we will use coarse-graining and Lagrangian techniques. As an outcome of this work, we will comprehensively learn how efficient these techniques are to represent superstructures in the planetary boundary layer. Besides, this project will bring together Rayleigh-Bénard convection and atmospheric convection in one single analysis, assessing thereby to what extent we can transfer knowledge between the two fields.