The U.S. DOE Mesoscale to Microscale Coupling Project: Extending Boundary Layer Flow Simulation to Complex Environments

In support of development of next-generation high-fidelity wind plant simulation capabilities, the US DOE’s Atmosphere to Electrons (A2e) program has initiated the Mesoscale-Microscale Coupling (MMC) Project. The MMC project targets development, assessment, and validation of techniques to incorporate larger-scale atmospheric and environmental drivers of atmospheric flow variability into large-eddy simulations (LES) of the atmospheric boundary layer (ABL), for enhanced applicability to general meteorological and terrain conditions. The project is evaluating a range of existing and emerging techniques, from relatively simple nearly steady idealized LES using periodic lateral boundary conditions, to periodic LES forced internally with time varying mesoscale information, to LES fully coupled to mesoscale simulation output at its domain boundaries. Techniques to accelerate turbulence at inflow boundaries of fully-coupled LES, and use of an explicit canopy model in place of Monin-Obukhov similarity to enhance surface-layer dynamics, are explored. Simulation results are compared to observations in simple and complex meteorological and terrain settings. The efficacies and limitations of the various approaches to different types of ABL flow regimes examined thus far are presented, as well as recommendations for future research.