On the Sensitivity of Large-Eddy Simulations of the Atmospheric Boundary Layer Coupled with Realistic Large-Scale Dynamics

• DOI: 10.1175/mwr-d-23-0101.1
• Publication Date: 2024-02-26T11:12:52Z
• Authors: Paolo Giani; Paola Crippa
• Keywords: Large-Eddy Simulation

Abstract We present a new ensemble of 36 numerical experiments aimed at comprehensively gauging the sensitivity nested large-eddy simulations (LES) driven by large-scale dynamics. Specifically, we explore multiscale configurations Weather Research and Forecasting (WRF) Model to simulate boundary layer flow over complex topography Perdigão field site, with five domains discretized horizontal resolutions ranging from 11.25 km 30 m. Each member has unique combination following input factors: (i) initial conditions, (ii) subgrid turbulence modeling in gray zone turbulence, (iii) subgrid-scale (SGS) models LES, (iv) land-cover datasets. probe their relative importance for LES calculations velocity, temperature, moisture fields. Variance decomposition analysis unravels large sensitivities land-use datasets very weak SGS model. Discrepancies within members can be as 2.5 m s −1 time-averaged near-surface wind speed on ridge 10 without time averaging. At specific points, fraction this explained different domains. implement momentum budget routine WRF further elucidate mechanisms behind observed sensitivity, paving way an increased understanding tangible effects problem. Significance Statement Several science engineering applications, including turbine siting operations, weather prediction, downscaling climate projections, call high-resolution lowest part atmosphere. Recent studies have highlighted that such simulations, coupled models, are challenging require several important assumptions. With set experiments, evaluate compare significance assumptions outstanding challenges (i.e., coupling atmospheric simulations). The ultimate goal is put each individual assumption into wider perspective realistic problem quantify its compared other choices.