Stable Boundary Layers and Subfilter-Scale Motions

Recent high-resolution large-eddy simulations (LES) of a stable atmospheric boundary layer (SBL) with mesh sizes N=(5123,10243,20483) or spacings ▵=(0.78,0.39,0.2) m are analyzed. The LES solutions judged to be converged based on the good collapse vertical profiles mean winds, temperature, and low-order turbulence moments, i.e., fluxes variances, increasing N. largest discrepancy is in stably stratified region above low-level jet. Subfilter-scale (SFS) motions extracted from N=20483 compared sonic anemometer fields horizontal array study (HATS) its sequel over ocean (OHATS). results simulation observations using dimensionless resolution ratio Λw/▵f where ▵f filter width Λw characteristic scale energy-containing eddies velocity. SFS span ranges 0.1<Λw/▵f<20 agreement. small, medium, large range correspond Reynolds-averaged Navier–Stokes (RANS), gray zone (a.k.a. “Terra Incognita”), fine-resolution LES. cuts across peak energy spectrum then flux parameterizations need adaptive account for partially resolved but also “stochastic” fluctuations that represent turbulent correlation between fluctuating rate strain tensors. data 20483 will made available research community through web tools provided by Johns Hopkins University Turbulence Database.