Turbulent Prandtl Number in Stably Stratified Atmospheric Boundary Layer: Intercomparison between LES and SHEBA Data

摘要: Turbulence-resolving modelling technique, widely known as large-eddy simulation (LES), becomes a popular tool to investigate environmental turbulence and aggregate the impact of turbulent mixing on larger, meteorologically important scales. Although LES are proved be useful, technique still needs careful validation against available data sets. In research stably stratified layers, one key questions is relative efficiency for heat, mass momentum. Turbulence could measured by Prandtl number, Pr. It defined ratio eddy viscosity temperature diffusivity. Increase Pr with increasing stability, through gradient Richardson observed both in atmospheric field experiments (e.g. SHEBA data) resolving data. At same time, decrease decay intensity, flux number non-dimensional height. This fact indicates more significant role heat conductivity boundary possibly due momentum loss irradiation internal gravity waves, which partially offset general suppression exchange strong static stability. One practically consequence intensive than it would under constant that surface atmosphere always remain dynamically coupled. coupling prevents cooling values (-80 o C or so) characterizing radiative equilibrium, thus significantly warming polar climates. Direct observational studies difficult generally committed only within shallow layer. Laboratory rarely reach stabilities. these circumstances, homogeneous, high quality covering entire layer potentially great significance theoretical well parameterization design. this paper, we show first time numerical good agreement across large span Despite fact, discrepancies remain. The have been very weakly strongly cases where correspondingly observations simulations achieve.