Nonlocal Convective PBL Model Based on New Third- and Fourth-Order Moments

• DOI: 10.1175/jas3474.1
• Publication Date: 2005-08-11T15:19:40Z
• Authors: Y. Cheng; V. M. Canuto; A. M. Howard
• Keywords: Cumulant; Closure (psychology); Convective Boundary Layer

Abstract The standard approach to studying the planetary boundary layer (PBL) via turbulence models begins with first-moment equations for temperature, moisture, and mean velocity. These entail second-order moments that are solutions of dynamic equations, which in turn third-order moments, so on. How where terminate (close) has not been a generally agreed upon procedure variety differ precisely way they sequence. This can be viewed as bottom-up approach. In this paper, top-down is suggested, worked out, justified, new closure model proposed fourth-order (FOMs). key reason consideration availability aircraft data provide first time z profile several FOMs. FOM expressions have nonzero cumulants relates integrals (TOMs), giving rise nonlocal based on an analysis TOM aid large-eddy simulation (LES) data, verified by comparison data. Use FOMs TOMs yields model, damped more realistically than previous models. Surprisingly, simplify, rather complicate, compared quasi-normal (QN) approximation, since resulting analytic considerably simpler those free algebraic singularities. employed moment (SOM) numerical convective PBL run, potential temperature T, SOMs, LES As final consistency check, substituted from run back into FOMs, again