TRANSPORT-DISSIPATION ANALYTICAL SOLUTIONS TO THE E − ǫ TURBULENCE MODEL AND THEIR ROLE IN PREDICTIONS OF THE NEUTRAL ABL

E−ǫ turbulence model predictions of the neutral atmospheric boundary layer (NABL) are reinvestigated to determine the cause for turbulence overpredictions found in previous applications. Analytical solutions to the coupled E and ǫ equations for the case of steady balance between transport and dissipation terms, the dominant balance just below the NABL top, are derived. It is found that analytical turbulence profiles laminarize at a finite height only for values of closure parameter ratio κ ≡ cǫ2σǫ/σe equal to or slightly greater than one, with laminarization as z → ∞ for greater κ . The point κ = 2 is additionally found that where analytical turbulent length scale (l) profiles made a transition from ones of decreasing (κ < 2) to increasing (κ > 2) values with height. Numerically predicted profiles near the NABL top are consistent with analytical findings. The height-increasing values of l predicted throughout the NABL with standard values of closure parameters thus appear a consequence of κ ≈ 2.5 (> 2), implied by these values (cǫ2 = 1.92, σǫ = 1.3, σe = 1). Comparison of numerical predictions with DNS data shows that turbulence overpredictions obtained with standard-valued parameters are rectified by resetting σǫ and σe to ≈1.1 and 1.6, respectively, giving, with cǫ2 = 1.92, κ ≈ 1.3, and laminarization of the NABL’s capping transport-dissipation region at a finite height.