15th Conference on Boundary Layer and Turbulence

13.3a

Some Improvements to Louis Surface Flux parameterization (Formerly paper number P5.5)

Shouping Wang, NRL, Monterey, CA; and Q. Wang and J. D. Doyle

Surface flux parameterization developed by Louis in 1978 had been widely used in meteorological models essentially because of its simplicity in formulation and non-iterative nature. This parameterization, however, has following weakness as discussed in some other papers: weak dependence on bulk Richardson number over smooth surfaces in convective conditions; lower values of transfer coefficients in low wind speeds in convective conditions; and overall inability dealing with different roughness lengths for momentum and heat transfer. This work aims at improving these undesirable features. For convective regimes, Louis scheme is tuned to match COARE2.6 parameterization developed by Fairall and Bradley group, which significantly improves the behavior of Louis scheme at low wind speeds and convective regime. We further use an approach similar to that of Uno et al. (1996) to address different momentum and heat roughness length issue. Finally, an analytical method is developed to solve z/L in the Monin-Obukhov similarity formulation by Beljaars and Holtslag (1996) under stable conditions. The effects of the new formulation on the boundary layer structure are discussed using NAVY░»s COAMPS model.

extended abstract  Extended Abstract (124K)

Session 13, Atmospheric Boundary Layer Parameterizations from Mesoscale to Macroscale
Thursday, 18 July 2002, 3:30 PM-5:30 PM

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