Abstract: Accounting for the current knowledge of the Planetary Boundary Layer (PBL) structure and characteristics, a new set of turbulence parameterizations to be used in meso-scale meteorological models has been developed. That is, expressions for the vertical profiles of the eddy diffusion coefficient Ki (i = u, v, w) are implemented. Using the classical statistical diffusion Taylor’s theory [5], and observed spectral properties and characteristics of energy containing eddies are employed to estimate these parameters [1]. The results of this scheme are shown to agree with previously used parameterizations, and observations too. These parameterizations give continuous values for the PBL at all levels 0 < z < h, and all stability conditions: -infinity < L < infinity, where h is the PBL height and L is the Monin-Obukhov length. The new parameterizations are implemented in the B-RAMS, a meso-scale meteorological model [3]. Finally, a validation of the present parameterization is compared with other parameterizations: Smagorinsky [4] and Mellor-Yamada [2], and observational data collected from the Large Scale Biosphere (LBA) experiment.

References:

[1] Degrazia, G. A., Anfossi, D., Carvalho, J. C., Tirabassi, T., Campos Velho, H. F. (2000): Turbulence Parameterization for PBL Dispersion Models in All Stability Conditions, Atmospheric Environment, 34(21), 3575–3583.

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[4] Smagorinsky, J. (1963): General circulation experiments with the primitive equations: I. the basic experiment, Mon. Weather Rev., 91, 99–164.

[5] Taylor, G. I. (1921): Diffusion by continuous movements. Proc. Lond. Math. Soc., 2(20), 196–212.