Accession Number : ADA282402

Title :   Marine Boundary-Layer Parameterizations for Large-Scale Models.

Descriptive Note : Final rept. 12 Feb 91-30 Apr 94,

Corporate Author : OREGON STATE UNIV CORVALLIS COLL OF OCEANIC AND ATMOSPHERIC SCIENCES

Personal Author(s) : Mahrt, L. ; Ek, M. ; Sun, J. ; Frech, M.

Report Date : 19 APR 1994

Pagination or Media Count : 235

Abstract : This report describes work on the PL atmospheric boundary-layer model conducted under contract number F19628-91-K-0002 from the Phillips Laboratory. This model was developed to provide turbulence parameterization schemes for a global numerical weather prediction model. In this report, boundary-layer nonlocal turbulent mixing is reexamined, and a nonlocal momentum mixing formulation is presented. The boundary-layer cloud formulation, that accounts for turbulent and subgrid-mesoscale moisture variations, is extended to include enhanced cloud mixing using moist conservative variables. Observational data and results from model simulations are used to examine the complex land-surface/atmosphere interactions and the potential for cloud development. Exchange coefficients for subgrid fluxes are shown to depend significantly on grid size in the presence mesoscale motion induced by surface heterogeneity. Tower and aircraft-measured fluxes over heterogeneous terrain are analyzed to show the spatial variation of surface fluxes and the effect on the surface exchange coefficients for area-averaged fluxes. The classical bulk aerodynamic method for estimating surface fluxes in terms of surface radiative temperature is examined. A new sea-surface roughness formulation includes the effects of aerodynamically smooth and rough flow, and wave age in terms of a simple wind tendency relation. Subgrid variability, Atmospheric boundary-layer, Surface fluxes, Boundary-layer model, Surface energy balance, Cloud cover parameterization, Ocean surface roughness

Descriptors :   *BOUNDARY LAYER, *ATMOSPHERE MODELS, *PARAMETERS, *SCALE MODELS, *WEATHER FORECASTING, AERODYNAMICS, AIRCRAFT, ATMOSPHERICS, BALANCE, BOUNDARIES, CLOUD COVER, CLOUDS, COEFFICIENTS, CONTRACTS, ENERGY, EXCHANGE, FLOW, FORMULATIONS, GLOBAL, GRIDS, HETEROGENEITY, INTERACTIONS, LABORATORIES, LAYERS, MIXING, MOISTURE, MOMENTUM, MOTION, OCEAN SURFACE, OCEANS, SURFACE ENERGY, SURFACE ROUGHNESS, SURFACES, TEMPERATURE, TERRAIN, TURBULENCE, VARIABLES, VARIATIONS, WEATHER, WIND, MARINE ATMOSPHERES, MATHEMATICAL PREDICTION, MARINE BIOLOGY.

Subject Categories : Fluid Mechanics
      Atmospheric Physics
      Meteorology

Distribution Statement : APPROVED FOR PUBLIC RELEASE