||Non-Local Closure Model for Vertical Mixing in the Convective Boundary Layer.
Pleim, J. E. ;
Chang, J. S. ;
||National Oceanic and Atmospheric Administration, Research Triangle Park, NC. Atmospheric Sciences Modeling Div. ;State Univ. of New York at Albany. Atmospheric Sciences Research Center.;Environmental Protection Agency, Research Triangle Park, NC. Atmospheric Research and Exposure Assessment Lab.
Atmospheric boundary layer ;
Air pollution ;
Environmental transport ;
Convection currents ;
Atmospheric diffusion ;
Vertical air currents ;
Nitrogen oxides ;
Mesoscale phenomena ;
Asymmetrical Convection Model ;
Regional Acid Deposition Model
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||A simple non-local closure model for vertical mixing in Convective Boundary Layers (CBL) has been developed specifically for application in regional or meso-scale atmospheric chemistry models. The model, named the Asymmetrical Convective Model (ACM), is based on the concept that vertical transport within the CBL is inherently asymmetrical. Upward transport by buoyant plumes originating in the surface layer is simulated by mixing from the lowest model layer directly to all other layers in the CBL. Downward transport, however, proceeds only to the next lower layer in order to emulate gradual compensatory subsidence. The realism of the ACM is tested through comparisons to large-eddy simulations of several idealized test cases. The ACM is also tested in the context of the Regional Acid Deposition Model (RADM) both to determine sensitivity to different CBL mixing schemes and to compare to vertically resolved aircraft measurements. These tests demonstrate quicker upward transport of ground level emissions by the ACM as compared to the eddy diffusion scheme currently used in RADM. The ACM also affects ozone photochemistry in the boundary layer resulting in lower ozone concentrations in areas of high NOx emissions.
||Pub. in Atmospheric Environment, v26A n6 p965-981 1992. See also PB93-212702 and PB91-233551. Prepared in cooperation with State Univ. of New York at Albany. Atmospheric Sciences Research Center. Sponsored by Environmental Protection Agency, Research Triangle Park, NC. Atmospheric Research and Exposure Assessment Lab.
|NTIS Title Notes
||Journal article 31 Mar 88-30 Sep 90.
||Reprint: Non-Local Closure Model for Vertical Mixing in the Convective Boundary Layer.
||PC A03/MF A01