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J. M. Wilczak, W. F. Dabberdt, and R. A. Kropfli

~ement with the observations. Model simulationsindicate that sea-/land-roughness differences and planetary vorticity are of minor importance in forming themidchannel eddy (MCE), an eddy that is observed in the channel during the early morning hours. MCEformation is, however, shown to be stron~y dependent on the initial stratification of the atmosphere, with moreintense eddies forming as the stability increases. A second independent mechanism for MCE formation appearsto be the inleraction of drainage flows

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Matthias Drusch

1. Introduction Sea ice concentration (CI) is a key parameter in the exchange processes between the ocean and the atmosphere. It strongly influences albedo, surface fluxes of latent and sensible heat, and the surface wind drag. The exchange processes between ice-covered ocean surfaces and the atmosphere have been studied on various spatial and temporal scales covering decadal modes (e.g., Hurrell et al. 2003 ; Deser et al. 2002 ), annual and seasonal variability (e.g., Deser et al. 2000

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Jean-Pierre Pinty, Patrick Mascart, Evelyne Richard, and Robert Rosset

(Manuscript received 31 October 1988, in final form 24 February 1989) Many recent studies have suggested that heterogeneities in soil properties or vegetation characteristics maytrigger mesoscale circulations in the planetary boundary layer (PBL). Unfortunn~ely, theso flows appear to bevery sensitive to the choice of the model characteristic~ and therefore require a careful calibmtlon of the param.eterization r~senting the vegetation/atmosphere interface, In this paper, the micromcteorological data

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Walter A. Lyons, Rebecca H. Calby, and Cecil S. Keen

relationship between visibilityand sulfate aerosol mass concentrations, it is speculated that approximately 30 X l0s kg of soifate were removedfrom the planetary boundary layer (PBL). The removal was not due solely to wet deposition. Rather, considerationof thunderstorm dynamics suggests that perhaps two-thirds of the removal from the PBL could have been dueto convective displacement into the free atmosphere, perhaps to altitudes as high as the tropopanse.1. Introduction Large-scale persistent elevated

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D. M. Leahey, M. C. Hansen, and M. B. Schroeder

only near the ground, but also withinthe capping inversion surmounting the convectivelyactive planetary boundary layer (PBL) (Hooke andJones 1986). A wide variety of dynamic phenomenaare causes of gravity wave excitation. These includewind shear, thunderstorm activity, and frontal passages(Finnigan et al. 1984; Stull 1976; Egger et al. 1993;Haase 1991 ). Mountain lee waves are also manifestations of gravity wave phenomena. They will tend tooccur in the upper atmosphere at discontinuities in

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Jonathan E. Pleim and Aijun Xiu

verticalturbulent transport of heat, moisture, and momentum,a flux-profile algorithm that couples the surface withthe atmosphere through the surface fluxes, and a simplesurface radiation model. The land surface portion ofthe model is based on a model developed by Noilhanand Planton ( 1989). The PBL module and flux-profilerelationships are the same as currently used in the latestversion of RADM. The PBL model is a hybrid of non-local closure, for convective conditions, and eddy dif-fusion. A preliminary version

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J. A. Coakley Jr. and G. W. Grams

developed to assess the impact of stratospheric aerosolson the global climate through their effect on the equilibrium global mean surface temperature. With theassumptions that the radiation in the atmosphere can be treated as diffuse radiation and that the effect ofthe gases in the stratosphere can be approximated by equivalent gray absorbers and scatterers, an analyticexpression which depends only on the optical properties of the aerosol and the planetary albedo is derivedfor the fractional change in

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Cor M. J. Jacobs and Henk A. R. de Bruin

decreasing stomatal aperture. The individual stomatal resistances in a canopy can be integrated to yield the surface resistance r s . Because the flow in the planetary boundary layer (PBL) is almost always turbulent, the exchange of water vapor between vegetation and the atmosphere is controlled to a large extent by r s . Thus, changes in λE of canopies are often closely linked with changes in r s . However, such changes in λE are modified by the interaction between the atmosphere and the

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S. Argentini, P. J. Wetzel, and V. M. Karyampudi

land surface properties on mesoseale atmospheric phenomena,it is important to include physically realistic pararaeterizations of major biophysical processes involved. Theprimary influence of the surface on the atmosphere occurs via its control of the surface energy budget and theconsequent turbulent exchange with the planetary boundary layer (PBL). The physical pararaeteriza~ion of thecomplex surface processes may not be confidently incorporated into a three-dimensional model without

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Michael T. Kiefer, Warren E. Heilman, Shiyuan Zhong, Joseph J. Charney, and Xindi Bian

1. Introduction The role of the heat output from a wildland fire in perturbing the atmosphere has been examined to varying degrees with numerical models for approximately 20 years. To date, examination of the atmospheric response to the heat output from wildland fires by the fire weather research community has largely focused on higher-intensity fires [mean parameterized vertical heat fluxes O (15–100+ kW m −2 )] (e.g., Heilman and Fast 1992 ; Cunningham et al. 2005 ; R. Sun et al. 2006

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