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Amy Solomon and Peter H. Stone

1. Introduction Cehelsky and Tung (1991) and Welch and Tung (1998) used a two-layer quasigeostrophic β -plane model to study the dynamical processes by which the midlatitude atmosphere equilibrates. They found that if the forcing is strong enough, the initially most unstable wave will saturate causing longer less unstable waves to dominate the heat transport in the equilibrated state. They also found that the equilibrated state of their model was linearly stable to the dominant heat

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R. L. Miller and I. Tegen

1. Introduction Radiative forcing by anthropogenic aerosols exceeds the forcing by anthropogenic CO 2 in certain regions and may obscure the climate “fingerprint” attributed to the latter ( Mitchell et al. 1995 ). Industrial sulfate aerosols have received much attention, but soil dust, being more abundant, has a greater radiative effect in certain regions ( Li et al. 1996 ) and a comparable effect globally ( Sokolik and Toon 1996 ; Tegen et al. 1997 ). Soil dust aerosols are created by the

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Guo-Xiong Wu

based on alinear system is shown to give an inadequate de-~'iption of the balance of angular momentum. The responseof the atmosphere to mechanical forcing in a nonlinear framework is then discus~l, using a two-level quasigeostrophic long-wave spectral model based on spherical coordinates, including diabatic heating, surfacefriction and mountains. The nonlinear theory shows that there exists a critical mountain height He which isa function of the frictional coet~icient as well as the phase difference

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H. L. Tanaka

Atlantic sectors, while the terminology of the annular mode is reserved essentially for the zonally symmetric variation in the atmosphere. The AO is successfully simulated by a number of realistic general circulation models with fixed forcing ( Feldstein and Lee 1998 ; Yamazaki and Shinya 1999 ; Fyfe et al. 1999 ; Shindell et al. 1999 ; Limpasuvan and Hartmann 1999 , 2000 ; Boer et al. 2001 ; Robertson 2001 ). The basic features of the zonally symmetric structures are also simulated using simple

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Jorgen S. Frederiksen

determining spectra of transient vorticity variance. However, they say little or nothing about the effect of the mean (single realization) topography of the ocean or atmosphere on the structures of the mean flows or about the problem of parameterizing the effects of the interaction of subgrid-scale turbulent eddies with the mean topography. In the special case of unforced and inviscid flow (or flow for which the forcing and viscosity satisfy special balance conditions), it is possible to study

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Rajul E. Pandya, Dale R. Durran, and Morris L. Weisman

a variety of simplified models. Several investigators have considered the linear response of a stably stratified resting fluid to a specified heat source (e.g., Smith and Lin 1982 ; Lin and Smith 1986 ; Nicholls et al. 1991 ; Mapes 1993 ; Pandya et al. 1993 ). In the subset of these studies that are particularly relevant to deep convection, Nicholls et al. (1991) and Mapes (1993) considered a thermal forcing with a vertical profile that resembled that of observed mesoscale convective

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Guoxing Chen, Wei-Chyung Wang, and Jen-Ping Chen

consistent with the biases found in the smaller simulated shortwave cloud radiative forcing in these regions ( Calisto et al. 2014 ; Flato et al. 2014 ). It is also known that these regions have been affected by aerosols emitted from the continents. For instance, the southeast Pacific (SEP), where the largest and most persistent stratocumulus deck in the world resides, is exposed to anthropogenic aerosols produced by copper smelters in South America ( Huneeus et al. 2006 ). The increased aerosols not

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Clark J. Weaver, Paul Ginoux, N. Christina Hsu, Ming-Dah Chou, and Joanna Joiner

1. Introduction On a local scale mineral aerosol (dust) can significantly impact the atmospheric radiation budget ( Carlson and Benjamin 1980 ; d'Almeida 1987 ; Li et al. 1996 ) but determining the magnitude of forcing on a global scale is uncertain. This is due to limited information on the global spatial distribution of dust and uncertainties in the optical parameters of the dust. Currently, the only approach to obtaining the dust size and spatial distributions on a global scale is

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Joowan Kim, William J. Randel, Thomas Birner, and Marta Abalos

circulation, which comprises ascent in the tropics and poleward and descending motion in the midlatitude and polar region [known as the Brewer–Dobson circulation (BDC); Brewer et al. 1949 ; Dobson 1956 ]. Recent work has highlighted that the BDC is composed of two branches: a deep branch driven by wave forcing in the deep stratosphere and a shallow branch driven by wave forcing in the subtropical and midlatitude lower stratosphere ( Plumb 2002 ; Birner and Bönisch 2011 ). The deep branch is largely

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Joseph Egger and Klaus-Peter Hoinka

1. Introduction Zonal mean momentum budgets have been long considered in order to better understand the structure and intensity of the zonal mean flow (e.g., Oort and Peixoto 1983 ). The contribution of the “waves” to the budgets—that is, by the deviations from the mean state—is of key interest. The so-called Eliassen–Palm (EP) flux played a dominating role in this context because its divergence “is a direct measure of the total forcing of the zonal mean state by the eddies” ( Edmon et al

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