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Lulin Xue, Amit Teller, Roy Rasmussen, Istvan Geresdi, Zaitao Pan, and Xiaodong Liu

. More recently, Saleeby and Cotton (2008) and Lin and Colle (2011) applied different size-dependent riming approaches to orographic cloud simulations. Their results showed that significant improvements of snowfall prediction over mountainous areas have been achieved compared to size-independent riming approach. Muhlbauer et al. (2010) investigated the anthropogenic aerosol effects on mixed-phase orographic clouds by simulating an ideal two-dimensional bell-shaped case with three dynamic

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P. B. Russell, J. Redemann, B. Schmid, R. W. Bergstrom, J. M. Livingston, D. M. McIntosh, S. A. Ramirez, S. Hartley, P. V. Hobbs, P. K. Quinn, C. M. Carrico, M. J. Rood, E. Öström, K. J. Noone, W. von Hoyningen-Huene, and L. Remer

1. Introduction Aerosol single scattering albedo (SSA) ω (the fraction of intercepted light that is scattered, rather than absorbed) is important in determining aerosol climatic effects (e.g., Hansen et al. 1998 ; Haywood and Shine 1995 ; Chylek and Wong 1995 ), explaining differences between calculated and measured downwelling radiative fluxes (e.g., Halthore et al. 1998 ; Kato et al. 1997 ; Mlawer et al. 2000 ), and determining the relationship between satellite-measured radiance and

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Hongfei Shao and Guosheng Liu

is typically parameterized as a function of N a with constant coefficients, e.g., N c = σN a α ( Boucher and Lohmann 1995 ; Jones and Slingo 1996 ; Lohmann and Feichter 1997 ; Kiehl et al. 2000 ; Menon et al. 2002 ; Rotstayn and Liu 2003 ). Because σ is also a determinant of aerosol activation and may change simultaneously when anthropogenic aerosols are added to the natural aerosol background, by letting σ being a constant, it is implicitly assumed that all effects on N c due

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Lynn M. Russell, Kevin J. Noone, Ronald J. Ferek, Robert A. Pockalny, Richard C. Flagan, and John H. Seinfeld

measurements of the CCN properties of combustion-derived carbonaceous aerosols to allow one to predict reliably the effect of such aerosols on cloud droplet activation. Ship tracks provide an ideal mechanism for studying effects of anthropogenic emissions on marine stratocumulus clouds. The present work provides an initial investigation of the fate of organic aerosols emitted from ship exhaust in the marine stratocumulus layer. A major question is, to what extent can the microphysical features of ship

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Hong-Hai Zhang, Gui-Peng Yang, Chun-Ying Liu, and Lu-Ping Su

constituent of the marine atmospheric aerosols, mainly including sea salts, mineral aerosols, and secondary aerosols [non–sea salt sulfate (nss- ), , and ], which mainly come from the chemical conversions of anthropogenic SO 2 , nitrogen oxide (NO x ), and NH 3 from the continent. Over the coastal and shelf areas influenced by human activities, nss- is the major contributor of condensation nuclei (CN), accounting for over 90% of the total particle numbers ( Fitzgerald 1991 ) and eventually cloud

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Olivier Boucher

β ( Fig. 3f ) is generally better because there is a cancellation of the effects at low and high solar zenith angles. If some absorption is added ( Figs. 4a,c,e ), no improvement is observed in the prediction of upscatter fractions by the HG phase function for accumulation mode particles. There is, however, a tendency to a betterprediction of upscatter fractions for coarse-mode size distributions when a significant amount of absorption is considered. Moreover, the transition between under- and

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Steven J. Ghan, Gina Guzman, and Hayder Abdul-Razzak

, 1995: The sulfate-CCN-cloud albedo effect. Tellus, 47B, 281–300. Charlson, R. J., S. E. Schwartz, J. M. Hales, R. D. Cess, J. A. Coakley Jr., J. E. Hansen, and D. J. Hoffman, 1992: Climate forcing by anthropogenic aerosols. Science, 255, 423–430. Chuang, C. C., J. E. Penner, K. E. Taylor, A. S. Grossman, and J. J. Walton, 1997: An assessment of the radiative effects of anthropogenic sulfate. J. Geophys. Res., 102, 3761–3778. Ghan, S. J., L. R. Leung, R. C. Easter, and H. Abdul

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Sarah D. Brooks, Tim D. Jickells, Peter S. Liss, Daniel C. O. Thornton, and Renyi Zhang

transported from the continents have been shown to impact tropical cyclones, by modifying radiative budget and microphysical processes ( Wang et al. 2014c ). The coupled microphysical and radiative effects of anthropogenic aerosols result in delayed development, weakened intensity, and early dissipation of tropical cyclones, but an enlarged rainband and increased precipitation under polluted conditions ( Wang et al. 2014c ). Another recent observational analysis has shown enlarged rainfall areas of

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U. Lohmann and K. Diehl

, the insufficient knowledge of ice multiplication processes and the uncertainty related to the scarcity of heterogeneous freezing data for mixed-phase clouds. Therefore the results described below are only sensitivity studies, discussing a few of the many possible scenarios. The question here is whether the total anthropogenic indirect aerosol effect on the net radiation at TOA, that is, the total of all aerosol effects on warm, mixed-phase and ice clouds (from here on just termed indirect aerosol

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Judith L. Lean

anthropogenic ozone change. Increased concentrations of GHGs may accelerate or decelerate ozone changes in different geographical regions and at different altitudes in Earth’s atmosphere (e.g., Rind et al. 1998 ; Waugh et al. 2009 ; Eyring et al. 2010 ). Increased GHGs in the upper stratosphere enhance radiative cooling to space, which increases ozone by, for example, slowing the catalytic chemical destruction cycles that involve ODSs. Increased concentrations of methane and nitrous oxide also affect

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