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Peter J. Marinescu, Susan C. van den Heever, Max Heikenfeld, Andrew I. Barrett, Christian Barthlott, Corinna Hoose, Jiwen Fan, Ann M. Fridlind, Toshi Matsui, Annette K. Miltenberger, Philip Stier, Benoit Vie, Bethan A. White, and Yuwei Zhang

also vary, particularly in CCN-limited regimes (e.g., Reutter et al. 2009 ), which then may have many subsequent feedbacks on a cloud’s characteristics and evolution (e.g., Twomey 1977 ; Albrecht 1989 ). Typically, the majority of CCN are ingested through the bases of deep convective clouds within the atmospheric boundary layer, although several studies have shown that some fraction of CCN in the middle troposphere can also become entrained within deep convective updrafts, form cloud droplets

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Jianjun Liu, Zhanqing Li, and Maureen Cribb

indirect effect; Albrecht 1989 ). AIE are the dominant contributors to the overall aerosol radiative forcing in most climate models yet are poorly constrained and can vary by a factor of 5 across different models ( Quaas et al. 2009 ; Wood et al. 2015 ). Marine boundary layer (MBL) clouds are common over the subtropical and midlatitude oceans and are particularly susceptible to perturbations in aerosols ( Wood et al. 2015 ). These clouds strongly influence regional and global climate systems

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Stacey Kawecki, Geoffrey M. Henebry, and Allison L. Steiner

Shepherd (2005) , including 1) an increase in low-level convergence and convection from the higher surface roughness of urban areas; 2) a destabilization of the boundary layer from the urban heat island (UHI) effect, which can trigger localized circulations or UHI-generated convective clouds, and 3) higher aerosol concentrations over urban areas that increase the number of CCN and lifetime of clouds. Urban aerosol concentrations are typically higher than background aerosol concentrations because of

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Jiwen Fan, Yuan Wang, Daniel Rosenfeld, and Xiaohong Liu

. Realizing it is hard to revisit all of the important points laid out throughout the paper, below we only summarize some key points in each aspect. For warm boundary layer clouds, we have known that ACI is a lot more complicated than the Twomey effect and precipitation suppression due to reduced droplet size. Warm-cloud invigoration with increased liquid water content, taller clouds, and more precipitation could occur when adding aerosols to clouds with very low droplet number concentration. The current

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Yan Yang, Jiwen Fan, L. Ruby Leung, Chun Zhao, Zhanqing Li, and Daniel Rosenfeld

. 2007 ; Yang and Gong 2010 ; Yang et al. 2013a , b ). The long-term reduction trend has been attributed to anthropogenic aerosols upwind of the mountains that suppress rain by reducing droplet size that leads to less efficient conversion of droplets to raindrops (e.g., Givati and Rosenfeld 2004 ; Rosenfeld et al. 2007 ; Zubler et al. 2011 ). Aerosols can alter clouds and precipitation through both aerosol–radiation interaction (ARI) and aerosol–cloud interaction (ACI), which currently

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Yun Lin, Yuan Wang, Bowen Pan, Jiaxi Hu, Yangang Liu, and Renyi Zhang

climate ( IPCC 2013 ). Although the previous studies have examined the aerosol effects on isolated continental DCCs ( Fan et al. 2007a , 2008 ; Li et al. 2008b ), the continental cloud system consisting of various boundary layer cloud regions has not been properly represented in current atmospheric models because of poorly parameterized small-scale turbulence and convection ( Zhang et al. 2005 ; Vogelmann et al. 2012 ; Wood 2012 ). To evaluate the properties of such continental boundary layer

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Nicholas R. Nalli, William L. Smith, and Quanhua Liu

approximate more nebulous Sc, Ci, and altocumulus (Ac) cloud forms lacking flat boundaries, 4, 5, 8; 3–5, 7–9; or 1, 2, 9 [e.g., WMO (1956) , p. 40, 47, and 53]. For simplicity, in the current work we assume clouds close enough to the surface to disregard Earth curvature (as would be the case for most opaque water-droplet clouds and certainly FWC); the observer is assumed to be near zenith, and both the sun and observer are considered far enough away such that rays may be assumed parallel. Figure

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Baolin Jiang, Bo Huang, Wenshi Lin, and Suishan Xu

present, second- to sixth-order advection schemes are available for both vertical and horizontal directions. The available lateral boundary conditions include periodic, open symmetric, and specified options, while the bottom boundary conditions contain physical and free-slip options. Currently, cloud microphysics, cumulus parameterization, surface physics, planetary boundary layer physics, and atmospheric radiation physics are included in the model physics component. A variety of coupled physical and

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Yvonne Boose, Zamin A. Kanji, Monika Kohn, Berko Sierau, Assaf Zipori, Ian Crawford, Gary Lloyd, Nicolas Bukowiecki, Erik Herrmann, Piotr Kupiszewski, Martin Steinbacher, and Ulrike Lohmann

is part of the automatic monitoring network of MeteoSwiss (SwissMetNet). A wide range of aerosol properties, trace gases, and meteorological parameters are continuously recorded by the Paul Scherrer Institute ( Bukowiecki et al. 2016 ), Empa ( Steinbacher et al. 2015 ), and MeteoSwiss ( Appenzeller et al. 2008 ), respectively. The aerosol pattern at the observatory follows a yearly cycle. High particle concentrations are found in summer because of the elevation of the planetary boundary layer

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Christina S. McCluskey, Thomas C. J. Hill, Francesca Malfatti, Camille M. Sultana, Christopher Lee, Mitchell V. Santander, Charlotte M. Beall, Kathryn A. Moore, Gavin C. Cornwell, Douglas B. Collins, Kimberly A. Prather, Thilina Jayarathne, Elizabeth A. Stone, Farooq Azam, Sonia M. Kreidenweis, and Paul J. DeMott

both methods produce similar aerosol size distributions ( Prather et al. 2013 ) and size-resolved chemical mixing states ( Collins et al. 2014 ). DeMott et al. (2015) have reported that INP number concentrations measured from these laboratory systems are generally similar to those observed in the ambient marine boundary layer when consideration is given to total particle emissions in the size range expected for SSA (i.e., ambient cases that did not include obvious pollution of nucleation

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