Measurements of the concentration and composition of nuclei for cirrus formation
Paul J. DeMott,Daniel J. Cziczo,Anthony J. Prenni,D. M. Murphy,Sonia M. Kreidenweis,David S. Thomson,Randolph D. Borys,D. C. Rogers +7 more
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Simultaneous measurements of the concentration and composition of tropospheric aerosol particles capable of initiating ice in cold (cirrus) clouds are reported, suggesting a predominant potential impact of these nuclei on cirrus formed by slow, large-scale lifting or small cooling rates, including subvisual cirrus.Abstract:
This article addresses the need for new data on indirect effects of natural and anthropogenic aerosol particles on atmospheric ice clouds. Simultaneous measurements of the concentration and composition of tropospheric aerosol particles capable of initiating ice in cold (cirrus) clouds are reported. Measurements support that cirrus formation occurs both by heterogeneous nucleation by insoluble particles and homogeneous (spontaneous) freezing of particles containing solutions. Heterogeneous ice nuclei concentrations in the cirrus regime depend on temperature, relative humidity, and the concentrations and physical and chemical properties of aerosol particles. The cirrus-active concentrations of heterogeneous nuclei measured in November over the western U.S. were <0.03 cm–3. Considering previous modeling studies, this result suggests a predominant potential impact of these nuclei on cirrus formed by slow, large-scale lifting or small cooling rates, including subvisual cirrus. The most common heterogeneous ice nuclei were identified as relatively pure mineral dusts and metallic particles, some of which may have origin through anthropogenic processes. Homogeneous freezing of large numbers of particles was detected above a critical relative humidity along with a simultaneous transition in nuclei composition toward that of the sulfate-dominated total aerosol population. The temperature and humidity conditions of the homogeneous nucleation transition were reasonably consistent with expectations based on previous theoretical and laboratory studies but were highly variable. The strong presence of certain organic pollutants was particularly noted to be associated with impedance of homogeneous freezing.read more
Citations
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Bounding the role of black carbon in the climate system: A scientific assessment
Tami C. Bond,Sarah J. Doherty,David W. Fahey,Piers M. Forster,Terje Koren Berntsen,Benjamin DeAngelo,Mark Flanner,Steven J. Ghan,Bernd Kärcher,Dorothy Koch,Stefan Kinne,Yutaka Kondo,Patricia K. Quinn,Marcus C. Sarofim,Martin G. Schultz,Michael Schulz,Chandra Venkataraman,Hua Zhang,Shiqiu Zhang,Nicolas Bellouin,Sarath K. Guttikunda,Philip K. Hopke,Mark Z. Jacobson,Johannes W. Kaiser,Zbigniew Klimont,Ulrike Lohmann,Joshua P. Schwarz,Drew Shindell,Trude Storelvmo,Stephen G. Warren,Charles S. Zender +30 more
TL;DR: In this paper, the authors provided an assessment of black-carbon climate forcing that is comprehensive in its inclusion of all known and relevant processes and that is quantitative in providing best estimates and uncertainties of the main forcing terms: direct solar absorption; influence on liquid, mixed phase, and ice clouds; and deposition on snow and ice.
Journal ArticleDOI
The formation, properties and impact of secondary organic aerosol: current and emerging issues
Mattias Hallquist,John C. Wenger,Urs Baltensperger,Yinon Rudich,David Simpson,David Simpson,Magda Claeys,J. Dommen,Neil M. Donahue,Christian George,Christian George,Allen H. Goldstein,Jacqueline F. Hamilton,Hartmut Herrmann,Thorsten Hoffmann,Yoshiteru Iinuma,Myoseon Jang,Michael E. Jenkin,Jose L. Jimenez,Astrid Kiendler-Scharr,Willy Maenhaut,Gordon McFiggans,Th. F. Mentel,Anne Monod,André S. H. Prévôt,John H. Seinfeld,Jason D. Surratt,Rafal Szmigielski,Jürgen Wildt +28 more
TL;DR: In this article, an overview of the atmospheric degradation mechanisms for SOA precursors, gas-particle partitioning theory and analytical techniques used to determine the chemical composition of SOA is presented.
Journal ArticleDOI
Aerosol cloud precipitation interactions. Part 1. The nature and sources of cloud-active aerosols
TL;DR: In this article, the authors discuss the role of chemical composition and particle size in cloud condensation nucleation processes, and the role that the chemical composition plays in the process of cloud droplet and ice nucleation.
Journal ArticleDOI
Review of the vapour pressures of ice and supercooled water for atmospheric applications
DM Murphy,Thomas Koop +1 more
TL;DR: In this paper, the vapour pressure of ice and supercooled water is reviewed with an emphasis on atmospheric applications, and various parametrizations are given for the vapor pressure, molar heat capacity, and latent heat of both ice and liquid water.
Journal ArticleDOI
Predicting global atmospheric ice nuclei distributions and their impacts on climate
Paul J. DeMott,Anthony J. Prenni,Xiaohong Liu,Sonia M. Kreidenweis,Markus D. Petters,Cynthia H. Twohy,Mathews S. Richardson,Trude Eidhammer,D. C. Rogers +8 more
TL;DR: It is shown that the concentrations of ice nuclei active in mixed-phase cloud conditions can be related to temperature and the number concentrations of particles larger than 0.5 μm in diameter, which reduces unexplained variability in iceuclei concentrations at a given temperature from ∼103 to less than a factor of 10.
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