Journal ArticleDOI
Measurement of the effect of Amazon smoke on inhibition of cloud formation.
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Satellite data over the Amazon region during the biomass burning season showed that scattered cumulus cloud cover was reduced from 38% in clean conditions to 0% for heavy smoke, which reverses the regional smoke instantaneous forcing of climate.Abstract:
Urban air pollution and smoke from fires have been modeled to reduce cloud formation by absorbing sunlight, thereby cooling the surface and heating the atmosphere. Satellite data over the Amazon region during the biomass burning season showed that scattered cumulus cloud cover was reduced from 38%in clean conditions to 0%for heavy smoke (optical depth of 1.3). This response to the smoke radiative effect reverses the regional smoke instantaneous forcing of climate from –28 watts per square meter in cloud-free conditions to +8 watts per square meter once the reduction of cloud cover is accounted for.read more
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Journal ArticleDOI
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
Global indirect aerosol effects: a review
Ulrike Lohmann,Johann Feichter +1 more
TL;DR: In this article, the effects of aerosols on the climate system are discussed and different approaches how the climatic implications of these effects can be estimated globally as well as improvements that are needed in global climate models in order to better represent indirect aerosol effects are discussed.
Journal ArticleDOI
Flood or drought: How do aerosols affect precipitation?
Daniel Rosenfeld,Ulrike Lohmann,Graciela B. Raga,Colin D. O'Dowd,Markku Kulmala,Sandro Fuzzi,Anni Reissell,Meinrat O. Andreae +7 more
TL;DR: A conceptual model is proposed that explains this apparent dichotomy of pristine tropical clouds with low CCN concentrations rain out too quickly to mature into long-lived clouds and heavily polluted clouds evaporate much of their water before precipitation can occur.
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
Untangling aerosol effects on clouds and precipitation in a buffered system
Bjorn Stevens,Graham Feingold +1 more
TL;DR: It is proposed that the difficulty in untangling relationships among the aerosol, clouds and precipitation reflects the inadequacy of existing tools and methodologies and a failure to account for processes that buffer cloud and precipitation responses to aerosol perturbations.
References
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Journal ArticleDOI
The NCEP/NCAR 40-Year Reanalysis Project
Eugenia Kalnay,Masao Kanamitsu,Robert Kistler,William D. Collins,D.G. Deaven,L. S. Gandin,M. Iredell,Suranjana Saha,Glenn H. White,John S. Woollen,Yuejian Zhu,Muthuvel Chelliah,Wesley Ebisuzaki,Wayne Higgins,John E. Janowiak,Kingtse C. Mo,Chester F. Ropelewski,Julian X. L. Wang,Ants Leetmaa,Richard W. Reynolds,Roy L. Jenne,Dennis Joseph +21 more
TL;DR: The NCEP/NCAR 40-yr reanalysis uses a frozen state-of-the-art global data assimilation system and a database as complete as possible, except that the horizontal resolution is T62 (about 210 km) as discussed by the authors.
Journal ArticleDOI
Climate change 2001: the scientific basis
John Theodore Houghton,Y. Ding,David John Griggs,M. Noguer,P. J. van der Linden,X. Dai,K. Maskell,C. A. Johnson +7 more
TL;DR: In this article, the authors present an overview of the climate system and its dynamics, including observed climate variability and change, the carbon cycle, atmospheric chemistry and greenhouse gases, and their direct and indirect effects.
Journal ArticleDOI
Aerosols, cloud microphysics, and fractional cloudiness.
TL;DR: Increases in aerosol concentrations over the oceans may increase the amount of low-level cloudiness through a reduction in drizzle—a process that regulates the liquid-water content and the energetics of shallow marine clouds—to contribute to a cooling of the earth's surface.
Journal ArticleDOI
Aerosols, climate, and the hydrological cycle
TL;DR: Human activities are releasing tiny particles (aerosols) into the atmosphere that enhance scattering and absorption of solar radiation, which can lead to a weaker hydrological cycle, which connects directly to availability and quality of fresh water, a major environmental issue of the 21st century.
Journal ArticleDOI
The Influence of Pollution on the Shortwave Albedo of Clouds
TL;DR: In this article, it was shown that pollution can increase the reflectance (albedo) of clouds; by increasing the absorption coefficient it acts to decrease the reflectances, and that the former effect (brightening of the clouds in reflection, hence climatically a cooling effect) dominates for thin to moderately thick clouds.