Carbonaceous aerosols in the industrial era

Hansen, James E.; Bond, Tami C.; Cairns, B.; Gaeggler, Heinz; Liepert, Beate G.; Novakov, T.; Schichtel, B. A.

doi:10.1029/2004eo250001

Cited by 22 publications

(13 citation statements)

References 14 publications

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“…Besides CO 2 , methane and soot are potentially the largest global anthropogenic forcings, although estimates of the soot forcing have varied widely [ Ramaswamy et al , 2001; Hansen et al , 2000; Jacobson , 2001; Penner , 2001; Penner et al , 2003]. We define soot as the carbonaceous aerosol product of fossil fuel and biomass burning, including BC and OC, with the distinction between BC and OC made on the basis of optical properties [ Chylek et al , 2003; Hansen et al , 2004].…”

Section: Applicationsmentioning

confidence: 99%

Efficacy of climate forcings

et al. 2005

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[1] We use a global climate model to compare the effectiveness of many climate forcing agents for producing climate change. We find a substantial range in the ''efficacy'' of different forcings, where the efficacy is the global temperature response per unit forcing relative to the response to CO 2 forcing. Anthropogenic CH 4 has efficacy $110%, which increases to $145% when its indirect effects on stratospheric H 2 O and tropospheric O 3 are included, yielding an effective climate forcing of $0.8 W/m 2 for the period 1750-2000 and making CH 4 the largest anthropogenic climate forcing other than CO 2 . Black carbon (BC) aerosols from biomass burning have a calculated efficacy $58%, while fossil fuel BC has an efficacy $78%. Accounting for forcing efficacies and for indirect effects via snow albedo and cloud changes, we find that fossil fuel soot, defined as BC + OC (organic carbon), has a net positive forcing while biomass burning BC + OC has a negative forcing. We show that replacement of the traditional instantaneous and adjusted forcings, Fi and Fa, with an easily computed alternative, Fs, yields a better predictor of climate change, i.e., its efficacies are closer to unity. Fs is inferred from flux and temperature changes in a fixed-ocean model run. There is remarkable congruence in the spatial distribution of climate change, normalized to the same forcing Fs, for most climate forcing agents, suggesting that the global forcing has more relevance to regional climate change than may have been anticipated. Increasing greenhouse gases intensify the Hadley circulation in our model, increasing rainfall in the Intertropical Convergence Zone (ITCZ), Eastern United States, and East Asia, while intensifying dry conditions in the subtropics including the Southwest United States, the Mediterranean region, the Middle East, and an expanding Sahel. These features survive in model simulations that use all estimated forcings for the period 1880-2000. Responses to localized forcings, such as land use change and heavy regional concentrations of BC aerosols, include more specific regional characteristics. We suggest that anthropogenic tropospheric O 3 and the BC snow albedo effect contribute substantially to rapid warming and sea ice loss in the Arctic. As a complement to a priori forcings, such as Fi, Fa, and Fs, we tabulate the a posteriori effective forcing, Fe, which is the product of the forcing and its efficacy. Fe requires calculation of the climate response and introduces greater model dependence, but once it is calculated for a given amount of a forcing agent it provides a good prediction of the response to other forcing amounts.

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Section: Applicationsmentioning

confidence: 99%

Efficacy of climate forcings

et al. 2005

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“…Black carbon (BC) and BC-containing particles form a climatically important category of tropospheric aerosols exerting a direct radiative forcing of climate, inhibiting as well as facilitating cloud formation, and reducing the albedo of ice and snow surfaces, thereby affecting the overall energy budget of the terrestrial climate system [1][2][3][4][5][6][7][8][9][10][11]. They can also limit atmospheric visibility and have a highly negative effect on human health [12].…”

Section: Introductionmentioning

confidence: 99%

T-matrix modeling of linear depolarization by morphologically complex soot and soot-containing aerosols

Mishchenko

Liu

Mackowski

2013

Journal of Quantitative Spectroscopy and Radiative Transfer

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a b s t r a c tWe use state-of-the-art public-domain Fortran codes based on the T-matrix method to calculate orientation and ensemble averaged scattering matrix elements for a variety of morphologically complex black carbon (BC) and BC-containing aerosol particles, with a special emphasis on the linear depolarization ratio (LDR). We explain theoretically the quasi-Rayleigh LDR peak at side-scattering angles typical of low-density soot fractals and conclude that the measurement of this feature enables one to evaluate the compactness state of BC clusters and trace the evolution of low-density fluffy fractals into densely packed aggregates. We show that small backscattering LDRs measured with groundbased, airborne, and spaceborne lidars for fresh smoke generally agree with the values predicted theoretically for fluffy BC fractals and densely packed near-spheroidal BC aggregates. To reproduce higher lidar LDRs observed for aged smoke, one needs alternative particle models such as shape mixtures of BC spheroids or cylinders.Published by Elsevier Ltd.

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“…As a result, there is less penetration of solar energy to the Earth’s surface. It has been suggested [ Jacobson , 2000; Hansen et al , 2004] that the radiative forcing of BC contributes substantially to global warming. In contrast to BC, OC aerosols, like sulfate aerosols, mainly scatter solar radiation.…”

Section: Introductionmentioning

confidence: 99%

Estimate of radiative forcing of Asian biomass‐burning aerosols during the period of TRACE‐P

et al. 2007

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[1] The regional radiative impact of biomass-burning aerosols in Asia is estimated using the new and detailed emission data during the experimental period of Transport and Chemical Evolution over the Pacific (TRACE-P) in March 2001. Integration of the USA National Oceanic and Atmospheric Administration (NOAA) Hybrid Single-Particle 10 Lagrangian Integrated Transport model (HYSPLIT) and a solar radiative transfer model (CLIRAD-SW) allow us to simulate the spatial and temporal distributions of black carbon (BC) and organic carbon (OC) aerosols from biomass burning in the South Asian region. It also allows us to estimate further their aerosol optical properties and radiative forcing. We find that an anticyclone over Bay of Bengal dominates the transport of pollutants of the South Asian region. The monthly mean surface concentration of OC and BC is 1.1 mg m À3 in this region. Western Myanmar has the maximum value, with the concentration reaching 12.5 mg m À3 . The monthly mean clear-sky direct shortwave radiative forcing ranges from À1.9 to 0.4 W m À2 at the top of the atmosphere and from À0.5 to À12.0 W m À2 at surface, resulting in an increase of the atmospheric heating rate from 0.01 to 0.3°C day À1. Owing to the spatial distributions of the aerosol optical depth ratio (OC/BC) and the surface albedo, there is a strong gradient of heating rate near the source regions, which may modify local circulations.

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Carbonaceous aerosols in the industrial era

Cited by 22 publications

References 14 publications

Efficacy of climate forcings

Efficacy of climate forcings

T-matrix modeling of linear depolarization by morphologically complex soot and soot-containing aerosols

Estimate of radiative forcing of Asian biomass‐burning aerosols during the period of TRACE‐P

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