2013 Progress Report: Investigating the Effects Of Atmospheric Aging on the Radiative Properties and Climate Impacts of Black Carbon Aerosol

EPA Grant Number: R835033
Title: Investigating the Effects Of Atmospheric Aging on the Radiative Properties and Climate Impacts of Black Carbon Aerosol
Investigators: Kroll, Jesse H. , Davidovits, Paul , Heald, Colette L.
Institution: Massachusetts Institute of Technology , Boston College
EPA Project Officer: Hunt, Sherri
Project Period: May 1, 2012 through April 30, 2015 (Extended to April 30, 2016)
Project Period Covered by this Report: May 1, 2013 through April 30,2014
Project Amount: $899,654
RFA: Black Carbon's Role In Global To Local Scale Climate And Air Quality (2010) RFA Text |  Recipients Lists
Research Category: Global Climate Change , Climate Change , Air

Objective:

Black carbon (BC) particles play a significant role in climate forcing, yet the effects of aging – atmospheric processes that affect the mass, size, shape, and chemical composition of aerosol particles – on their radiative properties are poorly constrained. This combined laboratory and modeling study will provide new insights into the detailed effects of atmospheric aging on the climate impacts of black carbon particles.

Progress Summary:

In Year 2 of this project we continued our work on BC heterogeneous aging, examining in detail the kinetics of such processes, plus the changes to chemical composition and water-uptake properties of the particles upon aging. Results indicate that heterogeneous oxidation is a rapid enough process to compete with other aging mechanisms (condensation, coagulation), but also that changes to water-uptake properties are likely dominated by condensation processes. We have also carried out the first study of the aging of BrC particles, finding that their chemical composition changes dramatically after the equivalent of a few days of oxidation, and more importantly that oxidation appears to degrade their light-absorbing properties. Additional experimental work has focused on measurements of the mass spectra and morphologies of BCcontaining particles from various sources. Modeling work has focused on improving the simulation of BC in a global model (GEOS-Chem) and developing an accompanying simulation of BrC. We updated the properties and aging mechanism for BC particles in the model and found that the short BC lifetime is critical to capturing more remote measurements. Our estimate of the direct radiative forcing of BC is considerably lower that the most recent estimate from the IPCC. We attribute this difference to previous overestimates of the BC lifetime as well as a misattribution of BrC absorption to BC.

Future Activities:

In Year 3 of this project, laboratory experiments will focus on measurements of changes to optical properties of BC (and BrC) upon oxidative and condensational aging, and parameterization of these changes for use in global models. Future modeling work will include efforts to further develop our simulation of BrC based on observational constraints, as well as further investigation of the impacts of aging, as represented by the laboratory experiments, on the global burden and forcing from BC.


Journal Articles on this Report : 2 Displayed | Download in RIS Format

Other project views: All 25 publications 9 publications in selected types All 9 journal articles
Type Citation Project Document Sources
Journal Article Heald CL, Ridley DA, Kroll JH, Barrett SRH, Cady-Pereira KE, Alvarado MJ, Holmes CD. Contrasting the direct radiative effect and direct radiative forcing of aerosols. Atmospheric Chemistry and Physics 2014;14(11):5513-5527. R835033 (2013)
R835033 (2014)
R835033 (Final)
  • Full-text: ACP-Full Text PDF
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  • Abstract: ACP-Abstract
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  • Other: ResearchGate-Full Text PDF
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  • Journal Article Lambe AT, Cappa CD, Massoli P, Onasch TB, Forestieri SD, Martin AT, Cummings MJ, Croasdale DR, Brune WH, Worsnop DR, Davidovits P. Relationship between oxidation level and optical properties of secondary organic aerosol. Environmental Science & Technology 2013;47(12):6349-6357. R835033 (2012)
    R835033 (2013)
    R835033 (2014)
    R835033 (Final)
  • Abstract from PubMed
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  • Abstract: ES&T-Abstract
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  • Supplemental Keywords:

    black carbon, aerosol, light-absorbing carbon, brown carbon, direct radiative effects, climate, global modeling, optical properties, atmospheric aging

    Progress and Final Reports:

    Original Abstract
    2012 Progress Report
    2014 Progress Report
    Final Report