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Title: Investigating the Linear Dependence of Direct and Indirect Radiative Forcing on Emission of Carbonaceous Aerosols in a Global Climate Model

Abstract

The linearity of dependence of aerosol direct and indirect radiative forcing (DRF and IRF) on emissions is essential to answer the policy-relevant question on how the change in forcing would result from a change in emission. In this study, the forcing-to-emission relationship is investigated for black carbon (BC) and primary organic carbon (OC) emitted from North America and Asia. Direct and indirect radiative forcing of BC and OC are simulated with the Community Atmosphere Model (CAM5.1). Two diagnostics are introduced to aid in policy-relevant discussion: emission-normalized forcing (ENF) and linearity (R). DRF is linearly related to emission for both BC and OC from the two regions and emission-normalized DRF is similar, within 15%. IRF is linear to emissions for weaker sources and regions far from source (North American BC and OC), while for large emission sources and near source regions (Asian OC) the response of forcing to emission is sub-linear. In North America emission-normalized IRF (ENIRF) is 2-4 times higher than that in Asia. The difference among regions and species is primarily caused by failure of accumulation mode particles to become CCN, and then to activate into CDNC. Optimal aggregation area (30ºx 30º) has been used to communicate the regionalmore » variation of forcing-to-emission relationship. For IRF, only 15-40% of the Earth’s surface is significantly affected by the two emission regions, but the forcing in these regions comprises most of the global impact. Linearity of IRF occurs in about two-thirds of the significant regions except for Asian OC. ENF is an effective tool to estimate forcing changes due to reduction of surface emissions, as long as there is sufficient attention to the causes of nonlinearity in the simulations used to derive ENIRF (emission into polluted regions and emission elevation). The differences in ENIRF have important implications for policy decisions. Lower ENIRF in more polluted region like Asia means that reductions of large amounts of OC in these regions would be relatively climate-neutral rather than causing significant warming via IRF reduction.« less

Authors:
ORCiD logo [1]; ORCiD logo [2]; ORCiD logo [2]; ORCiD logo [2]; ORCiD logo [2]; ORCiD logo [1]
  1. Department of Civil and Environmental Engineering, University of Illinois at Urbana-Champaign, Urbana IL USA
  2. Atmospheric Sciences and Global Change Division, Pacific Northwest National Laboratory, Richland WA USA
Publication Date:
Research Org.:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1427897
Report Number(s):
PNNL-SA-126780
Journal ID: ISSN 2169-897X; KP1703020
DOE Contract Number:  
AC05-76RL01830
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Geophysical Research: Atmospheres; Journal Volume: 123; Journal Issue: 3
Country of Publication:
United States
Language:
English

Citation Formats

Chen, Yanju, Wang, Hailong, Singh, Balwinder, Ma, Po-Lun, Rasch, Philip J., and Bond, Tami C. Investigating the Linear Dependence of Direct and Indirect Radiative Forcing on Emission of Carbonaceous Aerosols in a Global Climate Model. United States: N. p., 2018. Web. doi:10.1002/2017JD027244.
Chen, Yanju, Wang, Hailong, Singh, Balwinder, Ma, Po-Lun, Rasch, Philip J., & Bond, Tami C. Investigating the Linear Dependence of Direct and Indirect Radiative Forcing on Emission of Carbonaceous Aerosols in a Global Climate Model. United States. doi:10.1002/2017JD027244.
Chen, Yanju, Wang, Hailong, Singh, Balwinder, Ma, Po-Lun, Rasch, Philip J., and Bond, Tami C. Fri . "Investigating the Linear Dependence of Direct and Indirect Radiative Forcing on Emission of Carbonaceous Aerosols in a Global Climate Model". United States. doi:10.1002/2017JD027244.
@article{osti_1427897,
title = {Investigating the Linear Dependence of Direct and Indirect Radiative Forcing on Emission of Carbonaceous Aerosols in a Global Climate Model},
author = {Chen, Yanju and Wang, Hailong and Singh, Balwinder and Ma, Po-Lun and Rasch, Philip J. and Bond, Tami C.},
abstractNote = {The linearity of dependence of aerosol direct and indirect radiative forcing (DRF and IRF) on emissions is essential to answer the policy-relevant question on how the change in forcing would result from a change in emission. In this study, the forcing-to-emission relationship is investigated for black carbon (BC) and primary organic carbon (OC) emitted from North America and Asia. Direct and indirect radiative forcing of BC and OC are simulated with the Community Atmosphere Model (CAM5.1). Two diagnostics are introduced to aid in policy-relevant discussion: emission-normalized forcing (ENF) and linearity (R). DRF is linearly related to emission for both BC and OC from the two regions and emission-normalized DRF is similar, within 15%. IRF is linear to emissions for weaker sources and regions far from source (North American BC and OC), while for large emission sources and near source regions (Asian OC) the response of forcing to emission is sub-linear. In North America emission-normalized IRF (ENIRF) is 2-4 times higher than that in Asia. The difference among regions and species is primarily caused by failure of accumulation mode particles to become CCN, and then to activate into CDNC. Optimal aggregation area (30ºx 30º) has been used to communicate the regional variation of forcing-to-emission relationship. For IRF, only 15-40% of the Earth’s surface is significantly affected by the two emission regions, but the forcing in these regions comprises most of the global impact. Linearity of IRF occurs in about two-thirds of the significant regions except for Asian OC. ENF is an effective tool to estimate forcing changes due to reduction of surface emissions, as long as there is sufficient attention to the causes of nonlinearity in the simulations used to derive ENIRF (emission into polluted regions and emission elevation). The differences in ENIRF have important implications for policy decisions. Lower ENIRF in more polluted region like Asia means that reductions of large amounts of OC in these regions would be relatively climate-neutral rather than causing significant warming via IRF reduction.},
doi = {10.1002/2017JD027244},
journal = {Journal of Geophysical Research: Atmospheres},
number = 3,
volume = 123,
place = {United States},
year = {Fri Feb 02 00:00:00 EST 2018},
month = {Fri Feb 02 00:00:00 EST 2018}
}