3 years ago

Investigating the linear dependence of direct and indirect radiative forcing on emission of carbonaceous aerosols in a global climate model

Tami C. Bond, Po-Lun Ma, Hailong Wang, Balwinder Singh, Philip J. Rasch, Yanju Chen
The relationship between forcing and emission is investigated for black carbon (BC) and primary organic carbon (OC) emitted from North America and Asia. Direct and indirect radiative forcing (DRF and IRF) of BC and OC are simulated with CAM5.1. Two diagnostics are introduced to aid policy-relevant discussions: linearity and emission-normalized forcing. DRF is linearly related to emission for both BC and OC from two regions and the linear relationship is similar, within 15%. IRF is linear in emissions when emissions are lower and regions far from sources (North American BC and OC). Indirect radiative forcing is sub-linear for strong sources and near-source regions (Asian OC). Emission-normalized IRF in North America is 2-4 times higher than that in Asia. The difference among regions and species is primarily caused by particle density as high density of BC results in fewer emitted particles, and by the processes for accumulation mode particles to become CCN and then to activate into cloud droplet . Lower emission-normalized IRF in more polluted regions means that reductions of OC in these regions would be relatively climate-neutral rather than causing significant warming via IRF reduction. An optimal aggregation area (30° x 30°) is identified for analysis of the forcing-to-emission relationship. For IRF, only 15-40% of the Earth's surface is significantly affected by an emission region, but forcing in these regions comprises most of the global impact. Emission-normalized forcing can be used to estimate forcing changes due to emission reductions, as long as causes of nonlinearity are identified and considered.

Publisher URL: http://onlinelibrary.wiley.com/resolve/doi

DOI: 10.1002/2017JD027244

You might also like
Discover & Discuss Important Research

Keeping up-to-date with research can feel impossible, with papers being published faster than you'll ever be able to read them. That's where Researcher comes in: we're simplifying discovery and making important discussions happen. With over 19,000 sources, including peer-reviewed journals, preprints, blogs, universities, podcasts and Live events across 10 research areas, you'll never miss what's important to you. It's like social media, but better. Oh, and we should mention - it's free.

  • Download from Google Play
  • Download from App Store
  • Download from AppInChina

Researcher displays publicly available abstracts and doesn’t host any full article content. If the content is open access, we will direct clicks from the abstracts to the publisher website and display the PDF copy on our platform. Clicks to view the full text will be directed to the publisher website, where only users with subscriptions or access through their institution are able to view the full article.