Published October 13, 2017 | Version v1
Journal article Open

Aerosols at the poles: an AeroCom Phase II multi-model evaluation

Authors/Creators

  • 1. Center for International Climate and Environmental Research – Oslo (CICERO), Oslo, Norway
  • 2. NASA Goddard Institute for Space Studies and Columbia Earth Institute, New York, NY, USA
  • 3. Laboratoire des Sciences du Climat et de l'Environnement, CEA-CNRS-UVSQ, Gif-sur-Yvette, France
  • 4. Department of Meteorology, University of Reading, Reading, UK
  • 5. Department of Geosciences, University of Oslo, Oslo, Norway
  • 6. Earth System Science Interdisciplinary Center, University of Maryland, College Park, MD, USA
  • 7. NASA Goddard Space Flight Center, Greenbelt, MD, USA
  • 8. Directorate for Sustainable Resources, Joint Research Centre, European Commission, Ispra, Italy
  • 9. Pacific Northwest National Laboratory, Richland, WA, USA
  • 10. Norwegian Meteorological Institute, Oslo, Norway
  • 11. National Center for Atmospheric Research, Boulder, CO, USA
  • 12. Department of Atmospheric Science, University of Wyoming, USA
  • 13. Atmospheric Sciences Research Center, State University of New York at Albany, New York, USA
  • 14. Royal Netherlands Meteorological Institute, De Bilt, the Netherlands
  • 15. Climate and Space Sciences and Engineering, University of Michigan, Ann Arbor, MI, USA
  • 16. Department of Physics, University of Oxford, Oxford, UK
  • 17. Research Institute for Applied Mechanics, Kyushu University, Fukuoka, Japan
  • 18. Max Planck Institute for Meteorology, Hamburg, Germany
  • 19. Laboratory for Climate Studies, National Climate Center, China Meteorological Administration, Beijing, China

Description

Atmospheric aerosols from anthropogenic and natural sources reach the polar regions through long-range transport and affect the local radiation balance. Such transport is, however, poorly constrained in present-day global climate models, and few multi-model evaluations of polar anthropogenic aerosol radiative forcing exist. Here we compare the aerosol optical depth (AOD) at 550 nm from simulations with 16 global aerosol models from the AeroCom Phase II model intercomparison project with available observations at both poles. We show that the annual mean multi-model median is representative of the observations in Arctic, but that the intermodel spread is large. We also document the geographical distribution and seasonal cycle of the AOD for the individual aerosol species: black carbon (BC) from fossil fuel and biomass burning, sulfate, organic aerosols (OAs), dust, and sea-salt. For a subset of models that represent nitrate and secondary organic aerosols (SOAs), we document the role of these aerosols at high latitudes.

The seasonal dependence of natural and anthropogenic aerosols differs with natural aerosols peaking in winter (sea-salt) and spring (dust), whereas AOD from anthropogenic aerosols peaks in late spring and summer. The models produce a median annual mean AOD of 0.07 in the Arctic (defined here as north of 60° N). The models also predict a noteworthy aerosol transport to the Antarctic (south of 70° S) with a resulting AOD varying between 0.01 and 0.02. The models have estimated the shortwave anthropogenic radiative forcing contributions to the direct aerosol effect (DAE) associated with BC and OA from fossil fuel and biofuel (FF), sulfate, SOAs, nitrate, and biomass burning from BC and OA emissions combined. The Arctic modelled annual mean DAE is slightly negative (−0.12 W m−2), dominated by a positive BC FF DAE in spring and a negative sulfate DAE in summer. The Antarctic DAE is governed by BC FF. We perform sensitivity experiments with one of the AeroCom models (GISS modelE) to investigate how regional emissions of BC and sulfate and the lifetime of BC influence the Arctic and Antarctic AOD. A doubling of emissions in eastern Asia results in a 33 % increase in Arctic AOD of BC. A doubling of the BC lifetime results in a 39 % increase in Arctic AOD of BC. However, these radical changes still fall within the AeroCom model range.

Files

acp-17-12197-2017.xml

Files (239.6 kB)

Name Size Download all
md5:626c342b0a7d44ef679ae85f21c53d54
239.6 kB Preview Download

Additional details

Funding

European Commission
FRICON - Marie Curie cofunding of the FRICON mobility programme in the Research Council of Norway scheme for independent basic research projects 608695
European Commission
ACCESS - Arctic Climate Change, Economy and Society 265863
European Commission
ACCLAIM - Aerosols effects on convective clouds and climate 280025
European Commission
PEGASOS - Pan-European Gas-AeroSol-climate interaction Study 265148