Journal cover Journal topic
Atmospheric Chemistry and Physics An interactive open-access journal of the European Geosciences Union
Journal topic

Journal metrics

Journal metrics

  • IF value: 5.509 IF 5.509
  • IF 5-year value: 5.689 IF 5-year
    5.689
  • CiteScore value: 5.44 CiteScore
    5.44
  • SNIP value: 1.519 SNIP 1.519
  • SJR value: 3.032 SJR 3.032
  • IPP value: 5.37 IPP 5.37
  • h5-index value: 86 h5-index 86
  • Scimago H <br class='hide-on-tablet hide-on-mobile'>index value: 161 Scimago H
    index 161
Volume 14, issue 23
Atmos. Chem. Phys., 14, 13063-13079, 2014
https://doi.org/10.5194/acp-14-13063-2014
© Author(s) 2014. This work is distributed under
the Creative Commons Attribution 3.0 License.
Atmos. Chem. Phys., 14, 13063-13079, 2014
https://doi.org/10.5194/acp-14-13063-2014
© Author(s) 2014. This work is distributed under
the Creative Commons Attribution 3.0 License.

Research article 09 Dec 2014

Research article | 09 Dec 2014

The impact of volcanic aerosol on the Northern Hemisphere stratospheric polar vortex: mechanisms and sensitivity to forcing structure

M. Toohey1, K. Krüger1,2, M. Bittner3,4, C. Timmreck3, and H. Schmidt3 M. Toohey et al.
  • 1GEOMAR Helmholtz Centre for Ocean Research Kiel, Kiel, Germany
  • 2University of Oslo, Department of Geosciences, Oslo, Norway
  • 3Max Planck Institute for Meteorology, Hamburg, Germany
  • 4International Max Planck Research School on Earth System Modeling (IMPRS), Hamburg, Germany

Abstract. Observations and simple theoretical arguments suggest that the Northern Hemisphere (NH) stratospheric polar vortex is stronger in winters following major volcanic eruptions. However, recent studies show that climate models forced by prescribed volcanic aerosol fields fail to reproduce this effect. We investigate the impact of volcanic aerosol forcing on stratospheric dynamics, including the strength of the NH polar vortex, in ensemble simulations with the Max Planck Institute Earth System Model. The model is forced by four different prescribed forcing sets representing the radiative properties of stratospheric aerosol following the 1991 eruption of Mt. Pinatubo: two forcing sets are based on observations, and are commonly used in climate model simulations, and two forcing sets are constructed based on coupled aerosol–climate model simulations. For all forcings, we find that simulated temperature and zonal wind anomalies in the NH high latitudes are not directly impacted by anomalous volcanic aerosol heating. Instead, high-latitude effects result from enhancements in stratospheric residual circulation, which in turn result, at least in part, from enhanced stratospheric wave activity. High-latitude effects are therefore much less robust than would be expected if they were the direct result of aerosol heating. Both observation-based forcing sets result in insignificant changes in vortex strength. For the model-based forcing sets, the vortex response is found to be sensitive to the structure of the forcing, with one forcing set leading to significant strengthening of the polar vortex in rough agreement with observation-based expectations. Differences in the dynamical response to the forcing sets imply that reproducing the polar vortex responses to past eruptions, or predicting the response to future eruptions, depends on accurate representation of the space–time structure of the volcanic aerosol forcing.

Publications Copernicus
Download
Short summary
Earth system model simulations are used to investigate the impact of volcanic aerosol forcing on stratospheric dynamics, e.g. the Northern Hemisphere (NH) polar vortex. We find that mechanisms linking aerosol heating and high-latitude dynamics are not as direct as often assumed; high-latitude effects result from changes in stratospheric circulation and related vertical motions. The simulated responses also show evidence of being sensitive to the structure of the volcanic forcing used.
Earth system model simulations are used to investigate the impact of volcanic aerosol forcing on...
Citation
Share