Stratospheric sulfur and its implications for radiative forcing simulated by the chemistry climate model EMAC.
Multiyear simulations with the atmospheric chemistry general circulation model EMAC with a microphysical modal aerosol module at high vertical resolution demonstrate that the sulfur gases COS and SO2, the latter from low-latitude and midlatitude volcanic eruptions, predominantly control the formation of stratospheric aerosol. Marine dimethyl sulfide (DMS) and other SO2sources, including strong anthropogenic emissions in China, are found to play a minor role except in the lowermost stratosphere. Estimates of volcanic SO2emissions are based on satellite observations using Total Ozone Mapping Spectrometer and Ozone Monitoring Instrument for total injected mass and Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) on Envisat or Stratospheric Aerosol and Gases Experiment for the spatial distribution. The 10 year SO2and COS data set of MIPAS is also used for model evaluation. The calculated radiative forcing of stratospheric background aerosol including sulfate from COS and small contributions by DMS oxidation, and organic aerosol from biomass burning, is about 0.07W/m2. For stratospheric sulfate aerosol from medium and small volcanic eruptions between 2005 and 2011 a global radiative forcing up to 0.2W/m2is calculated, moderating climate warming, while for the major Pinatubo eruption the simulated forcing reaches 5W/m2, leading to temporary climate cooling. The Pinatubo simulation demonstrates the importance of radiative feedback on dynamics, e.g., enhanced tropical upwelling, for large volcanic eruptions.
Atmospheric Chemistry Department, Max Planck Institute for Chemistry Mainz, Germany.
C
C
Brühl
Atmospheric Chemistry Department, Max Planck Institute for Chemistry Mainz, Germany ; Also at The Cyprus Institute Nicosia, Cyprus.
J
J
Lelieveld
Institute for Physics of the Atmosphere, Johannes Gutenberg University Mainz, Germany.
H
H
Tost
Institute for Meteorology and Climate Research, Karlsruhe Institute of Technology Karlsruhe, Germany.
M
M
Höpfner
Institute for Meteorology and Climate Research, Karlsruhe Institute of Technology Karlsruhe, Germany.
N
N
Glatthor
chemistry climate model; radiative forcing; stratospheric sulfur; volcanoes