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- Title
MIPAS observations of volcanic sulphate aerosol and sulphur dioxide in the stratosphere.
- Authors
Günther, Annika; Höpfner, Michael; Sinnhuber, Björn-Martin; Griessbach, Sabine; Deshler, Terry; von Clarmann, Thomas; Stiller, Gabriele
- Abstract
Volcanic eruptions can increase the stratospheric sulphur content by orders of magnitude above the background level and are the most important source of variability of stratospheric sulphur loading. We present a set of vertical profiles of sulphate aerosol volume densities and derived liquid-phase H2SO4 mole-fractions for 2005-2012, retrieved from infrared limb emission measurements by the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) on board of the Environmental Satellite. The MIPAS aerosol dataset has been corrected for a possible altitude-dependent bias by comparison with balloon-borne in situ aerosol measurements at Laramie, Wyoming. The MIPAS data of stratospheric sulphate aerosol is linked to MIPAS observations of sulphur dioxide (SO2) with the help of Chemical Transport Model simulations. We investigate the production of sulphate aerosol and its fate from volcanically emitted SO2 for two volcanic case studies: the eruptions of Kasatochi in 2008 and Sarychev in 2009, which both occurred in the Northern Hemisphere mid-latitudes during boreal summer. We show that the MIPAS sulphate aerosol and SO2 data are qualitatively and quantitatively consistent to each other. Further, we demonstrate that the lifetime of SO2 is well described by its oxidation by hydroxyl radicals. While sedimentation of the sulphate aerosol plays a role, we find that the dominant mechanism controlling the stratospheric lifetime of sulphur after these volcanic eruptions at mid-latitudes is transport in the Brewer-Dobson circulation. Sulphur emitted by the two mid-latitude volcanoes resides mostly north of 30°â€‰N at altitudes of ~ 10-16 km, while at higher altitudes (~ 18-22 km) part of the volcanic sulphur is transported towards the equator where it is lifted into the stratospheric overworld and can further be transported into both hemispheres.
- Subjects
SULFATES &; the environment; VOLCANIC eruptions; ATMOSPHERIC aerosols; AEROSOLS &; the environment; SULFUR dioxide &; the environment; STRATOSPHERE
- Publication
Atmospheric Chemistry & Physics Discussions, 2017, p1
- ISSN
1680-7367
- Publication type
Article
- DOI
10.5194/acp-2017-538