MIPAS observations of volcanic sulphate aerosol and sulphur dioxide in the stratosphere

Günther, Annika; Griessbach, Sabine; Sinnhuber, Björn-Martin; von Clarmann, Thomas; Höpfner, Michael; Stiller, Gabriele; Deshler, Terry

doi:10.5194/acp-2017-538

Journal Article

FZJ-2018-00712

MIPAS observations of volcanic sulphate aerosol and sulphur dioxide in the stratosphere

Günther, A. (Corresponding author) ; Höpfner, M. ; Sinnhuber, B.-M. ; Griessbach, S.FZJ* ; Deshler, T. ; von Clarmann, T. ; Stiller, G.

2017
EGU Katlenburg-Lindau

Atmospheric chemistry and physics / Discussions 538, 1 - 32 (2017) [10.5194/acp-2017-538]

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Please use a persistent id in citations: http://hdl.handle.net/2128/16684 doi:10.5194/acp-2017-538

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° 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.

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