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| Titel |
The first climatology of stratospheric SO2 |
| VerfasserIn |
Michael Höpfner, Christoph Brühl, Norbert Glatthor, Udo Grabowski, Sylvia Kellmann, Michael Kiefer, Jos Lelieveld  , Andrea Linden, Johannes Orphal, Gabriele Stiller, Thomas v. Clarmann |
| Konferenz |
EGU General Assembly 2013
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 15 (2013) |
| Datensatznummer |
250074443
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| Zusammenfassung |
| Sulphur dioxide (SO2) is one of the key species determining the aerosol content of the
stratosphere. Apart from this study, only three measured profiles of SO2 concentrations (by
ATMOS) covering the altitude range of the stratosphere have been published, two of which
are heavily perturbed by the Pinatubo eruption and one by El Chichon. Here we present a
climatology of monthly and 10° zonal mean profiles of SO2 volume mixing ratios in the
altitude range 15-45 km as derived from MIPAS/Envisat measurements from July 2002 until
April 2012. The vertical resolution varies from 3.5-4 km in the lower stratosphere up to
6-10 km at the upper end of the profiles with estimated total errors of 5-20 pptv for
background conditions of SO2. Comparisons are made with few available observations of
SO2 up to high altitudes from ATMOS, for volcanically perturbed situations in the
lower stratosphere from ACE-FTS and at the lowest altitudes with stratospheric
in-situ observations. The dataset proves for the first time several features of the
stratospheric SO2 distribution, which up to now, have only been shown by models: (1)
the local maximum of SO2 at around 25-30 km altitude from conversion of COS
as the pre-curser of the Junge layer and (2) the downwelling of SO2-rich air to
altitudes of 25-30 km at high latitudes during winter and its subsequent depletion
during spring as cause for the sudden appearance of enhanced concentrations of
condensation nuclei. Comparison with model results of SO2 from the SPARC aerosol
assessment report indicate several inconsistencies between simulations and our
observations. Further, dedicated EMAC model runs reveal that the strong increase of
SO2 to values of 80-100 pptv in the upper stratosphere can only be explained by
taking into account visible and near-IR photolysis of H2SO4 and, in addition, a
meteoritic sink. Lower stratospheric variability of SO2 can mainly be explained
by volcanic activity. A modulation of the mid-stratospheric maximum could be
observed for several equatorial eruptions during the time period of observations. |
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