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| Titel |
Analysis of global methane changes after the 1991 Pinatubo volcanic eruption |
| VerfasserIn |
N. Bândă, M. Krol, M. Weele, T. Noije, T. Röckmann |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 13, no. 4 ; Nr. 13, no. 4 (2013-02-27), S.2267-2281 |
| Datensatznummer |
250018436
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| Publikation (Nr.) |
 copernicus.org/acp-13-2267-2013.pdf |
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| Zusammenfassung |
| The global methane (CH4) growth rate showed large variations after the
eruption of Mount Pinatubo in June 1991. Both sources and sinks of
tropospheric CH4 were altered following the eruption, by feedback
processes between climate and tropospheric photochemistry. Such processes
include Ultra Violet (UV) radiative changes due to the presence of volcanic
sulfur dioxide (SO2) and sulphate aerosols in the stratosphere, and due to
stratospheric ozone depletion. Changes in temperature and water vapour in the
following years caused changes in tropospheric chemistry, as well as in
natural emissions. We present a sensitivity study that investigates the
relative effects that these processes had on tropospheric CH4
concentrations, using a simple one-dimensional chemistry model representative
for the global tropospheric column. To infer the changes in UV radiative
fluxes, the chemistry model is coupled to a radiative transfer model. We find
that the overall effect of natural processes after the eruption on the CH4
growth rate is dominated by the reduction in CH4 lifetime due to
stratospheric ozone depletion. However, all the other processes are found to
have non-negligible effects, and should therefore be taken into account in
order to obtain a good estimate of CH4 concentrations after Pinatubo.
We find that the overall effect was a small initial increase in the CH4
growth rate after the eruption, followed by a decrease of about 7 ppb yr−1
by mid-1993. When changes in anthropogenic emissions are employed according
to emission inventories, an additional decrease of about 5 ppb yr−1 in
the CH4 growth rate is obtained between the years 1991 and 1993. The
results using the simplified single column model are in good qualitative
agreement with observed changes in the CH4 growth rate. Further analysis,
taking into account changes in the dynamics of the atmosphere, variations in
emissions from biomass burning, and in biogenic emissions of non-methane
volatile organic compounds (NMVOC), requires the use of a full
three-dimensional model. |
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