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| Titel |
Short-term climatic impact of the 1991 volcanic eruption of Mt. Pinatubo and effects on atmospheric tracers |
| VerfasserIn |
G. Pitari, E. Mancini |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1561-8633
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| Digitales Dokument |
URL |
| Erschienen |
In: Natural Hazards and Earth System Science ; 2, no. 1/2 ; Nr. 2, no. 1/2, S.91-108 |
| Datensatznummer |
250000269
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| Publikation (Nr.) |
 copernicus.org/nhess-2-91-2002.pdf |
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| Zusammenfassung |
| Large explosive
volcanic eruptions are capable of injecting considerable amounts of
particles and sulphur gases (mostly sulphur dioxide) above the tropopause,
causing increases in the stratospheric aerosol optical depth that may be
even larger than one order of magnitude. The e-folding particle lifetime
in the stratosphere is much longer than in the troposphere (one year
versus a few days) so that climatic perturbations in a timeframe of a few
years are produced after major volcanic eruptions. A climate-chemistry
coupled model is used here to study the dynamical effects of the radiative
forcing due to stratospheric aerosols formed after the June, 1991
cataclysmic eruption of Mt. Pinatubo in the Philippines. It is shown that
the dynamical perturbation is twofold: (a) the stratospheric mean
meridional circulation is affected by local aerosol radiative heating
(mostly located in the tropical lower stratosphere); (b) the planetary
wave propagation in the mid- to high-latitude lower stratosphere is
altered as a consequence of decreasing atmospheric stability due to the
climatic perturbation. Dynamical results of the climate model are compared
with available observations; a discussion is made regarding the
similarities with the dynamical regime of the easterly phase of the
equatorial quasi-biennial oscillation. Major findings of this study are:
(a) radiatively forced changes in the stratospheric circulation during the
first two years after the eruption may, to a large extent, explain the
observed trend decline of long-lived greenhouse gases (CH4 and N2O, in
particular); (b) the dynamical perturbation helps explain why simple
photochemical studies of the ozone trends during 1991–1993 generally
fail in reproducing the satellite observed feature consisting of a 2%
additional global ozone depletion during 1993 with respect to 1992. In
both cases we conclude that an increase in the mid- to high-latitude
downward flux at the tropopause is the key factor for explaining the
behaviour of these atmospheric tracers during 1991/92. |
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