 |
| Titel |
Atmospheric impact of the 1783–1784 Laki eruption: Part I Chemistry modelling |
| VerfasserIn |
D. S. Stevenson, C. E. Johnson, E. J. Highwood, V. Gauci, W. J. Collins, R. G. Derwent |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1680-7316
|
| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 3, no. 3 ; Nr. 3, no. 3 (2003-05-19), S.487-507 |
| Datensatznummer |
250001027
|
| Publikation (Nr.) |
 copernicus.org/acp-3-487-2003.pdf |
|
|
|
|
|
| Zusammenfassung |
| Results
from the first chemistry-transport model study of the impact of the 1783–1784
Laki fissure eruption (Iceland: 64°N, 17°W) upon atmospheric composition
are presented. The eruption released an estimated 61 Tg(S) as SO2
into the troposphere and lower stratosphere. The model has a high
resolution tropopause region, and detailed sulphur chemistry. The
simulated SO2 plume spreads over much of the Northern
Hemisphere, polewards of ~40°N. About 70% of the SO2 gas is
directly deposited to the surface before it can be oxidised to sulphuric
acid aerosol. The main SO2 oxidants, OH and H2O2,
are depleted by up to 40% zonally, and the lifetime of SO2
consequently increases. Zonally averaged tropospheric SO2
concentrations over the first three months of the eruption exceed 20 ppbv,
and sulphuric acid aerosol reaches ~2 ppbv. These compare to modelled
pre-industrial/present-day values of 0.1/0.5 ppbv SO2 and
0.1/1.0 ppbv sulphate. A total sulphuric acid aerosol yield of 17–22
Tg(S) is produced. The mean aerosol lifetime is 6–10 days, and the peak
aerosol loading of the atmosphere is 1.4–1.7 Tg(S) (equivalent to 5.9–7.1
Tg of hydrated sulphuric acid aerosol). These compare to modelled
pre-industrial/present-day sulphate burdens of 0.28/0.81 Tg(S), and
lifetimes of 6/5 days, respectively. Due to the relatively short
atmospheric residence times of both SO2 and sulphate, the
aerosol loading approximately mirrors the temporal evolution of emissions
associated with the eruption. The model produces a reason-able simulation
of the acid deposition found in Greenland ice cores. These results appear
to be relatively insensitive to the vertical profile of emissions assumed,
although if more of the emissions reached higher levels (>12 km), this
would give longer lifetimes and larger aerosol yields. Introducing the
emissions in episodes generates similar results to using monthly mean
emissions, because the atmospheric lifetimes are similar to the repose
periods between episodes. Most previous estimates of the global aerosol
loading associated with Laki did not use atmospheric models; this study
suggests that these earlier estimates have been generally too large in
magnitude, and too long-lived. Environmental effects following the Laki
eruption may have been dominated by the widespread deposition of SO2
gas rather than sulphuric acid aerosol. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|