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| Titel |
Bromine and Chlorine Chemistry at Santiago crater, Masaya Volcano - Nicaragua |
| VerfasserIn |
Nicole Bobrowski, Julio Alverez, Deanna Donohoue, Christoph Hörmann, Friedrich Wilhelm Klappenbach, Angélica Muñoz, Roland von Glasow, Ulrich Platt |
| 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 |
250076965
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| Zusammenfassung |
| In March 2011 a measurement campaign took place at the Santiago crater the currently only degassing crater of Masaya volcano, Nicaragua. Multi-Axis-Differential Optical Absorption Spectroscopy (MAX-DOAS) measurements were carried out at the crater rim and downwind in a valley about 1.5 km south-west from the emission source on eight consecutive days. These passive DOAS data were evaluated for BrO and SO2 slant column densities (SCDs) and BrO/SO2 ratios were calculated to overcome dilution effects and investigate the BrO formation processes of a volcanic plume in the planetary boundary layer as Masaya is located just 600 m.a.s.l. The BrO/SO2 ratios ranged from minimum values of 1.3•10^-5 at the crater rim to a maximum value of 7.2•10^-5 taken 1.5 km downwind. Interestingly on two days the BrO formation lead to a significant stronger enhancement BrO/SO2 ratio for the downwind measurement site in comparison with the other days. Furthermore, a generally small increase of the BrO/SO2 ratios could be observed for downwind as well as crater rim measurements after the first three days.
On six days and three nights filter-pack measurements were undertaken as well to determine the halogen/sulphur ratios. These resulted in Br/S ratios of the order of 10^-4 and Cl/S ratios of 10^-1. A clear difference in the halogen/sulfur ratio between night and day-time measurements could be observed and will be discussed. In parallel to the in-situ and remote sensing measurements meteorological data were collected with a meteorological station situated on the eastern side of the Santiago crater. Additionally on two days SO2 fluxes were determined by mobile measurements, traversing under the plume with a car in a distance of about 15 km.
The 2011 measurements will be put into a broader context comparing them to data taken during the last 15 years by various scientific groups. The data, their variation and possible causes for variations will be discussed. In particular for 2011 the discussion will be focused on meteorological influences. We will compare the data with results from a 1D numerical model that has been used for the investigation of volcanic plumes in the past. |
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