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| Titel |
Mapping the BrO/SO2 ratio in the plume of Popocatépetl, Mexico with Imaging-DOAS |
| VerfasserIn |
Johannes Zielcke, Peter Luebcke, Leif Vogel, Nicole Bobrowski, Ulrich Platt |
| Konferenz |
EGU General Assembly 2015
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250112633
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| Publikation (Nr.) |
 EGU/EGU2015-12798.pdf |
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| Zusammenfassung |
| Differential Optical Absorption Spectroscopy (DOAS) in the ultraviolet and visible
wavelength region has become a widespread tool, not only to study the chemistry of trace
gases such as sulphur dioxide (SO2) and halogen oxides (e.g. BrO, OClO) in volcanic
plumes. It can also be used for volcano monitoring by observing SO2 fluxes and the molar
ratio of BrO to SO2, which is a possible precursor for dynamic changes in the shallow
part of a volcanic system like other halogen/sulfur ratios. This acquisition of this
ratio is convenient as it can be measured with comparatively simple UV DOAS
instruments.
Imaging-DOAS (IDOAS) utilizes the push-broom or whisk-broom technique to create a
hyperspectral image of a section of the sky, then the DOAS evaluation is applied to each pixel
to derive trace gas slant column densities (SCDs). Hereby images of the SO2 and BrO
distribution can be created, allowing to study the chemistry in different parts of the plume.
This is especially interesting for the case of BrO, which is produced in the atmosphere and
not directly emitted by volcanoes.
Here we present IDOAS measurements carried out at Popocatépetl volcano, Mexico,
during April 2010 and 2011. SO2 SCDs of up to 2 /
1018ÂmoleculesÂcm-2 and BrO SCDs
of up to 7 /
1013ÂmoleculesÂcm-2 were detected. The determined BrO/SO2 ratios range
around 3 /
10-5, comparable to several other volcanoes in the Americas. An increase in the
determined BrO/SO2 ratios with distance from the vent, i.e. plume age, can be
observed. |
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