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| Titel |
Early in-flight detection of SO2 via Differential Optical Absorption Spectroscopy: a feasible aviation safety measure to prevent potential encounters with volcanic plumes |
| VerfasserIn |
L. Vogel, B. Galle, C. Kern, H. Delgado Granados, V. Conde, P. Norman, S. Arellano, O. Landgren, P. Lübcke, J. M. Alvarez Nieves, L. Cárdenas Gonzáles, U. Platt |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1867-1381
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Measurement Techniques ; 4, no. 9 ; Nr. 4, no. 9 (2011-09-08), S.1785-1804 |
| Datensatznummer |
250002090
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| Publikation (Nr.) |
 copernicus.org/amt-4-1785-2011.pdf |
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| Zusammenfassung |
Volcanic ash constitutes a risk to aviation, mainly due to its ability to
cause jet engines to fail. Other risks include the possibility of abrasion of
windshields and potentially serious damage to avionic systems. These hazards
have been widely recognized since the early 1980s, when volcanic ash provoked
several incidents of engine failure in commercial aircraft. In addition to
volcanic ash, volcanic gases also pose a threat. Prolonged and/or cumulative
exposure to sulphur dioxide (SO2) or sulphuric acid (H2SO4)
aerosols potentially affects e.g. windows, air frame and may cause permanent
damage to engines. SO2 receives most attention among the gas species
commonly found in volcanic plumes because its presence above the lower
troposphere is a clear proxy for a volcanic cloud and indicates that fine ash
could also be present.
Up to now, remote sensing of SO2 via Differential Optical Absorption
Spectroscopy (DOAS) in the ultraviolet spectral region has been used to
measure volcanic clouds from ground based, airborne and satellite platforms.
Attention has been given to volcanic emission strength, chemistry inside
volcanic clouds and measurement procedures were adapted accordingly. Here we
present a set of experimental and model results, highlighting the feasibility
of DOAS to be used as an airborne early detection system of SO2 in
two spatial dimensions. In order to prove our new concept, simultaneous
airborne and ground-based measurements of the plume of Popocatépetl
volcano, Mexico, were conducted in April 2010. The plume extended at an
altitude around 5250 m above sea level and was approached and traversed at the
same altitude with several forward looking DOAS systems aboard an airplane.
These DOAS systems measured SO2 in the flight direction and at
±40 mrad (2.3°) angles relative to it in both, horizontal and
vertical directions. The approaches started at up to 25 km distance to the
plume and SO2 was measured at all times well above the detection
limit. In combination with radiative transfer studies, this study indicates
that an extended volcanic cloud with a concentration of 1012 molecules cm−3 at typical flight levels of 10 km can be detected
unambiguously at distances of up to 80 km away. This range provides enough
time (approx. 5 min) for pilots to take action to avoid entering a
volcanic cloud in the flight path, suggesting that this technique can be used
as an effective aid to prevent dangerous aircraft encounters with potentially
ash rich volcanic clouds. |
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