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Department of Geography, University of Cambridge, Cambridge, UK
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- PublicationRestrictedVolcanic sulphur dioxide fluxes from Etna, Vulcano and Stromboli measured with an automated scanning ultraviolet spectrometer(2003)
; ; ; ; ; ; ; ; ;Mc’Gonigle, A. J. S.; Department of Geography, University of Cambridge, Cambridge, UK ;Oppenheimer, C.; Department of Geography, University of Cambridge, Cambridge, UK. ;Hayes, A. R.; Department of Geography, University of Cambridge, Cambridge, UK ;Galle, B.; 2Department of Radio and Space Science, Chalmers University of Technology, Gothenburg, Sweden ;Edmonds, M.; Montserrat Volcano Observatory, Montserrat, West Indies ;Caltabiano, T.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Salerno, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Burton, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia; ;; ; ; ; ; Stromboli made in July 2002 from fixed positions, using an automated plume scanning technique. Spectral data were collected using a miniature ultraviolet spectrometer, and SO2 column amounts were derived with a differential optical absorption spectroscopy evaluation routine. Scanning through the plume was enabled by a 45 turning mirror affixed to the shaft of a computer controlled stepper motor, so that scattered skylight from incremental angles within the horizon-to-horizon scans was reflected into the field of view of the spectrometer. Each scan lasted _5 min and, by combining these data with wind speeds, average fluxes of 940, 14, and 280 Mg d_1 were obtained for Etna, Vulcano, and Stromboli, respectively. For comparative purposes, conventional road and airborne traverses were also made using this spectrometer, yielding fluxes of 850, 17, and 210 Mg d_1. The automated scanning technique has the advantage of obviating the need for time-consuming traverses underneath the plume and is well suited for longer-term telemetered deployments to provide sustained high time resolution flux data.184 26 - PublicationRestrictedAccurate measurement of volcanic SO2 flux: Determination of plume transport speed and integrated SO2 concentration with a single device(2005-02-09)
; ; ; ; ; ;McGonigle, A. J. S.; Department of Geography, University of Cambridge, Downing Place, Cambridge CB2 3EN, UK ;Inguaggiato, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Palermo, Palermo, Italia ;Aiuppa, A.; Dipartimento CFTA, Universita` di Palermo, Via Archirafi 36, Palermo ;Hayes, A.R.; Department of Geography, University of Cambridge, Downing Place, Cambridge ;Oppenheimer, C.; Department of Geography, University of Cambridge, Downing Place, Cambridge; ; ; ; Ground-based measurements of volcanic sulfur dioxide fluxes are important indicators of volcanic activity, with application in hazard assessment, and understanding the impacts of volcanic emissions upon the environment and climate. These data are obtained by making traverses underneath the volcanic plume a few kilometers from source with an ultraviolet spectrometer, measuring integrated SO2 concentrations across the plume’s cross section, and multiplying by the plume’s transport speed. However, plume velocities are usually derived from ground-based anemometers, located many kilometers from the traverse route and hundreds of meters below plume altitude, complicating the experimental design and introducing large flux (can be >100%) errors. Here we present the first report of a single instrument capable of (accurate) volcanic SO2 flux measurements. This device records integrated SO2 concentrations and plume heights during traverses. Between traverses, two in-plume SO2 time series are measured from underneath the plume with the instrument, corresponding to zenith and inclined (user-specified angle from vertical in the direction of the volcano) fields of view, respectively. The distance between the points of intersection of the two views with the plume is found on the basis of the determined plume height, and the two signals are cross-correlated to determine the lag between them, enabling accurate derivation of the wind speed. We present flux data (with errors ±12%) obtained in this way at Mt. Etna during July 2004.474 190