Improved optical flow velocity analysis in SO&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt; camera images of volcanic plumes – implications for emission-rate retrievals investigated at Mt Etna, Italy and Guallatiri, Chile

Gliß, Jonas; Stebel, K.; Kylling, Arve; Sudbø, Asle

doi:10.5194/amt-11-781-2018

Cited by 25 publications

(23 citation statements)

References 49 publications

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“…by comparing the DOAS column densities to the measured plume optical densities in the DOAS field of view within the images and deriving a linear relationship. The plume velocity was determined at each pixel using a hybrid optical flow method that includes a correction for ill‐constrained plume tracking in the often‐homogeneous plume center (Gliß et al, 2018). Finally, the SO 2 emission rate was determined by multiplying the column density with the orthogonal plume velocity and integrating along a cross section of the gas plume near the volcano's vent (see Figure A1).…”

Section: Methodsmentioning

confidence: 99%

Linking Subsurface to Surface Using Gas Emission and Melt Inclusion Data at Mount Cleveland Volcano, Alaska

Werner

Rasmussen

Plank

et al. 2020

Geochem Geophys Geosyst

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Mount Cleveland is one of Alaska's most active volcanoes, yet little is known about the magmatic system driving persistent and dynamic volcanic activity. Volcanic gas and melt inclusion (MI) data from 2016 were combined to investigate shallow magmatic processes. SO2 emission rates were between 166 and 324 t/day and the H2O/SO2 was 600 ± 53, whereas CO2 and H2S were below detection. Olivine‐, clinopyroxene‐, and plagioclase‐hosted MIs have up to 3.8 wt.% H2O, 514 ppm CO2, and 2,320 ppm S. Equilibration depths, based on MI H2O contents, suggest that a magmatic column extended from 0.5 to 3.0 km (~10–60 MPa). We used MI data to empirically model open‐system H‐C‐S degassing from 0 to 12 km and found that a column of magma between 0.5 and 3 km could produce the measured gas H2O/SO2 ratio. However, additional magma deeper than 3 km is required to sustain emissions over periods greater than days to weeks, if the observed vent dimension is a valid proxy for the conduit. Assuming an initial S content of 2,320 ppm, the total magma supply needed to sustain the annual SO2 flux was 5 to 9.8 Mm3/yr, suggesting a maximum intrusive‐to‐extrusive ratio of 13:1. The model predicts degassing of <50 t/day CO2 for July 2016, which corresponds to a maximum predicted CO2/SO2 of 0.2. Ultimately, frequent recharge from deeper, less degassed magma is required to drive the continuous activity observed over multiple years. During periods of recharge we would expect lower H2O/SO2 and measurable volcanic CO2.

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Section: Methodsmentioning

confidence: 99%

Linking Subsurface to Surface Using Gas Emission and Melt Inclusion Data at Mount Cleveland Volcano, Alaska

Werner

Rasmussen

Plank

et al. 2020

Geochem Geophys Geosyst

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“…Several studies have examined potential error sources in wind speed determination using optical flow models (Peters et al, 2015;Klein et al, 2017;Gliß et al, 2018). Thus, for the case studies presented here, plume features in the SO 2 camera imagery were manually tracked to calculate plume speed.…”

Section: Plume Speed From So 2 Camera Imagerymentioning

confidence: 99%

Measuring SO2 Emission Rates at Kīlauea Volcano, Hawaii, Using an Array of Upward-Looking UV Spectrometers, 2014–2017

Elias

Kern

Horton³

et al. 2018

Front. Earth Sci.

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Retrieving accurate volcanic sulfur dioxide (SO 2) gas emission rates is important for a variety of purposes. It is an indicator of shallow subsurface magma, and thus may signal impending eruption or unrest. SO 2 emission rates are significant for accurately assessing climate impact, and providing context for assessing environmental, agricultural, and human health effects during volcanic eruptions. The U.S. Geological Survey Hawaiian Volcano Observatory uses an array of ten fixed, upward-looking ultraviolet spectrometer systems to measure SO 2 emission rates at 10-s sample intervals from the Kīlauea summit. We present Kīlauea SO 2 emission rates from the volcano's summit and middle East Rift Zone during 2014-2017 and discuss the major sources of error for these measurements. Due to the wide range of SO 2 emissions encountered at the summit vent, we used a variable wavelength spectral analysis range to accurately quantify both high and low SO 2 column densities. We compare measured emission rates from the fixed spectrometer array to independent road and helicopter-based traverse measurements and evaluate the magnitudes and sources of uncertainties for each method. To address the challenge of obtaining accurate plume speed measurements, we examine ground-based wind-speed, plume speed tracking via spectrometer, and SO 2 camera derived plume speeds. Our analysis shows that: (1) the summit array column densities calculated using a dual fit window, are within −6 to +22% of results obtained with a variety of other conventional and experimental retrieval methods; (2) emission rates calculated from the summit array located ∼3 km downwind provide the best, practical estimate of summit SO 2 release under normal trade wind conditions; (3) ground-based anemometer wind speeds are 22% less than plume speeds determined by cross-correlation of plume features; (4) our best estimate of average Kīlauea SO 2 release for 2014-2017 is 5100 t/d, which is comparable to the space-based OMI emissions of 5518 t/d; and (5) short-term variability of SO 2 emissions reflects Kīlauea lava lake dynamics.

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“…Windspeeds for calculating SO 2 fluxes can also be obtained directly from UV im-Corresponding author: tehnuka@volcanofiles.com age sequences [e.g. Gliß et al 2018;Peters and Oppenheimer 2018], whereas windspeeds for DOAS flux calculations often require the use of multiple scanners and cross-correlation [McGonigle et al 2009;Galle et al 2010], independent windspeeds from in situ measurements [e.g. Prata 2013], or forecast models [Lübcke et al 2013].…”

Section: Introductionmentioning

confidence: 99%

Degassing at Sabancaya volcano measured by UV cameras and the NOVAC network

Ilanko

Pering²,

Wilkes³

et al. 2019

Volcanica

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We used low-cost Raspberry Pi ultraviolet (UV) cameras to measure sulphur dioxide (SO 2 ) fluxes from Sabancaya volcano, Peru, during eruptive activity on 27 April 2018. Light dilution corrections were made by operating instruments at two distances simultaneously. Estimated SO 2 fluxes of 27.1 kg s −1 are higher than previously reported, likely due to the current eruptive episode (ongoing since November 2016). Each eruptive event included frequent (2-3 per minute), ash-rich emissions, forming gas pulses with masses of 3.0-8.2 tonnes SO 2 . Sustained degassing and lack of overpressure suggest open-vent activity. Mean fluxes are consistent with those measured by a permanent NOVAC station (25.9 kg s −1 ) located under the plume, with remaining differences likely due to windspeed estimates and sampling rate. Our work highlights the importance of accurate light dilution and windspeed modelling in SO 2 retrievals and suggests that co-location of UV cameras with permanent scanning spectrometers may be valuable in providing accurate windspeeds. ResumenUtilizamos cámaras ultravioletas (UV) Raspberry Pi para medir los flujos de dióxido de azufre (SO 2 ) en el volcán Sabancaya, Perú, durante la actividad del 27 abril 2018. La corrección por dilución de luz se realizó midiendo simultáneamente en dos sitios a diferentes distancias. Los flujos promedio (27.1 kg s −1 ) son superiores a los reportados previamente, probablemente debido al actual episodio explosivo. Cada evento tuvo frecuentes emanaciones ricas en ceniza y gas, emitiendo 3.0-8.2 toneladas de SO 2 . La desgasificación sostenida, sin sobrepresión, indica una chimenea abierta. Estos flujos son similares a los medidos en una estación permanente de NOVAC (25.9 kg s −1 ) debajo de la pluma. La diferencia restante es por velocidad del viento estimada y la frecuencia de la muestreo. Nuestro trabajo muestra la importancia de modelar con precisión la dilución de luz y velocidad del viento, y que co-instalar cámaras UV y espectrómetros permanentes podrían dar velocidades del viento más exactos.

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Improved optical flow velocity analysis in SO<sub>2</sub> camera images of volcanic plumes – implications for emission-rate retrievals investigated at Mt Etna, Italy and Guallatiri, Chile

Cited by 25 publications

References 49 publications

Linking Subsurface to Surface Using Gas Emission and Melt Inclusion Data at Mount Cleveland Volcano, Alaska

Linking Subsurface to Surface Using Gas Emission and Melt Inclusion Data at Mount Cleveland Volcano, Alaska

Measuring SO2 Emission Rates at Kīlauea Volcano, Hawaii, Using an Array of Upward-Looking UV Spectrometers, 2014–2017

Degassing at Sabancaya volcano measured by UV cameras and the NOVAC network

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