Ground-Based Remote Sensing and Imaging of Volcanic Gases and Quantitative Determination of Multi-Species Emission Fluxes

Platt, U.; Bobrowski, Nicole; Butz, A.

doi:10.3390/geosciences8020044

Cited by 24 publications

(29 citation statements)

References 129 publications

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“…Gradients in the BrO distributions can give insight into in-plume halogen chemistry (see e.g. Bobrowski et al, 2007;von Glasow, 2010;Roberts et al, 2014). The NO 2 scenario (blue spectral range) is applicable to measurements of stack emissions at, for example, a coal power plant (see e.g.…”

Section: Detection Principlementioning

confidence: 99%

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Towards imaging of atmospheric trace gases using Fabry–Pérot interferometer correlation spectroscopy in the UV and visible spectral range

et al. 2019

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Abstract. Many processes in the lower atmosphere including transport, turbulent mixing and chemical conversions happen on timescales of the order of seconds (e.g. at point sources). Remote sensing of atmospheric trace gases in the UV and visible spectral range (UV–Vis) commonly uses dispersive spectroscopy (e.g. differential optical absorption spectroscopy, DOAS). The recorded spectra allow for the direct identification, separation and quantification of narrow-band absorption of trace gases. However, these techniques are typically limited to a single viewing direction and limited by the light throughput of the spectrometer set-up. While two-dimensional imaging is possible by spatial scanning, the temporal resolution remains poor (often several minutes per image). Therefore, processes on timescales of seconds cannot be directly resolved by state-of-the-art dispersive methods. We investigate the application of Fabry–Pérot interferometers (FPIs) for the optical remote sensing of atmospheric trace gases in the UV–Vis spectral range. By choosing a FPI transmission spectrum, which is optimised to correlate with narrow-band (ideally periodic) absorption structures of the target trace gas, column densities of the trace gas can be determined with a sensitivity and selectivity comparable to dispersive spectroscopy, using only a small number of spectral channels (FPI tuning settings). Different from dispersive optical elements, the FPI can be implemented in full-frame imaging set-ups (cameras), which can reach high spatio-temporal resolution. In principle, FPI correlation spectroscopy can be applied for any trace gas with distinct absorption structures in the UV–Vis range. We present calculations for the application of FPI correlation spectroscopy to SO2, BrO and NO2 for exemplary measurement scenarios. In addition to high sensitivity and selectivity we find that the spatio temporal resolution of FPI correlation spectroscopy can be more than 2 orders of magnitude higher than state-of-the-art DOAS measurements. As proof of concept we built a 1-pixel prototype implementing the technique for SO2 in the UV. Good agreement with our calculations and conventional measurement techniques is demonstrated and no cross sensitivities to other trace gases are observed.

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Section: Detection Principlementioning

confidence: 99%

“…SO 2 camera, ∼ 1 Hz for volcanic emissions; see e.g. Mori and Burton, 2006;Bluth et al, 2007;Kern et al, 2010;Platt et al, 2018) or a tuneable BPF as a wavelength selective element (e.g. NO 2 camera, ∼ 3 min per image for stack emissions of power plants; Dekemper et al, 2016).…”

Section: Introductionmentioning

confidence: 99%

Towards imaging of atmospheric trace gases using Fabry–Pérot interferometer correlation spectroscopy in the UV and visible spectral range

et al. 2019

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“…However, the high gas concentrations and limited atmospheric entrainment in young, proximal plumes yield high quality data that record faithfully primary degassing processes at a temporal resolution approaching that of geophysical data (≤1 Hz). Remote measurements, such as can be acquired using imaging or spectral techniques (e.g., UV/IR‐cameras and COSPEC/scanning‐differential optical absorption spectroscopy (DOAS)/FlySpec/mobile‐DOAS, respectively), are typically performed several kilometers from the volcanic gas source and therefore pose little to no direct risk to volcanologists or equipment (e.g., Bluth et al, ; Edmonds et al, ; Galle et al, ; Holland et al, ; Horton et al, ; McGonigle et al, , ; Moffat & Millan, ; Mori & Burton, ; Oppenheimer et al, ; Platt et al, ; Tamburello et al, , ; Weibring et al, ; Wilkes et al, ). Note that, although significant progress has been made in the use of Light Detection And Ranging (LIDAR) for remote sensing of CO 2 (Santoro et al, ), SO 2 is currently the only gas species able to be measured routinely by remote methods due to its strong absorption at UV wavelengths and the negligible concentration in ambient air.…”

Section: Introductionmentioning

confidence: 99%

Dynamics of Outgassing and Plume Transport Revealed by Proximal Unmanned Aerial System (UAS) Measurements at Volcán Villarrica, Chile

Liu

Wood

Mason

et al. 2019

Geochem Geophys Geosyst

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Volcanic gas emissions are intimately linked to the dynamics of magma ascent and outgassing and, on geological time scales, constitute an important source of volatiles to the Earth's atmosphere. Measurements of gas composition and flux are therefore critical to both volcano monitoring and to determining the contribution of volcanoes to global geochemical cycles. However, significant gaps remain in our global inventories of volcanic emissions, (particularly for CO 2 , which requires proximal sampling of a concentrated plume) for those volcanoes where the near-vent region is hazardous or inaccessible. Unmanned Aerial Systems (UAS) provide a robust and effective solution to proximal sampling of dense volcanic plumes in extreme volcanic environments. Here we present gas compositional data acquired using a gas sensor payload aboard a UAS flown at Volcán Villarrica, Chile. We compare UAS-derived gas time series to simultaneous crater rim multi-GAS data and UV camera imagery to investigate early plume evolution. SO 2 concentrations measured in the young proximal plume exhibit periodic variations that are well correlated with the concentrations of other species. By combining molar gas ratios (CO 2 /SO 2 = 1.48-1.68, H 2 O/SO 2 = 67-75, and H 2 O/CO 2 = 45-51) with the SO 2 flux (142 ± 17 t/day) from UV camera images, we derive CO 2 and H 2 O fluxes of~150 t/day and~2,850 t/day, respectively. We observe good agreement between time-averaged molar gas ratios obtained from simultaneous UAS-and ground-based multi-GAS acquisitions. However, the UAS measurements made in the young, less diluted plume reveal additional short-term periodic structure that reflects active degassing through discrete, audible gas exhalations.

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“…In studies of this kind, SO 2 is one of the most prominent gases to measure. Beside the dependence of its gas fraction and emission rate on sub surface magmatic processes, it features properties like a high abundance in volcanic plumes, a low atmospheric background, a relatively long (typically days) atmospheric lifetime and favorable optical absorption properties, which make it easy to detect and an excellent plume tracer (Caroll and Holloway, 1994;Oppenheimer et al, 2011;Platt et al, 2018). Remote sensing of SO 2 has become well-established among volcanologists to determine abundance and total emission rate from safe distance and at low logistic effort (e.g., Moffat and Millan, 1971;Oppenheimer et al, 1998;Galle et al, 2003;Horton et al, 2006;Mori and Burton, 2006), however, its in-situ detection remains a crucial complemental tool, e.g., to achieve high spatial resolution or more accurate measurements and for the validation of remote sensing instruments.…”

Section: Introductionmentioning

confidence: 99%

Non-dispersive UV Absorption Spectroscopy: A Promising New Approach for in-situ Detection of Sulfur Dioxide

et al. 2019

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A new type of instrument for in-situ detection of volcanic sulfur dioxide is presented on the basis of non-dispersive UV absorption spectroscopy. It is a promising alternative to presently used compact and low-cost SO 2 monitoring techniques, over which it has a series of advantages, including an inherent calibration, fast response times (< 2 s to reach 90 % of the applied concentration), a measurement range spanning about 5 orders of magnitude and small, well-known cross sensitivities to other gases. Compactness, cost-efficiency and detection limit (< 1 ppm, few ppb under favorable conditions) are comparable to other presently used in-situ instruments. Our instrument prototype has been extensively tested in comparison studies with established methods. In autumn 2015, diverse volcanic applications were investigated such as fumarole sampling, proximal plume measurements and airborne measurements several kilometers downwind from the vent on Mt. Etna and White Island. General capabilities and limitations of the measurement principle are discussed, considering different instrument configurations and future applications.

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Ground-Based Remote Sensing and Imaging of Volcanic Gases and Quantitative Determination of Multi-Species Emission Fluxes

Cited by 24 publications

References 129 publications

Towards imaging of atmospheric trace gases using Fabry–Pérot interferometer correlation spectroscopy in the UV and visible spectral range

Towards imaging of atmospheric trace gases using Fabry–Pérot interferometer correlation spectroscopy in the UV and visible spectral range

Dynamics of Outgassing and Plume Transport Revealed by Proximal Unmanned Aerial System (UAS) Measurements at Volcán Villarrica, Chile

Non-dispersive UV Absorption Spectroscopy: A Promising New Approach for in-situ Detection of Sulfur Dioxide

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