Intercomparison of SO 2 camera systems for imaging volcanic gas plumes

Kern, Christoph; Lübcke, Peter; Bobrowski, Nicole; Campion, Robin; Mori, Toshiya; Smekens, J. F.; Stebel, Kerstin; Tamburello, Giancarlo; Burton, Mike; Platt, U.; Prata, Fred

doi:10.1016/j.jvolgeores.2014.08.026

Cited by 47 publications

(67 citation statements)

References 21 publications

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“…The variability is high, depending on the degassing phase of activity with emission rates varying from 11 kg s −1 (Oppenheimer et al, 2006), to 82.2 kg s −1 (Teggi et al, 1999). A proper, statistical evaluation and intercomparison of the IR camera retrievals is beyond the scope of this paper, but new work resulting from a volcanic plume workshop, where several UV cameras and the IR camera are compared, has been submitted for publication (Kern et al, 2014;Prata et al, 2014;Lopez et al, 2014). …”

Section: Etna Volcano Italymentioning

confidence: 99%

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Retrieval of sulfur dioxide from a ground-based thermal infrared imaging camera

Prata

Bernardo

2014

Atmos. Meas. Tech.

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Abstract. Recent advances in uncooled detector technology now offer the possibility of using relatively inexpensive thermal (7 to 14 µm) imaging devices as tools for studying and quantifying the behaviour of hazardous gases and particulates in atmospheric plumes. An experimental fast-sampling (60 Hz) ground-based uncooled thermal imager (Cyclops), operating with four spectral channels at central wavelengths of 8.6, 10, 11 and 12 µm and one broadband channel (7-14 µm) has been tested at several volcanoes and at an industrial site, where SO 2 was a major constituent of the plumes. This paper presents new algorithms, which include atmospheric corrections to the data and better calibrations to show that SO 2 slant column density can be reliably detected and quantified. Our results indicate that it is relatively easy to identify and discriminate SO 2 in plumes, but more challenging to quantify the column densities. A full description of the retrieval algorithms, illustrative results and a detailed error analysis are provided. The noise-equivalent temperature difference (NE T ) of the spectral channels, a fundamental measure of the quality of the measurements, lies between 0.4 and 0.8 K, resulting in slant column density errors of 20 %. Frame averaging and improved NE T 's can reduce this error to less than 10 %, making a stand-off, day or night operation of an instrument of this type very practical for both monitoring industrial SO 2 emissions and for SO 2 column densities and emission measurements at active volcanoes. The imaging camera system may also be used to study thermal radiation from meteorological clouds and the atmosphere.

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Section: Etna Volcano Italymentioning

confidence: 99%

“…Within this region no SO 2 can be retrieved, and consequently the total SCD for the whole plume will be underestimated. Kern et al (2014) report measurements from a several UV camera systems during an inter-comparison experiment on Stromboli…”

Section: Stromboli Volcano Italymentioning

confidence: 99%

Retrieval of sulfur dioxide from a ground-based thermal infrared imaging camera

Prata

Bernardo

2014

Atmos. Meas. Tech.

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“…Carbon dioxide (CO 2 ) is the second most abundant volatile species of degassing magma [1,2]. Measuring CO 2 mass emission rates (fluxes) therefore provides a powerful sampling tool that can be used, for example, to constrain magma crystallization processes related to the magma dynamics [3], learn about the geochemical carbon cycle [4] or for monitoring and early warning of volcanic unrest [5,6].…”

Section: Introductionmentioning

confidence: 99%

“…Remote sensing, notably active, laser-based remote sensing is feasible to acquire spatially integrated measurements of CO 2 concentrations. This technique is therefore ideal to probe extended degassing geometry by means of a forward model.…”

Section: Introductionmentioning

confidence: 99%

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Ground-Based Remote Sensing of Volcanic CO2 Fluxes at Solfatara (Italy)—Direct Versus Inverse Bayesian Retrieval

et al. 2018

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CO 2 is the second most abundant volatile species of degassing magma. CO 2 fluxes carry information of incredible value, such as periods of volcanic unrest. Ground-based laser remote sensing is a powerful technique to measure CO 2 fluxes in a spatially integrated manner, quickly and from a safe distance, but it needs accurate knowledge of the plume speed. The latter is often difficult to estimate, particularly for complex topographies. So, a supplementary or even alternative way of retrieving fluxes would be beneficial. Here, we assess Bayesian inversion as a potential technique for the case of the volcanic crater of Solfatara (Italy), a complex terrain hosting two major CO 2 degassing fumarolic vents close to a steep slope. Direct integration of remotely sensed CO 2 concentrations of these vents using plume speed derived from optical flow analysis yielded a flux of 717 ± 121 t day −1 , in agreement with independent measurements. The flux from Bayesian inversion based on a simple Gaussian plume model was in excellent agreement under certain conditions. In conclusion, Bayesian inversion is a promising retrieval tool for CO 2 fluxes, especially in situations where plume speed estimation methods fail, e.g., optical flow for transparent plumes. The results have implications beyond volcanology, including ground-based remote sensing of greenhouse gases and verification of satellite soundings.

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Intense magmatic degassing through the lake of Copahue volcano, 2013–2014

et al. 2015

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Here we report on the first assessment of volatile fluxes from the hyperacid crater lake hosted within the summit crater of Copahue, a very active volcano on the Argentina‐Chile border. Our observations were performed using a variety of in situ and remote sensing techniques during field campaigns in March 2013, when the crater hosted an active fumarole field, and in March 2014, when an acidic volcanic lake covered the fumarole field. In the latter campaign, we found that 566 to 1373 t d−1 of SO2 were being emitted from the lake in a plume that appeared largely invisible. This, combined with our derived bulk plume composition, was converted into flux of other volcanic species (H2O ~ 10989 t d−1, CO2 ~ 638 t d−1, HCl ~ 66 t d−1, H2 ~ 3.3 t d−1, and HBr ~ 0.05 t d−1). These levels of degassing, comparable to those seen at many open‐vent degassing arc volcanoes, were surprisingly high for a volcano hosting a crater lake. Copahue's unusual degassing regime was also confirmed by the chemical composition of the plume that, although issuing from a hot (65°C) lake, preserves a close‐to‐magmatic signature. EQ3/6 models of gas‐water‐rock interaction in the lake were able to match observed compositions and demonstrated that magmatic gases emitted to the atmosphere were virtually unaffected by scrubbing of soluble (S and Cl) species. Finally, the derived large H2O flux (10,988 t d−1) suggested a mechanism in which magmatic gas stripping drove enhanced lake water evaporation, a process likely common to many degassing volcanic lakes worldwide.

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Intercomparison of SO 2 camera systems for imaging volcanic gas plumes

Cited by 47 publications

References 21 publications

Retrieval of sulfur dioxide from a ground-based thermal infrared imaging camera

Retrieval of sulfur dioxide from a ground-based thermal infrared imaging camera

Ground-Based Remote Sensing of Volcanic CO2 Fluxes at Solfatara (Italy)—Direct Versus Inverse Bayesian Retrieval

Intense magmatic degassing through the lake of Copahue volcano, 2013–2014

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