Search results for "DOAS"

The novel HALO mini-DOAS instrument: inferring trace gas concentrations from airborne UV/visible limb spectroscopy under all skies using the scaling …

2017

Abstract. We report on a novel six-channel optical spectrometer (further on called mini-DOAS instrument) for airborne nadir and limb measurements of atmospheric trace gases, liquid and solid water, and spectral radiances in the UV/vis and NIR spectral ranges. The spectrometer was developed for measurements from aboard the German High-Altitude and Long-Range (HALO) research aircraft during dedicated research missions. Here we report on the relevant instrumental details and the novel scaling method used to infer the mixing ratios of UV/vis absorbing trace gases from their absorption measured in limb geometry. The uncertainties of the scaling method are assessed in more detail than before for …

Tracking Formation of a Lava Lake From Ground and Space: Masaya Volcano (Nicaragua), 2014-2017

2018

A vigorously degassing lava lake appeared inside the Santiago pit crater of Masaya volcano (Nicaragua) in December 2015, after years of degassing with no (or minor) incandescence. Here we present an unprecedented-long (3 years) and continuous volcanic gas record that instrumentally characterizes the (re)activation of the lava lake. Our results show that, before appearance of the lake, the volcanic gas plume composition became unusually CO 2 rich, as testified by high CO 2 /SO 2 ratios (mean: 12.2 ± 6.3) and low H 2 O/CO 2 ratios (mean: 2.3 ± 1.3). The volcanic CO 2 flux also peaked in November 2015 (mean: 81.3 ± 40.6 kg/s; maximum: 247 kg/s). Using results of magma degassing models and budg…

Development and application of active and passive DOAS instrumentation for the remote sensing measurement of volcanic gas emissions and continuous ge…

2011

Volcanic gas emissions and degassing dynamics at Ubinas and Sabancaya volcanoes; implications for the volatile budget of the central volcanic zone

2017

Abstract Emission of volcanic gas is thought to be the dominant process by which volatiles transit from the deep earth to the atmosphere. Volcanic gas emissions, remain poorly constrained, and volcanoes of Peru are entirely absent from the current global dataset. In Peru, Sabancaya and Ubinas volcanoes are by far the largest sources of volcanic gas. Here, we report the first measurements of the compositions and fluxes of volcanic gases emitted from these volcanoes. The measurements were acquired in November 2015. We determined an average SO 2 flux of 15.3 ± 2.3 kg s − 1 (1325-ton day − 1 ) at Sabancaya and of 11.4 ± 3.9 kg s − 1 (988-ton day − 1 ) at Ubinas using scanning ultraviolet spectr…

Variation of the BrO/SO2 molar ratio in the plume of Tungurahua volcano between 2007 and 2017 and its relationship to volcanic activity

2019

International audience; Recent long-term observations of the bromine monoxide (BrO) to sulphur dioxide (SO2) molar ratio in volcanic plumes have suggested a link between changes in the BrO/SO2 ratio and the volcanic activity. Nevertheless, understanding of the mechanisms determining this link is still limited due to the lack of studies on volcanic bromine release from the melt into the atmosphere. We present the results of 10 years (2007–2017) of observations of the BrO/SO2 molar ratio in the volcanic plume of Tungurahua volcano, Ecuador. Following the nearly continuous eruptive activity from 1999 to 2008, Tungurahua showed alternating phases of eruptive activity separated by periods of qui…

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

2018

Retrieving accurate volcanic sulfur dioxide (SO2) 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. SO2 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 SO2 emission rates at 10-s sample intervals from the Kīlauea summit. We present Kīlauea SO2 emission rates from the volcano’s summit and middle East Rift Zo…

Measurements of volcanic SO2 and CO2 fluxes by combined DOAS, Multi-GAS and FTIR observations: a case study from Turrialba and Telica volcanoes

2014

Over the past few decades, substantial progress has been made to overcome the technical difficulties of continuously measuring volcanic SO2 emissions. However, measurements of CO2 emissions still present many difficulties, partly due to the lack of instruments that can directly measure CO2 emissions and partly due to its strong atmospheric background. In order to overcome these difficulties, a commonly taken approach is to combine differential optical absorption spectroscopy (DOAS) by using NOVAC scan-DOAS instruments for continuous measurements of crateric SO2 emissions, and electrochemical/NDIR multi-component gas analyser system (multi-GAS) instruments for measuring CO2/SO2 ratios of exc…

Spectroscopic capture of 1 Hz volcanic SO2fluxes and integration with volcano geophysical data

2009

[1] Here we present a novel spectroscopic approach to capturing, with unprecedented time resolution and accuracy, volcanic SO2 fluxes. This is based on two USB2000 spectrometers, coupled to cylindrical lens telescopes, each collecting light which has transited horizontal sections of the rising plume. We report on field data from Stromboli volcano, in which the entire emission rate from the volcano was measured, as well as flux signatures associated with individual crater explosions. The latter were integrated with seismic and thermal data, demonstrating correlations in both cases, and representing the first such geophysical-geochemical data corroboration on this timescale. Such a holistic e…