Volcanic SO&lt;sub&gt;2&lt;/sub&gt; and SiF&lt;sub&gt;4&lt;/sub&gt; visualization and their ratio monitored using 2-D thermal emission spectroscopy

Abstract. The composition and emission rates of volcanic gas plumes provide insight of the geologic internal activity, atmospheric chemistry, aerosol formation and radiative processes around it. Observations are necessary for public security and the aviation industry. Ground-based thermal emission infrared spectroscopy, which uses the radiation of the volcanic gas itself, allows for continuously monitoring during day and night from a save distance. We present measurements on Popocatépetl volcano based on thermal emission spectroscopy during different campaigns between 2006–2009 using a Scanning Infrared Gas Imaging System (SIGIS). The experimental set-up, measurement geometries and analytical algorithms are described. The equipment was operated from a safe distance of 12 km from the volcano at two different spectral resolutions: 0.5 and 4 cm−1. The 2-dimensional scanning capability of the instrument allows for an on-line visualization of the volcanic SO2 plume, animation and determination of its propagation speed. SiF4 was also identified in the infrared spectra recorded at both resolutions. The SiF4/SO2 molecular ratio can be calculated from each image and used as a highly useful parameter to follow changes in volcanic activity. A small Vulcanian eruption was monitored during the night of 16 to 17 November 2008 which was confirmed from the strong ash emission registered around 01:00 a.m. LST (Local Standard Time) and a pronounced SO2 cloud was registered. Enhanced SiF4/SO2 ratios were observed before and after the eruption. A validation of the results from thermal emission measurements with those from absorption spectra of the moon taken at the same time, as well as an error analysis, are presented. The inferred propagation speed from sequential imagees is used to calculate the emission rates at different distances from the crater.

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Volcanic SO2 and SiF4 visualization using 2-D thermal emission spectroscopy – Part 1: Slant-columns and their ratios

Atmospheric Measurement Techniques ◽

10.5194/amt-5-275-2012 ◽

2012 ◽

Vol 5 (2) ◽

pp. 275-288 ◽

Cited By ~ 24

Author(s):

W. Stremme ◽

A. Krueger ◽

R. Harig ◽

M. Grutter

Keyword(s):

Emission Spectroscopy ◽

Thermal Emission ◽

Aviation Industry ◽

Subsequent Paper ◽

Emission Rates ◽

Aerosol Formation ◽

Safe Distance ◽

Volcanic Gas ◽

Radiative Processes ◽

Thermal Emission Spectroscopy

Abstract. The composition and emission rates of volcanic gas plumes provide insight of the geologic internal activity, atmospheric chemistry, aerosol formation and radiative processes around it. Observations are necessary for public security and the aviation industry. Ground-based thermal emission infrared spectroscopy, which uses the radiation of the volcanic gas itself, allows for continuously monitoring during day and night from a safe distance. We present measurements on Popocatépetl volcano based on thermal emission spectroscopy during different campaigns between 2006–2009 using a Scanning Infrared Gas Imaging System (SIGIS). The experimental set-up, measurement geometries and analytical algorithms are described. The equipment was operated from a safe distance of 12 km from the volcano at two different spectral resolutions: 0.5 and 4 cm−1. The 2-dimensional scanning capability of the instrument allows for an on-line visualization of the volcanic SO2 plume and its animation. SiF4 was also identified in the infrared spectra recorded at both resolutions. The SiF4/SO2 molecular ratio can be calculated from each image and used as a highly useful parameter to follow changes in volcanic activity. A small Vulcanian eruption was monitored during the night of 16 to 17 November 2008 and strong ash emission together with a pronounced SO2 cloud was registered around 01:00 a.m. LST (Local Standard Time). Enhanced SiF4/SO2 ratios were observed before and after the eruption. A validation of the results from thermal emission measurements with those from absorption spectra of the moon taken at the same time, as well as an error analysis, are presented. The inferred propagation speed from sequential images is used in a subsequent paper (Part 2) to calculate the emission rates at different distances from the crater.

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Volcanic SO2 and SiF4 visualization using 2-D thermal emission spectroscopy – Part 2: Wind propagation and emission fluxes

Atmospheric Measurement Techniques Discussions ◽

10.5194/amtd-5-4599-2012 ◽

2012 ◽

Vol 5 (4) ◽

pp. 4599-4633 ◽

Cited By ~ 1

Author(s):

A. Krueger ◽

W. Stremme ◽

R. Harig ◽

M. Grutter

Keyword(s):

Wind Field ◽

Emission Spectroscopy ◽

Thermal Emission ◽

Diagnostic Tools ◽

Volcanic Plume ◽

Reconstruction Method ◽

Emission Flux ◽

Volcanic Gas ◽

Reconstruction Methods ◽

Thermal Emission Spectroscopy

Abstract. The technique for measuring two-dimensional (2-D) plumes of volcanic gases with thermal emission spectroscopy was described in Part 1 by Stremme et al. (2012). In that paper the instrumental aspects as well as retrieval strategies for obtaining the slant column images of SO2 and SiF4, as well as animations of particular events observed at the Popocatépetl volcano, were presented. This work focuses on the procedures for determining the propagation speed of the gases and estimating an emission flux from the given image sequences. A 2-D column density distribution of a volcanic gas, available as time-consecutive frames, provides information of a wind-field and the average velocity at which the volcanic plume is propagating. The presented reconstruction method solves the equation of continuity as an ill-posed problem using mainly a Tikhonov-like regularization. It is observed from the available data sets that if the main direction of propagation is perpendicular to the line-of-sight, the algorithm works well for SO2 which has the strongest signals, and also for SiF4 in some favourable cases. Due to the similarity of the algorithm used here with the reconstruction methods used for profile retrievals based on optimal estimation theory, diagnostic tools like the averaging kernels can be calculated analogously and the information can be quantified as degrees of freedom. Thus, it is shown that the combination of wind-field and column distribution of the gas plume can provide the emission flux of the volcano both during day and night.

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Volcanic SO2 and SiF4 visualization using 2-D thermal emission spectroscopy – Part 2: Wind propagation and emission rates

Atmospheric Measurement Techniques ◽

10.5194/amt-6-47-2013 ◽

2013 ◽

Vol 6 (1) ◽

pp. 47-61 ◽

Cited By ~ 10

Author(s):

A. Krueger ◽

W. Stremme ◽

R. Harig ◽

M. Grutter

Keyword(s):

Wind Field ◽

Emission Spectroscopy ◽

Emission Rate ◽

Thermal Emission ◽

Diagnostic Tools ◽

Volcanic Plume ◽

Reconstruction Method ◽

Emission Rates ◽

Reconstruction Methods ◽

Thermal Emission Spectroscopy

Abstract. A technique for measuring two-dimensional (2-D) plumes of volcanic gases with thermal emission spectroscopy was described in Part 1 by Stremme et al. (2012a). In that paper the instrumental aspects as well as retrieval strategies for obtaining the slant column images of SO2 and SiF4, as well as animations of particular events observed at the Popocatépetl volcano, were presented. This work focuses on the procedures for determining the propagation speed of the gases and estimating an emission rate from the given image sequences. A 2-D column density distribution of a volcanic gas, available as time-consecutive frames, provides information of a projected wind field and the average velocity at which the volcanic plume is propagating. This information is valuable since the largest uncertainties when calculating emission rates of the gases using remote sensing techniques arise from propagation velocities which are often inadequately assumed. The presented reconstruction method solves the equation of continuity as an ill-posed problem using mainly a Tikhonov-like regularisation. It is observed from the available data sets that if the main direction of propagation is perpendicular to the line-of-sight, the algorithm works well for SO2, which has the strongest signals, and also for SiF4 in some favourable cases. Due to the similarity of the algorithm used here with the reconstruction methods used for profile retrievals based on optimal estimation theory, diagnostic tools like the averaging kernels can be calculated in an analogous manner and the information can be quantified as degrees of freedom. Thus, it is shown that the combination of wind field and column distribution of the gas plume can provide the emission rate of the volcano both during day and night.

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