AS1.33 | Infrasound, acoustic-gravity waves, and atmospheric dynamics
Infrasound, acoustic-gravity waves, and atmospheric dynamics
Convener: Alexis Le Pichon | Co-conveners: Patrick HupeECSECS, Alain Hauchecorne, Gunter Stober, Sven Peter Näsholm
Orals
| Tue, 16 Apr, 10:45–12:30 (CEST)
 
Room M2
Posters on site
| Attendance Mon, 15 Apr, 10:45–12:30 (CEST) | Display Mon, 15 Apr, 08:30–12:30
 
Hall X5
Posters virtual
| Attendance Mon, 15 Apr, 14:00–15:45 (CEST) | Display Mon, 15 Apr, 08:30–18:00
 
vHall X5
Orals |
Tue, 10:45
Mon, 10:45
Mon, 14:00
The field of infrasonic research, the science of low-frequency acoustic waves, has expanded to include acoustic-gravity waves and developed into a broad interdisciplinary field encompassing several academic disciplines of geophysics as well as recent technical and basic scientific developments. The International Monitoring System (IMS) infrasound network for nuclear-test-ban verification and regional infrasound arrays deployed around the globe have demonstrated their capacity for detecting and locating various natural and anthropogenic disturbances. Infrasound and acoustic-gravity waves are capable of traveling up to thermospheric altitudes and over enormous ranges, where the wind and temperature structure controls their propagation. Recent studies have offered new insights on quantitative relationships between infrasonic observations and atmospheric dynamics, opening a new field for atmospheric remote sensing.

New studies using lidar, radar, microwave spectrometer, and mesospheric airglow observations complemented by satellite measurements help better determine the interaction between atmospheric layers and the influence of atmospheric waves on the mean flow. It is expected that further developing multi-instrument platforms will improve gravity wave parameterizations and enlarge the science community interested in operational infrasound monitoring. In a higher frequency range, the infrasound monitoring system also offers unique opportunities to provide, in near-real time, continuous relevant information about natural hazards with high societal impact, such as volcanic eruptions, surface earthquakes, meteoroids, and bright fireballs.

We invite contributions on recent studies characterizing infrasound sources or atmospheric phenomena using complementary technologies. We particularly encourage presentations utilizing acoustic waves to probe the atmosphere at both small and large scales. Results and advances in acoustic propagation modeling, signal processing and machine learning applications are also welcome. Another focus is on derived data products and services for civilian and scientific applications as well as on innovative instrumentation, which also encompasses sensors attached to moving or elevated platforms such as balloons. We also invite seismo-acoustic studies on the coupled Earth’s crust – ocean – atmosphere system and, in particular, on the ionospheric manifestations of physical processes in the ocean and in the solid Earth.

Orals: Tue, 16 Apr | Room M2

The oral presentations are given in a hybrid format supported by a Zoom meeting featuring on-site and virtual presentations. The button to access the Zoom meeting appears just before the time block starts.
Chairpersons: Alexis Le Pichon, Gunter Stober, Sven Peter Näsholm
10:45–10:50
10:50–11:10
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EGU24-8572
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AS1.33
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ECS
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solicited
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Highlight
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On-site presentation
Marouchka Froment, Zongbo Xu, Philippe Lognonné, Carene Larmat, Raphael F Garcia, Mélanie Drilleau, Brent G Delbridge, Aymeric Spiga, Taichi Kawamura, and Eric Beucler

In-situ measurements of atmospheric variables are key to the validation and improvement of current models of the Martian climate, particularly of the planetary boundary layer. This highly dynamical region, whose thickness and altitude vary, is governed by unique thermodynamical, physical and chemical exchanges between the troposphere and surface. However, only sparse data is available in this location, as information is collected mostly by a few surface probes and during occasional spacecraft descent and landing. 

Recently, the seismometers of the InSight lander recorded short low-frequency, dispersed waveforms on six occasions. These signals were shown to be impact-generated guided infrasound waves. They were excited by the atmospheric entry and surface impact of bolides, and propagated  in a low-altitude atmospheric waveguide. The location of their source, i.e., the impact crater, is well characterized by orbital imaging and the origin time by joint seismic and acoustic analysis. The deformation of the ground by the propagating infrasound wave allowed their detection by InSight seismometers.

Using analytical modeling, we show that the signal group velocity depends on the vertical profile of the effective sound speed in the Martian boundary layer. These impact-generated signals provide a unique opportunity to probe the atmosphere at these low altitudes. Here, we conduct a Bayesian inversion of effective sound speed up to  ~2000 m altitude using the group velocity measured for events S0981c, S0986c and S1034a. We compare these results with estimates of effective sound speed profiles provided by the Mars Climate Database based on global circulation models. We show that the differences between inverted and modeled profiles can be attributed to a local variation in wind in the impact → station direction, with amplitude smaller than 2 m/s, and that the infrasound data generally validates the Mars Climate Database results for each date and location.

How to cite: Froment, M., Xu, Z., Lognonné, P., Larmat, C., Garcia, R. F., Drilleau, M., Delbridge, B. G., Spiga, A., Kawamura, T., and Beucler, E.: Probing the Martian atmospheric boundary layer using impact-generated seismo-acoustic signals, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8572, https://doi.org/10.5194/egusphere-egu24-8572, 2024.

11:10–11:20
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EGU24-7749
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AS1.33
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Highlight
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On-site presentation
Solene Gerier, Roland Martin, and Raphael Garcia

Inferring a model of the wind, pressure, velocity in the atmosphere is an inverse problem, for which the state of the art methods use the travel times of acoustic waves.
We aim to solve such an inverse problem by adding more information and using a full waveform (in this case pressure variation) as infrasound observation.
In particular, we place our study in the context of an inversion of infrasound due to an explosion (or quake) in a domain, without gravity, without attenuation but with the wind as a non isotropic parameter. The addition of wind is important because wind can have an significant impact on the waveform (like the wave guide). 
To this end, we adapted the adjoint method developed in seismology to a fluid in movement : sensitivity kernels have been computed in the case of acoustics waves in the presence of wind (linearised Navier-Stokes equations).
The sensitivity kernels play the role of a gradient in an optimization framework that recovers the variation of atmospheric parameters (density, wind, pressure, speed).
Sensitivity kernels have been studied on simple and more realistic cases in 1d and 2d.
We validated the sensitivity kernels acquired by the adjoint method by comparing them with those obtained by auto-differentiation. Discontinuities near the source and receivers are observed in the sensitivity kernels. We studied the influence of source frequency on the kernels and on these discontinuities.
These encouraging results on sensitivity kernels led us to test initial synthetic inversion in 1d and 2d.
We proposed an analysis of the efficiency of the inversion depending on the choice of parametrization, conjugate gradient method and regularization term.

How to cite: Gerier, S., Martin, R., and Garcia, R.: Development of a full waveform inversion method for acoustic waves in the presence of wind: application to synthetic and realistic cases , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7749, https://doi.org/10.5194/egusphere-egu24-7749, 2024.

11:20–11:30
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EGU24-3150
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AS1.33
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ECS
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On-site presentation
Benjamin Poste, Karim Abed-Meraim, Maurice Charbit, Alexis Le Pichon, Constantino Listowski, François Roueff, and Julien Vergoz

We present an improvement of the Multi-Channel Maximum-Likelihood (MCML) method [1]. This approach is based on the likelihood function derived from a multi-sensor stochastic model expressed in different frequency channels. Using the likelihood function, we determine, for the detection problem, the Generalized Likelihood Ratio (GLR) with a p-value threshold to discriminate signal of interest and noise. For the estimation of the slowness vector, we determine the Maximum Likelihood Estimation (MLE). Comparisons with synthetic and real datasets show that MCML, when implemented in the time-frequency domain, outperforms state-of-the-art detection algorithms in terms of detection probability and false alarm rate in poor signal-to-noise ratio scenarios. Mathematical extension of MCML is implemented in order to detect overlapping coherent signals in the same time frequency domain. This extension is based on the spectral matrix content. Taking into account the last detected source, the array response in the spectral matrix is iteratively subtracted to estimate a subsequent source of weaker energy. We show that the implemented approach allows detecting overlapping signals in the same time frequency window under various scenarios with varying signal-to-noise ratio (SNR), frequency bands and array geometry. Compared with the original method based on multiple maxima selection on the monosource likelihood function, the new approach yields improved wave parameter estimates. Results are illustrated by synthetics and real data recorded by stations part of the International Monitoring System (IMS).

 

[1] B. Poste et al. (2022), The Multi-Channel Maximum-Likelihood (MCML) method: a new approach for infrasound detection and wave parameter estimation, Geophysical Journal International, https://doi.org/10.1093/gji/ggac377

How to cite: Poste, B., Abed-Meraim, K., Charbit, M., Le Pichon, A., Listowski, C., Roueff, F., and Vergoz, J.: The Multi-Channel Maximum-Likelihood (MCML) method: towards a cost-effective multisource estimation algorithm, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3150, https://doi.org/10.5194/egusphere-egu24-3150, 2024.

11:30–11:40
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EGU24-17819
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AS1.33
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ECS
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On-site presentation
Duccio Gheri, Giacomo Belli, Emanuele Marchetti, Vincent Boulenger, Alexis Le Pichon, Patrick Hupe, Peter Näsholm, and Pierrick Mialle

Detecting and promptly reporting ongoing volcanic eruptions is crucial in supporting Volcanic Ash Advisory Centers (VAACs) in their mission to inform about ash clouds that may endanger aviation. Nevertheless, many active volcanoes lack local monitoring systems. Long-range infrasound monitoring, which holds the potential to detect and notify volcanic explosive events, could offer valuable insights. Numerous studies have already emphasized the utility of long-range infrasound data for this purpose, which led to the proposal of several monitoring approaches. 
The Volcanic Information System (VIS), developed in the framework of the FP7 and H2020 ARISE projects, is one of the most recent approaches for reporting ongoing eruptive events in near real-time based on process data from a single infrasound array. However, uncertainties still persist regarding its effectiveness and reliability. VIS is based on the Infrasound Parameter, IP, a detection algorithm originally developed for local monitoring and later adapted to long-range volcanic infrasound observations.
In this study, we investigate the efficiency of VIS considering 10 years (2010-2019) of data provided by 16 infrasound arrays of the International Monitoring System (IMS) established and provisionally operated by the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO). These 16 arrays are located in the most active volcanic regions of the world, encompassing multiple eruptions that range in energy from mild explosions to eruption classified with a VEI (Volcanic Explosivity Index) ≥ 4. To evaluate the reliability of the VIS algorithm and estimate the rate of false alerts (false positives), we compared the notifications provided for the entire period of analysis with reports from the Global Volcanism Program (GVP). 
Our results show that VIS is well designed for long-lasting (> few minutes), large (VEI >3) eruptions, such as Sub-Plinian/Plinian events or highly sustained Vulcanian/Strombolian explosions, while it typically misses single transient events. In terms of ranges, its reliability is strongly azimuth-dependent, with the best results at IMS range (up to 2000 km) achieved under favourable propagation conditions while limited to shorter distances (~1000 km) otherwise. Despite that improvements are possible by azimuthal deflation with the computational of 3D ray-tracing, unresolved ambiguity often remains due to the short angular distances between volcanoes with respect to the array. This issue can be solved by considering volcanic sectors rather than single edifices. In this context, we show that the VIS reliability significantly increases and might provide critical information to the VAACs, automatically and in near real-time, to trigger an independent analysis of ongoing volcanic eruptions.
This study was financially supported by the National Recovery and Resilience Plan, Mission 4 Component 2 - Investment 1.4 - NATIONAL CENTER FOR HPC, BIG DATA AND QUANTUM COMPUTING - funded by the European Union - NextGenerationEU - CUPB83C22002830001.

How to cite: Gheri, D., Belli, G., Marchetti, E., Boulenger, V., Le Pichon, A., Hupe, P., Näsholm, P., and Mialle, P.: Long range monitoring of explosive volcanoes with IMS infrasound arrays: testing the VIS, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17819, https://doi.org/10.5194/egusphere-egu24-17819, 2024.

11:40–11:50
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EGU24-16177
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AS1.33
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On-site presentation
Ulrike Mitterbauer, Ewald Brückl, Peter Carniel, and Stefan Mertl

The mobile Infrasound Array ISCO of the Austrian National Data Center at GeoSphere Austria is a part of the Central and Eastern European Infrasound Network (CEEIN). It was installed early 2021 at the Trafelberg, with the premises of the Conrad Observatory in Lower Austria. In 2022 and 2023 a multitude of signals caused by production blasts of a quarry in a distance of 16 km to the array were detected at the station ISCO. Approximately 20 signals were selected, analyzed and compared not only with the data of the seismic station CONA at the Conrad Observatory but also with the recordings of the Macro Seismic Sensor Network, a local low cost sensor network. Blasting parameters were provided by the operator. In addition, video recordings for the blast process and photogrammetric surveys of the blasted rock mass are available for selected events. This data provides information about the source mechanism for the recorded infrasound signals. Analysis of waveform showed that envelopes of the investigated signals are bell-shaped. Values of peak-to-peak amplitudes range between 0.16 and 0.38 Pascal, the half widths of the envelopes vary from 1 to 3 seconds and the frequency range covers 0.25 to 6.35 Hertz. Products of the peak-to-peak amplitudes and half widths show a significant correlation (R2 = 0.6) with the total explosive charge of the blasts.

Data assessment indicates that the change of rock volume caused by the explosion generates the infrasound signal. The videos of the blasting process show an initial expansion of the blasted rock mass, followed by the deposition in front of the blasting area. We interpret the primary increase of volume and the subsequent compaction during the deposition as the source mechanism of the infrasound signal. Numerical modelling of the volume changes during the overall blasting process allows for the calculation of the infrasound source and Green’s functions.

How to cite: Mitterbauer, U., Brückl, E., Carniel, P., and Mertl, S.: Infrasound signals generated by production blasts in a nearby quarry, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16177, https://doi.org/10.5194/egusphere-egu24-16177, 2024.

11:50–12:00
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EGU24-8096
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AS1.33
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ECS
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On-site presentation
Pierre-Yves Froissart, Philippe Lognonné, Pierre Simoneau, and Kiwamu Nishida

Nightglow radiation is a very good marker of high-altitude dynamics. After a first detection of a tsunami signature by a camera in the O+ emission (red airglow at 250km) in 2011, only a few other tsunami detections have been recorded and none have been observed in OH SWIR emission, which is the brightest of all the nightglow emissions and the only compatible for shorter periods signals, such as seismic waves. On the other hand, these acoustic waves associated with earthquakes are systematically detected by other ionospheric instruments (GPS, radar), they have never been directly observed by an airglow camera.  Can they be also detected by airglow?

We present here our strategy for such proof of concept. If achieved, it will provide unique access to seismic waves propagation where ground instruments are not available:  oceans, which cover more than 70% of the Earth's surface, but also to provide the harsh planetary environment of Venus, where airglow also exists and where it is not possible to send spacecraft to the ground.

The recent development of SWIR cameras and the first detection of infrasound in OH radiation in 2020 opened the way for these detections. To better understand the continuous dynamics of the OH layer, we have deployed a first camera at La Réunion island in May 2023. Another one will be installed on the Japanese island of Oshima in February-March 2024 to try to detect the signature of a seismic event if one occurs during the course of this scientific study. The presentation details our methodology for observing the airglow OH perturbations, from the instrument specifications to the first results of almost one year-acquisition at la Réunion and the expected events that we will observe from Japan.

How to cite: Froissart, P.-Y., Lognonné, P., Simoneau, P., and Nishida, K.: OH airglow SWIR observations: high temporal resolution acquisition for ionospheric seismology proof of concept, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8096, https://doi.org/10.5194/egusphere-egu24-8096, 2024.

12:00–12:10
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EGU24-9840
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AS1.33
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ECS
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Highlight
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On-site presentation
Ewen Jaffré, Christophe Bellisario, Philippe Keckhut, Pierre-Yves Froissart, Samuel Trémoulu, Fabrice Chane-Ming, Pierre Simoneau, Alain Hauchecorne, and Stéphane Saillant

Lower ionosphere is the theater of interactions between the ionized atmosphere and homogeneous atmosphere. Some phenomena such as gravity and acoustic waves which originate from the homogeneous atmosphere also impact the ionosphere and are suspected to be the source of sporadic disturbances in the E-region. Our goal is to correlate these disturbances to acoustic and gravity waves through modelling and ionosphere sounding. We first present the first steps towards this goal, a bi-dimensionnal, inviscid and compressible acoustic-gravity wave model coupled to a nightglow emission model (NEMO).  Then subsequent cross-comparisons with acoustic and gravity waves seen in the OH nightglow emission layer using an infrared sensor and MRA (Multi-Resolution Analysis) are discussed. These comparisons will help to improve the model’s rendering of wave impacts on their transportation medium, before extending the model’s range to ionospheric heights and properties.

How to cite: Jaffré, E., Bellisario, C., Keckhut, P., Froissart, P.-Y., Trémoulu, S., Chane-Ming, F., Simoneau, P., Hauchecorne, A., and Saillant, S.: Gravity wave model validation using nightglow emission observations for lower ionosphere disturbance modelling, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9840, https://doi.org/10.5194/egusphere-egu24-9840, 2024.

12:10–12:20
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EGU24-8908
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AS1.33
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On-site presentation
Jie Zeng, Gunter Stober, Wen Yi, Xianghui Xue, and Xiankang Dou

We present the first continuous observations of the three-dimensional winds in the mesosphere and lower thermosphere (MLT) of the northern hemisphere midlatitudes using the composite data from the first multistatic meteor radar network in China. Our continuous observations started in 2022. In the summer of 2023, typhoon Doksuri passed through China and resulted in intense rainfalls. To reveal the impact of the typhoon on the MLT region, we focus on the variability in the three-dimensional wind fields. The horizontal winds are retrieved using an improved Volume Velocity Processing (VVP) with coordinate transformation and non-linear constraints to minimize errors, and the vertical winds are retrieved from the horizontal divergence with magnitudes of less than 1m/s. We found that on the day when the typhoon passed through our meteor radar network, the horizontal winds strengthened southwest and contained small-scale waves, and the vertical winds showed no significant change.

How to cite: Zeng, J., Stober, G., Yi, W., Xue, X., and Dou, X.: 3-dimensional winds and impacts of the typhoon observed in the MLT region using the Chinese multistatic meteor radar network, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8908, https://doi.org/10.5194/egusphere-egu24-8908, 2024.

12:20–12:30
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EGU24-16288
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AS1.33
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ECS
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Highlight
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Virtual presentation
Wen Yi, Baozhu Zhou, Xianghui Xue, Jie Zeng, Guozhu Li, Njal Gulbrandsen, and Masaki Tsutsumi

In this study, the neutral density and horizontal wind observed by the four meteor radars, as well as the temperature measured by the Microwave Limb Sounder (MLS) onboard the Aura satellite are used to examine the response of neutral density, wind, and temperature in the MLT region to the stratospheric sudden warmings (SSWs) during 2005 to 2021 in the Northern Hemisphere. The four meteor radars include the Svalbard (78.3°N, 16°E) and Tromsø (69.6°N, 19.2°E) meteor radars at high latitudes and the Mohe (53.5°N, 122.3°E) and Beijing (40.3°N, 116.2°E) meteor radars at middle latitudes.

The superposed epoch analysis results indicate that 1) the neutral density over Svalbard and Tromsø at high latitude increased at the beginning of SSWs and decreased after the zonal mean stratospheric temperature reached the maximum. However, the neutral density over Mohe at midlatitudes decreased in neutral density at the beginning of SSW and increase after the zonal mean stratospheric temperature reached the maximum. 2) The zonal wind at high latitudes show a westward enhancement at the beginning of SSWs and then shows an eastward enhancement after the stratospheric temperature reaches maximum. However, the zonal wind at midlatitudes shows an opposite variation to at high latitudes, with an eastward enhancement at the onset and changing to westward enhancements after the stratospheric temperature maximum. The meridional winds at high and midlatitudes show a southward enhancement after the onset of SSW and then show a northward enhancement after the stratospheric temperature maximum. 3) In general, the temperature in the MLT region decreased throughout SSWs. However, as the latitudes decrease, the temperature cooling appears to lag a few days to the higher latitudes, and the degree of cooling will decrease relatively.

How to cite: Yi, W., Zhou, B., Xue, X., Zeng, J., Li, G., Gulbrandsen, N., and Tsutsumi, M.: Impact of Sudden Stratospheric Warmings on the Neutral Density, Temperature and Wind in the MLT region, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16288, https://doi.org/10.5194/egusphere-egu24-16288, 2024.

Posters on site: Mon, 15 Apr, 10:45–12:30 | Hall X5

The posters scheduled for on-site presentation are only visible in the poster hall in Vienna. If authors uploaded their presentation files, these files are linked from the abstracts below, but only on the day of the poster session.
Display time: Mon, 15 Apr 08:30–Mon, 15 Apr 12:30
Chairpersons: Alexis Le Pichon, Patrick Hupe, Gunter Stober
X5.20
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EGU24-8768
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AS1.33
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Guochun Shi, Hanli Liu, Witali Krochin, Masaki Tsutsumi, Njål Gulbrandsen, and Gunter Stober
We perform continuous ozone measurements above Ny-Ålesund, Svalbard (79 N, 12 E) with ground-based microwave radiometers GROMOS-C to explore the short-term and interannual variability of ozone in the polar middle atmosphere covering from 2015 to 2023. GROMOS-C measurements exhibit good agreement with MERRA-2 reanalysis and Aura-MLS satellite data. This work focuses on understanding the influence of highly altered dynamics of sudden stratospheric warming events on ozone variations in the Arctic middle atmosphere and investigating the potential role of ozone in connection to mesospheric tides reported for such events. We extract the mesospheric semi-diurnal tides (SDT) and diurnal tides (DT) from the zonal and meridional winds recorded by nearby meteor radars located at Svalbard (79N, 12E) and Tromsoe (69N,18.5E), and Sodankyla (67N, 26E) in the Arctic regions. Furthermore, these tidal observations are compared with simulations by the specified dynamics–whole atmosphere community climate model with ionosphere/thermosphere extension (SD-WACCM-X). Utilizing the middle atmospheric ozone observations by GROMOS-C and MLS, we investigate the impact of ozone variability attributed to sudden stratospheric warming events on tides in the Mesosphere and Lower Thermosphere (MLT). Our findings suggest a possible connection between alterations in middle atmospheric ozone and the underlying circulation, which subsequently influences tidal propagation up to the mesosphere. This indicates that, in conjunction with radiative forcing, these dynamics may play a significant role in driving mesospheric tides.
 
 

How to cite: Shi, G., Liu, H., Krochin, W., Tsutsumi, M., Gulbrandsen, N., and Stober, G.: Variability of middle atmospheric polar ozone and its effects on Arctic mesospheric tides, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8768, https://doi.org/10.5194/egusphere-egu24-8768, 2024.

X5.21
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EGU24-15128
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AS1.33
Gunter Stober, Sharon Vadas, Erich Becker, Alan Liu, Alexandre Kozlovsky, and Diego Janches and the HTHH Meteor radar and HIAMCM GW analysis team:

The Hunga Tonga-Hunga Ha‘apai (HTHH) volcanic eruption on 15th January 2022 was an unprecedented event and a unique opportunity to investigate volcanic-caused gravity waves (GW) and their global propagation. In this study, we have combined all the available meteor radar observations and data analysis to identify the HTHH GW in the observations. Our results are compared to model-based wind perturbations from HIAMCM of secondary waves that are forced by the GW model MESORAC using GOES-17 observations. Furthermore, we leverage the GW polarization relations to identify different wave features in the observations and perturbation runs with HIAMCM. There is a remarkable agreement in the observed phase speeds for the eastward and westward GW propagation between the observations and HIAMCM wind perturbations indicating that the mesospheric HTHH GW are explainable by secondary waves generated by breaking of the primary GWs from the eruption. We also shed some light on the importance of the quasi-2-day wave on the HTHH GW propagation.

How to cite: Stober, G., Vadas, S., Becker, E., Liu, A., Kozlovsky, A., and Janches, D. and the HTHH Meteor radar and HIAMCM GW analysis team:: Studying the global propagation of gravity waves generated by the Hunga Tonga-Hunga Ha‘apai volcanic eruption from meteor radar observations and the High-Altitude General Mechanistic Circulation Model, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15128, https://doi.org/10.5194/egusphere-egu24-15128, 2024.

X5.22
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EGU24-10208
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AS1.33
Christophe Bellisario, Pierre Simoneau, Sophie Derelle, Ewen Jaffré, Pierre-Yves Froissart, Philippe Keckhut, Alain Hauchecorne, Samuel Tremoulu, and Fabrice Chane-Ming

The infrared emission lines observed between 80 and 100 km known as nightglow allow the investigation of dynamic phenomena such as gravity waves with adapted cameras. In particular, the OH nightglow emission peaking at 87 km can be observed with short wave infrared InGaAs cameras and most of studies use these observations to investigate dynamics at this height. In this study, we briefly describe the methodology to assess the availability of nightglow observations at ground level depending on the spectral bands and the local atmospheric conditions. The impact of clouds on the spectral radiance propagation is estimated by the use of radiative transfer models. Sensitivity tests are completed on clouds characteristics, such as vertical width or the type of clouds. In addition, we integrate directional fluxes on the celestial dome to assess the level of radiance available at the ground level for night vision imaging. Statistical temporal comparisons are performed using available observations campaigns at Observatory of Haute-Provence (OHP) and at Maïdo Observatory.

How to cite: Bellisario, C., Simoneau, P., Derelle, S., Jaffré, E., Froissart, P.-Y., Keckhut, P., Hauchecorne, A., Tremoulu, S., and Chane-Ming, F.: Availability of nightglow ground observations for atmospheric dynamics monitoring, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10208, https://doi.org/10.5194/egusphere-egu24-10208, 2024.

X5.23
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EGU24-7854
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AS1.33
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ECS
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Highlight
Samuel Kristoffersen, Constantino Listowski, Robin Wing, Gerd Baumgarten, Sergey Khaykin, Alain Hauchecorne, Julien Vergoz, and Alexis Le Pichon

Infrasound signals are used to monitor various anthropogenic (explosions, wind farms etc.) and natural (earthquakes, volcanoes etc.) sources. In particular, infrasound is included as one of the four verification technologies used by the International Monitoring System (IMS) by the Comprehensive Test-Ban Treaty Organisation (CTBTO). To determine accurate source locations and estimate source energy, an accurate model of wind and temperature from the surface up to the lower thermosphere is necessary. Operational NWP products are necessary for routine infrasound monitoring activities. However, the use of a sponge layer above ~30 km, to insure stable NWP models, leads to biases in the middle atmosphere (MA), where the relevant infrasound waveguides for long-range propagation are found. For UA-ICON, the sponge layer is set much higher in the thermosphere. Therefore, the UA-ICON, which provides modelled atmospheric parameters up to 150 km (110 km sponge layer height), is relevant in this context. 
First, to assess ICON and IFS operational analysis products, comparisons to lidar observations are made. The main differences between both products were analysed with respect to winds and temperatures in the MA, and hence with respect to the infrasound guide prediction. Second, UA-ICON simulations were performed and the outputs were compared to ICON and IFS fields to demonstrate the increased wave activity above ~30 km with UA-ICON. The added value of UA-ICON with respect to ICON and IFS products for infrasound propagation simulations is discussed. The comparisons between the remote sensing instrumental results and the models will be presented, as well as comparisons between modelled and measured infrasound propagation. 

How to cite: Kristoffersen, S., Listowski, C., Wing, R., Baumgarten, G., Khaykin, S., Hauchecorne, A., Vergoz, J., and Le Pichon, A.: Simulating infrasound waveguides in the middle atmosphere with ICON and UA-ICON: comparison with the IFS and ground-based remote sensing, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7854, https://doi.org/10.5194/egusphere-egu24-7854, 2024.

X5.24
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EGU24-12783
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AS1.33
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Sven Peter Näsholm, Quentin Brissaud, Celine Marie Solberg, and Marouchka Froment

Seismic waves are a primary source of information for our understanding of Earth's internal structure and they provide important constraints on subsurface seismic-velocity properties. However, traditional inversion methods cannot be implemented in regions of limited seismic-station coverage, in particular on Venus due to its harsh surface conditions but also in remote Earth regions. This lack of seismic data greatly limits our understanding of Venus’ origin and evolution and Earth’s subsurface. A window of opportunity is offered by the mechanical coupling between the ground and its atmosphere, which enables the seismic energy to be transmitted into the atmosphere as low-frequency acoustic waves carrying information about the seismic source and the subsurface properties. While infrasound is traditionally recorded at ground-based stations, which suffers from the same in-situ deployment limitations as seismic stations, recent studies have demonstrated that balloon platforms can be used to monitor seismic activity from the atmosphere at a low operational cost. Balloon-borne seismology is a new dynamic field and this might be the only viable approach to investigate Venus’ interior. However, inversion methods for balloon-borne infrasound data are not well developed and the coupling between seismic and acoustic waves in realistic media is not fully understood. In this contribution, we will explore the feasibility of detecting seismically-generated infrasound waves on Venus and assess their potential for subsurface velocity inversions through full-waveform numerical simulations.

How to cite: Näsholm, S. P., Brissaud, Q., Solberg, C. M., and Froment, M.: Exploring the feasibility of detecting seismically-generated infrasound waves on Venus using balloon platforms, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12783, https://doi.org/10.5194/egusphere-egu24-12783, 2024.

X5.25
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EGU24-6063
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AS1.33
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ECS
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Pierre Letournel, Constantino Listowski, Marc Bocquet, Alexis Le Pichon, and Alban Farchi

Due to the lack of observations, Numerical Weather Prediction (NWP) models are poorly constrained in the Middle Atmosphere (MA ~10-90km) and thus significantly biased [1]. Infrasounds of oceanic origin (microbaroms) propagate across thousands of kilometers and integrate information on the MA dynamical state and particularly on winds. Thus, we investigate how to assess the performance of NWP models in the MA through simulations and global and continuous observations of microbaroms. 

Infrasound observations are processed using an adaptation of the MCML [2] algorithm to obtain the azimuthal distribution of microbarom amplitudes at the International Monitoring System Norwegian infrasound station I37NO. These observations are compared to simulations where modelled distribution account for the antenna response relative to MCML processing.

Simulations of microbaroms arrival are carried for the year 2021 by combining a microbarom source model [3] and two propagation methods: a semi-empirical law using a single atmospheric profile and Parabolic Equation (PE) range-dependent propagation simulation accounting for the 3D atmosphere. Yearly comparisons through an optimal transport metric using atmospheric specification from different atmospheric models highlight the limitations of the semi-empirical law for a NWP model performance evaluation.

Atmospheric models are thus assessed building on the PE propagation simulations and first conclusions on models relative performances are derived over specific periods of interest, including a sudden stratospheric warming. While the current work focuses on the evaluation of NWP models, it will also allow to define a method relying on microbarom observations to improve these models through Data Assimilation.

 


[1] Le Pichon, A., Assink, J. D., Heinrich, P., Blanc, E., Charlton-Perez, A., Lee, C. F., Keckhut, P., Hauchecorne, A., Rüfenacht, R., Kämpfer, N., et al. (2015), Comparison of co-located independent ground-based middle atmospheric wind and temperature measurements with numerical weather prediction models, J. Geophys. Res. Atmos., 120, 8318–8331, doi:10.1002/2015JD023273.

[2] B Poste, M Charbit, A Le Pichon, C Listowski, F Roueff, J Vergoz, The multichannel maximum-likelihood (MCML) method: a new approach for infrasound detection and wave parameter estimation, Geophysical Journal International, Volume 232, Issue 2, February 2023, Pag-es 1099–1112, https://doi.org/10.1093/gji/ggac377

[3] De Carlo, M., Accensi, M., Ardhuin, F., and Le Pichon, A.: ARROW (AtmospheRic InfRasound by Ocean Waves): a new real-time product for global ambient noise monitoring., EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-7564, https://doi.org/10.5194/egusphere-egu22-7564, 2022.

How to cite: Letournel, P., Listowski, C., Bocquet, M., Le Pichon, A., and Farchi, A.: Using an oceanic acoustic noise model to evaluate simulated atmospheric states, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6063, https://doi.org/10.5194/egusphere-egu24-6063, 2024.

X5.26
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EGU24-20574
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AS1.33
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ECS
Alice Janela Cameijo, Alexis Le Pichon, and Quentin Brissaud

Accurate modeling of infrasound transmission losses (TLs) is essential to assess the detection thresholds of the global International Monitoring System (IMS) infrasound network, quantify their spatial and temporal variations, and refine interpretations of signals generated by events of interest. Among the existing tools, the method based on parabolic equations resolution (PEs) enables TLs to be modeled finely, but its computational cost does not currently allow exploration of a large parameter space for real-time prediction, making it inapplicable for operational monitoring applications in the framework of the Comprehensive Test Ban Treaty (CTBT).

To reduce computation times, Brissaud et al. (2022) explored the potential of convolutional neural networks (CNNs) trained on a large set of regionally simulated wavefields (>1000 km distance from the source) to predict TLs with an error of 5 dB compared to PE simulations with negligible computation times ( 0.05 s). However, this new method shows both larger errors in upwind conditions, especially at low frequencies, and causal issues with winds at large distances from the source affecting ground TLs close to the source.

To reduce prediction errors, we introduce a new Deep Learning method, seeking to predict TLs from globally simulated effective sound velocity fields (>4000 km distance), based on a Convolutional Recurrent Neural Network (CRNN) capable of accounting the sequentiality of the propagation phenomenon. This tool can be used to compute global detectability maps of infrasound events in an operational context.

How to cite: Janela Cameijo, A., Le Pichon, A., and Brissaud, Q.: Deep learning methods for modeling infrasound transmission loss in the middle atmosphere, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20574, https://doi.org/10.5194/egusphere-egu24-20574, 2024.

X5.27
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EGU24-3345
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AS1.33
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Highlight
Thomas Farges, Sara Albert, Daniel Bowman, Gael Burgos, Olaf Gainville, Pierre Sochala, and Alexis Le Pichon

On 3 August 2021, Sandia launched a flotilla of four Heliotrope solar hot air balloons (Bowman et al., 2020) from Belen regional airport in New Mexico (USA) to coincide with the launch of the Boeing Starliner rocket. Three balloons were equipped with two Gem microphones (Anderson et al., 2018) spaced vertically from 30 to 100 m apart, depending on the balloon. The fourth balloon had two infraBSU microbarometers mounted in opposite polarity in order to suppress local interference. These Heliotrope balloons allow level flights between 15 and 25 km altitude for several hours from sunrise to sunset. The rocket launch was cancelled after the balloons were launched, but eight chemical explosions of between 45 and 135 kg TNT equivalent and a thunderstorm took place near the balloons in the first few hours of cruise. After characterizing the measurements of explosions on balloons and two ground seismic stations, we evaluate the performance of a Bayesian method for locating explosions, taking into account local meteorology and whether or not seismic measurements were included. Using acoustic measurements under balloon conditions alone, we highlight the importance of network geometry and propagation between the explosion and the sensors in the localization error. We then characterize the lightning that occurred in a single thunderstorm cell located between 10 and 40 km from three of the four balloons. Several lightning flashes are clearly identified (using the method proposed by Farges and Blanc (2010) for ground thunder measurements and Lamb et al. (2018) for first stratospheric balloon measurements of lightning) and located in 3D with the method validated from explosion measurements. These 3D locations are compared with the 3D thunder model defined by Lacroix et al. (2010) and with the 3D distribution of thunder sound power described by Bestard et al. (2023). Finally, as the storm lasted approximately 45 minutes, continuous thunder emissions occurred. We calculated the cross-correlation time between measurements made under one of the balloons at 30 m apart during this period. We can see a change in the relative arrival delay as the balloon moves away from the storm cell, which does not move over this period. This suggests propagation through the AtmoSOFAR channel as defined by Albert et al (2023).

SNL is managed and operated by NTESS under DOE NNSA contract DE-NA0003525.

 

 

How to cite: Farges, T., Albert, S., Bowman, D., Burgos, G., Gainville, O., Sochala, P., and Le Pichon, A.: Characterisation and localisation of lightning and explosions by a flotilla of stratospheric balloons, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3345, https://doi.org/10.5194/egusphere-egu24-3345, 2024.

X5.28
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EGU24-5622
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AS1.33
Daniela Ghica and Bogdan Antonescu

During thunderstorms in northern Romania, numerous infrasonic signals are emitted due to the process of lightning and thunder. Association between infrasound detections into 0.5 to 7 Hz frequency band and lightning flashes detected by the Arrival Time Difference lightning network (ATDnet) managed by the Met Office within 50 km from the BURARI infrasound station is systematically investigated. Statistical results are presented based on infrasound and lightning observations during summer months (June to August) from 2020 to 2022.

Assuming direct wave propagation path, infrasound detections can be successfully correlated with ATDnet lightning detections up to distances of 50 km from the infrasound array. Long-duration trains of frequent sharp spikes in the amplitude observed into infrasound recordings during thunderstorms are associated with lightning discharges. Acoustic signatures of lightning activity show short-lived disturbances with dominant frequency of approx. 3 Hz and amplitudes ranging from 0.01 up to about 0.5 Pa. In order to associate BURARI measurements with ATDnet detections, a relationship between infrasound time-of-arrival and time of discharge signals is applied. A maximum deviation of 10o between observed infrasound back-azimuth and back-azimuth of ATDnet detections is allowed.

For several cases (days with the largest number of lightnings), detection conditions of infrasound from lightning are detailed, and some characteristics are analyzed (e.g., amplitude, frequency, trace velocity and spectrograms in the frequency range from 0.5 to 10 Hz). Correlations with synoptic charts, regional lightning activity maps and electric field measurements could be performed.

How to cite: Ghica, D. and Antonescu, B.: Infrasound from lightning measured in northern Romania, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5622, https://doi.org/10.5194/egusphere-egu24-5622, 2024.

X5.29
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EGU24-8267
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AS1.33
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ECS
Marcell Pásztor, Tereza Šindelářová, Daniela Ghica, Bogdan Antonescu, Ulrike Mitterbauer, Alexander Liashchuk, Tamás Bozóki, and István Bondár

The Central and Eastern European Infrasound Network (CEEIN) has been operating since 2019 in a collaboration of Hungarian, Czech, Romanian, Austrian, and Ukrainian research institutes. The study aims to extend the process of categorisation of infrasound signals that has been previously applied to the Hungarian infrasound array (PSZI) to the other CEEIN stations. The method of associating infrasound signals with thunderstorms relies on correlating the detections both spatially and temporally to lighting data from the Worldwide Lightning Location Network (WWLLN), which is considered ground truth. As a result, over 30,000 infrasound detections were categorized as thunderstorm-originated in the period between 2019 and 2023. Based on the results, we analyse the capabilities of the CEEIN to detect thunderstorms.

How to cite: Pásztor, M., Šindelářová, T., Ghica, D., Antonescu, B., Mitterbauer, U., Liashchuk, A., Bozóki, T., and Bondár, I.: Categorisation of infrasound signals originated from thunderstorms using the Central and Eastern European Infrasound Network, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8267, https://doi.org/10.5194/egusphere-egu24-8267, 2024.

X5.30
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EGU24-18155
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AS1.33
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ECS
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Highlight
Rodrigo De Negri, Vincent Boulenger, Duccio Gheri, Patrick Hupe, Philippe Labazuy, Alexis Le Pichon, Emanuele Marchetti, Peter Näsholm, Pierrick Mialle, and Philippe Héreil

Volcanic explosive eruptions produce large amounts of low-frequency (<20 Hz) acoustic waves, called infrasound. Notably, infrasound waves experience minimal attenuation in the atmosphere and can propagate over hundreds to thousands of kilometers, being a valuable resource for remote monitoring of volcanic hazards. This is a core reason why the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) has been tasked with installing and operating the International Monitoring System (IMS) infrasound network, with 53 (of 60 planned) infrasound stations continuously recording to detect any nuclear explosion on Earth.

A software prototype for long-range volcanic eruption notification called VIS (Volcanic Information System) was developed within the Atmospheric dynamics Research InfraStructure in Europe (ARISE) project (FP7, H2020), in collaboration with the Toulouse Volcanic Ash Advisory Centre (VAAC). The VIS main goal is to detect volcanic eruptions at regional to global distances (15-250 km; >250 km) with sustained ash-columns and provide early warnings to mitigate the risk that eruptions pose to civil aviation. Additionally, it can reconstruct the chronology of eruptions, and provide volcanic source constraints (acoustic intensity, gas flow, etc.). The system is designed to integrate the IMS and national infrasound stations to gather all available infrasound detections in the area of interest. The detections rely on the Progressive Multi-Channel Correlation (PMCC) method, which separates coherent infrasound waves (detections) from noise. The VIS is based on the Infrasound Parameter (IP) criterion to establish when an eruption is in course, accounting for atmospheric propagation effects, detection persistency, and amplitude. An operational VIS demonstrator will be deployed on servers of the Observatoire de Physique du Globe de Clermont-Ferrand (OPGC, CNRS-INSU and University Clermont Auvergne) to monitor Mt. Etna and Stromboli in real-time using data from the Amiata infrasound array (AMT) operated by the University of Florence. The data products of the VIS demonstrator will be available through an application programming interface (API) hosted at OPGC, where also an archived catalogue of European volcano eruptions and the real-time data products for AMT will be hosted.

As part of the European Geo-INQUIRE project (HORIZON-INFRA-2021-SERV-01), the VIS will be integrated into the Thematic Core Service Volcano Observation (TCS-VO) of the European Plate Observing System (EPOS). Future developments will include integration into web services such as the HOTVOLC web-GIS interface (OPGC, CNRS-INSU) or the EPOS Data Portal.

How to cite: De Negri, R., Boulenger, V., Gheri, D., Hupe, P., Labazuy, P., Le Pichon, A., Marchetti, E., Näsholm, P., Mialle, P., and Héreil, P.: Recent Enhancements of the Volcanic Information System (VIS): An Infrasound-Based Long-Range Volcanic Eruption Notification System, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18155, https://doi.org/10.5194/egusphere-egu24-18155, 2024.

X5.31
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EGU24-7566
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AS1.33
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ECS
Patrick Hupe, Julien Vergoz, Christoph Pilger, and Alexis Le Pichon

On 7 February 2022, around 20:00 UTC, a large meteoroid entered the Earth’s atmosphere around 500 km off the coast of Namibia and South Africa. NASA’s Center for Near Earth Object Studies (CNEOS) lists the event as a fireball with an impact energy of 7 kt of TNT equivalent. This energy estimate is about 60 times lower than for the 2013 Chelyabinsk fireball (440 kt, CNEOS), which was broadly covered in the media. Infrasound measurements can be an independent information source for fireball events. Their infrasonic signatures originate from either the hypersonic trajectory, which emits ablational waves, or the explosive fragmentation, which emits a ballistic shock wave. Relations such as ReVelle’s law can even be used for energy release estimates based on infrasound detection parameters such as the dominant period of the signal. The analysis of infrasound data from the International Monitoring System (IMS) for the Comprehensive Nuclear-Test-Ban Treaty (CTBT) revealed that the Chelyabinsk fireball was the strongest event ever recorded by the IMS infrasound network at that time, when 20 out of 42 existing stations detected it. The second-strongest event of this type in the IMS era was the Bering Sea bolide that occurred on 18 December 2018 (49 kt, CNEOS), with a comparable portion of infrasound stations detecting it (25 out of 51, according to Pilger et al. 2019, doi: 10.3390/atmos11010083).

For the 2022 South Atlantic fireball, we have found signatures at 20 infrasound stations of the IMS, too, out of 53 stations certified nowadays. We further characterize the event using the infrasound observations, model the infrasound propagation between the elevated source and the arrays, and assess the detection capability to explain the large number of detecting stations. We also use the IMS data for estimating an energy release, and revisit previous strong events such as Chelyabinsk using state-of-the-art array processing methods and enhanced configurations. These comprise the Multi-Channel Maximum-Likelihood (MCML) method or the one-third-octave band configuration within the Progressive Multi-Channel Correlation (PMCC) method, respectively.

How to cite: Hupe, P., Vergoz, J., Pilger, C., and Le Pichon, A.: Characterizing the 2022 South Atlantic fireball using infrasound recordings of the International Monitoring System, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7566, https://doi.org/10.5194/egusphere-egu24-7566, 2024.

Posters virtual: Mon, 15 Apr, 14:00–15:45 | vHall X5

The posters scheduled for virtual presentation are visible in Gather.Town. Attendees are asked to meet the authors during the scheduled attendance time for live video chats. If authors uploaded their presentation files, these files are also linked from the abstracts below, but only on the day of the poster session. The button to access Gather.Town appears just before the time block starts.
Display time: Mon, 15 Apr 08:30–Mon, 15 Apr 18:00
Chairpersons: Alain Hauchecorne, Sven Peter Näsholm, Patrick Hupe
vX5.6
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EGU24-20771
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AS1.33
Elizabeth Silber

Very bright meteors, also known as fireballs and bolides, are produced when extraterrestrial objects larger than approximately 10 cm in diameter enter dense regions of the Earth’s atmosphere. Besides the luminous phenomenon, bolides also generate shock waves, which decay to low frequency acoustic waves or infrasound. Depending on initial conditions, atmospheric propagation paths, and the mode of shock production, infrasound emanating from a bolide can be detected by microbarometers hundreds and even thousands of kilometers away. Unlike other sensing modalities that might have geographic (e.g., inaccessible regions), time-of-day (e.g., optical) or other limitations, infrasound can be utilized continuously (day and night) on a global scale. Hence, infrasound can be leveraged towards detection and localization of bolides, as well as estimating their explosive yield. Bolide infrasound detections date back to the early 20th century. On June 30, 1908, an extraterrestrial object exploded over Tunguska, Siberia, generating low frequency acoustic waves that mark the first known instrumentally observed bolide infrasound. During the mid-20th century, ten large bolides were detected by infrasound stations meant for explosion monitoring. Since the mid-1990s, many more events have been detected via infrasound. However, characterization of bolides through infrasound is not without its challenges, mainly because no two bolide events are alike. Systematic studies and data fusion can be leveraged towards efforts to better constrain some key parameters.  

SNL is managed and operated by NTESS under DOE NNSA contract DE-NA0003525.

How to cite: Silber, E.: Infrasound as a tool for detection and characterization of bolides, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20771, https://doi.org/10.5194/egusphere-egu24-20771, 2024.

vX5.7
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EGU24-17591
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AS1.33
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ECS
Samuel Trémoulu, Fabrice Chane Ming, Sergey Khaykin, Mathieu Ratynski, Alain Hauchecorne, Philippe Keckhut, and Christophe Bellisario

The study investigates the vertical wave coupling from the Earth's surface to the middle atmosphere over the Maïdo Observatory at La Réunion (21°S, 55.5°E). Wind velocity and temperature profiles from the ground-based instruments, including the LiWind Doppler Rayleigh-Mie and Li1200 Rayleigh Lidars, in conjunction with other observations (radiosoundings, COSMIC-2 radio-occultation, SABER) and ERA5 reanalysis, are analyzed to characterize gravity waves (GW) and their vertical propagation during the period from November 20th to November 24th, 2023. Notably, a tropospheric subtropical westerly jet manifested above La Réunion during this period and jet instabilities contributed to enhance GW activity in the troposphere. Wavelet methods are employed for denoising purposes and for highlighting multiscale GW from raw wind and temperature profiles. In particular, our analysis reveals the existence of a GW with a 5-km vertical wavelength and approximately a 24-hour period, propagating upward from lower troposphere to the middle atmosphere above La Réunion’s Maïdo Observatory. Among others, the horizontal distribution of this structure surrounding La Réunion is examined using COSMIC-2 radio-occultation and SABER data. In addition, the ERA5 analysis also provides supporting evidence of such structures and GW filtering in the stratosphere.

How to cite: Trémoulu, S., Chane Ming, F., Khaykin, S., Ratynski, M., Hauchecorne, A., Keckhut, P., and Bellisario, C.: Unraveling Gravity Wave Coupling from Surface to Stratosphere above La Réunion's Maïdo Observatory (21°S, 55.5°E) from Doppler and Rayleigh lidar observations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17591, https://doi.org/10.5194/egusphere-egu24-17591, 2024.