AS1.13

In order to improve the confidence in the results of measurements carried out in the field, on-site metrology is a key step. With the medium-term objective of being able to deploy a portable metrology system on different infrasound stations, CEA-DAM has tested an innovative system for calibrating its infrasound sensors. The first tests were conducted in November 2019 and September 2020 as part of the installation and certification of the IMS IS25 infrasound station in Guadeloupe. A total of 20 microbarometers were qualified on site.
We present the equipments deployed, the methods used and the results of the measurements carried out. It appears that the preliminary results show a very good correspondence between the measurements performed in the field, under particular environmental conditions, and the measurements performed in the metrology laboratory. The method will be confronted to the metrology community within the framework of the European Infra-AUV project in 2022.

How to cite: denis, S., vincent, P., and Guillaume, R.: Innovative on-site infrasound metrology conducted in 2019 and 2020, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-15376, https://doi.org/10.5194/egusphere-egu21-15376, 2021.

The uncertainties in the infrasound technology arise from the middle atmospheric disturbances, which are partly underrepresented in the atmospheric models such as in the European Centre for Medium-Range Weather Forecasts (ECMWF) products used for infrasound propagation simulations. In the framework of the ARISE (Atmospheric dynamics Research InfraStructure in Europe) project, multi-instrument observations are performed to provide new data sets for model improvement and future assimilations. In an unexpected way, new observations using the autonomous CORAL lidar showed significant differences between ECMWF analysis fields and observations in Argentina in the period range between 0.1 and 10 days. The model underestimates the wave activity, especially in the summer. During the same season, the infrasound bulletins of the IS02 station in Argentina indicate the presence of two prevailing directions of the detections, which are not reflected by the simulations. Observations at the Haute Provence Observatory (OHP) are used for comparison in different geophysical conditions. The origin of the observed anomalies are discussed in term of planetary waves effect on the infrasound propagation.

How to cite: Blanc, E., Hupe, P., Kaifler, B., Kaifler, N., Le Pichon, A., Keckhut, P., and Hauchecorne, A.: Impact of planetary waves on infrasound propagation uncertainties, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-15038, https://doi.org/10.5194/egusphere-egu21-15038, 2021.

Between 0.1 and 0.6 Hz, the coherent ambient infrasound noise is dominated worldwide by signals, so-called microbaroms, originating from the ocean. With an energy peaking around 0.2 Hz, microbaroms are generated by second order non-linear interactions between wind-waves at the ocean surface and are able to propagate all around the globe through the stratosphere and thermosphere. Monitoring these signals allows characterizing the source activity and probing the properties of their propagation medium, the middle atmosphere. Here we present the first quantitative validation of global microbaroms modelling against worldwide observations. Modelling microbaroms at ground-based stations is a complex process that requires accounting for sea-wave modelling, infrasound generation from wave interactions, infrasound propagation over thousands of kilometers and infrasound detection at stations. In this study, this process was represented by three main parameters: a wave action model, a source model and an attenuation law through the atmosphere. The global modelling is run for two values of each parameter and the results are quantitatively compared with the global reference database of microbaroms detected by the International Monitoring System over seven years. This study demonstrates that the new source model improves the prediction rate of observations by around 20 percent points compared to existing reference models. The performance is enhanced when combining a wind-dependent attenuation and an ocean wave model that includes coastal reflection.

How to cite: De Carlo, M., Hupe, P., Le Pichon, A., Ceranna, L., and Ardhuin, F.: Validation of a general microbarom source model using global infrasound observations of the International Monitoring System, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-12043, https://doi.org/10.5194/egusphere-egu21-12043, 2021.

This study investigates a vespagram-based approach as a tool for multi-direction comparison between simulated microbarom soundscapes and infrasound data recorded at ground-based stations. The used microbarom radiation model takes into consideration both finite ocean-depth and the source radiation dependence on elevation and azimuth angles, while the effects of the atmospheric ducting from the source regions to the station are estimated using a semi-empirical attenuation law. The infrasound data recorded at the IS37 station in northern Norway during 2014-2019 are processed in the framework of the velocity spectrum analysis to generate vespagrams presenting signal power depending on time and back-azimuth direction. The analysis is performed for five frequency bands distributed between 0.1 and 0.6 Hz. The processed infrasound data and the modelled microbarom soundscapes are compared in three different aspects: i) azimuthal distribution of dominating signal, ii) signal amplitude and iii) ability to track atmospheric changes during extreme events such as sudden stratospheric warmings (SSW). The back-azimuth resolution between the vespagrams and the microbarom model output is harmonized by smoothing the modelled soundscapes along the back-azimuth axis with a kernel corresponding to the frequency-dependent array resolution. The time-dependent similarity between the model output and the processed infrasound data is estimated using the image processing approach of mean-square difference. The results reveal good agreement between the model and the infrasound data and demonstrate the ability of vespagrams to monitor the time-dependent microbaroms azimuth distribution, amplitude, and frequency on a seasonal scale, as well as changes during SSWs. The presented vespagram-based approach is computationally low-cost and can uncover microbarom source variability. There is also a potential for near-real-time diagnostics of atmospheric model products and microbarom radiation models, especially when applied to multiple stations, e.g. exploiting the CTBTO International Monitoring System network.

How to cite: Vorobeva, E., De Carlo, M., Espy, P., and Näsholm, S. P.: Vespagram-based approach for microbarom radiation and propagation model assessment using infrasound recordings, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-1776, https://doi.org/10.5194/egusphere-egu21-1776, 2021.

Signature of the ocean storms at the center of Eurasia are studied using data from Kazakhstani stations. Data from seismic and infrasound arrays that are part of the International Monitoring System of the Comprehensive Test Ban Treaty Organization are used, including PS23-Makanchy, AS058-Kurchatov, and IS31-Aktyubinsk. These data were amended with the local information acquired by the National Nuclear Center of Kazakhstan: seismic arrays ABKAR-Akbulak and KKAR-Karatau, and infrasound arrays KURIS-Kurchatov and MKIAR-Makanchy. Seismic and acoustic signals from ocean storms were detected using standardized correlation based method from 2014 to 2017. A seismo-acoustic source model has been developed to predict seismic and acoustic signals. WAVEWATCH3 data are used for the source model simulation. Microbaroms attenuation was calculated using vertical atmospheric profiles developed by the European Centre for Medium-Range Weather Forecasts. Microseism source parameters were corrected for the bathymetry effect. Afterward, actual and predicted microbarom and microseism parameters are compared and analyzed: data are compared between different arrays. The results show clear seasonal features in recorded microseisms and microbaroms indicating that the sources are of the same origin. Discrepancies are found for the predicted and observed microseism backazimuths. The results of this study combining microbarom and microseism observations reveal the strengths and weaknesses of seismic and acoustic methods while analyzing signals from strong storms, and lead to the conclusion that a fusion of two techniques brings qualitatively new results. In particular, it demonstrates its efficiency for locating a source of seismic noise using infrasound observations, predicting the source amplitude using microseismic observations, correcting seismic propagation anomalies due to heterogeneities in the propagation medium using accurate infrasound backazimuths, and inferring new observational constraints in the middle atmosphere using an enhanced description of the microbarom source. These findings are promising for a better description of the source (localization, intensity, spectral distribution) and coupling mechanisms of the ocean/atmosphere/land interfaces.

How to cite: Smirnov, A., De Carlo, M., Le Pichon, A., Stutzmann, E., and Shapiro, N.: Seismoacoustic signature of the ocean storms at the center of Eurasia, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-14248, https://doi.org/10.5194/egusphere-egu21-14248, 2021.

Lightning strokes create powerful wavefields of seismoacoustic nature, which we refer to as thunder. Unfortunately, even though bolts of lightning received much attention in such fields as physics of plasma and meteorology, less research was conducted to investigate the thunder itself.

A radio tower on the top of the Gaisberg mountain in Salzburg is permanently instrumented with electrical sensors able to record the current of lightning strokes hitting the tower’s top. In October 2020, observations of 5 thunder signals have been made using several one-component seismic sensors. At the same time, this tower is instrumented with a meteorological station, which allows us to model precisely the propagation of seismo-acoustic thunder signals from the above-mentioned lightnings.

These observations and modeling give insight into how thunder is created during the lightning stroke, which is an important milestone for seismo-acoustic observations of atmospheric events.

How to cite: Novoselov, A., Fuchs, F., Dorninger, M., and Bokelmann, G.: ThunderSeis: Seismic analysis of thunder signals recorded at the Gaisberg mountain, Austria, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-7606, https://doi.org/10.5194/egusphere-egu21-7606, 2021.

The infrasound array at Piszkés-tető, Hungary (PSZI) has been operational since May, 2017. Since then PSZI has collected hundreds of thousands detections. These include detections both from known and unknown sources. The categorisation of the detections would be important for future automation. The objective of this study is to identify and collect those detections that belong to local and regional storms and lightings. We present a methodology to identify storms by correlating lightning data from the Blitzortung database we consider as ground truth with the PMCC infrasound detections at PSZI. We also analyse the seasonal variations in the directions and distances of the detected storms.

How to cite: Pásztor, M., Czanik, C., and Bondár, I.: Exploiting infrasound detections to identify and track regional storms, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-6525, https://doi.org/10.5194/egusphere-egu21-6525, 2021.

Infrasound monitoring is one of the four technologies used by the International Monitoring System to verify compliance with the CTBT. Atmospheric and shallow underground nuclear explosions can generate infrasound waves that can be detected by the infrasound networks. Of the 60 infrasonic stations proposed by CTBT, 10 are located in South American countries and islands close to the continent. Because the latest nuclear tests were underground and on the Asian continent, the infrasound stations in South America did not detect them. However, there are several sources of infrasound signals detect by South American stations. This work aims to present a complete catalog of infrasound events detected in South America.

How to cite: Neri, B. and Barros, L.: Preliminary results of  South American infrasound monitoring, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-8484, https://doi.org/10.5194/egusphere-egu21-8484, 2021.

Two infrasound stations are currently in operation on the Romanian territory: IPLOR 4-element array of 0.6 km aperture, in the central part, and BURARI 6-element array of 0.7 km aperture, in the northern region.

Automatic processing of continuous data recorded by the two arrays has revealed many impulsive signals generated by repeating sources confined in certain directions, i.e., sonic booms induced by supersonic aircraft activity. The approximate origins of the infrasound found by cross bearing the detections of IPLOR and BURARI arrays are typically pointed to the military air bases located in Romania and across Europe and Near East region. In some cases, the observed azimuths need to be corrected for the deviating effects of zonal cross-winds as the direction of stratospheric winds changes seasonally.

The distances to the sources of sonic booms range from 140 km (Romania) to 2200 km (North Sea, Northern Norway, Germany, France, Ukraine-Russia border, Aegean Sea, Turkey etc.). The signal characteristics varies when time and spatial distance increase: from short-spiked to long-pulsed shape, from higher amplitudes (1 Pa) to lower ones (0.01 Pa). In case of short-range propagation, high frequencies (above 1 Hz) predominate, while for long-range propagation, the lower frequency drops below 1 Hz and higher frequency components are attenuated.

How to cite: Ghica, D.: Recording sonic booms with the Romanian infrasound arrays, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-1366, https://doi.org/10.5194/egusphere-egu21-1366, 2021.

Chemical explosions generate shockwaves which can be recorded at far distant with infrasound sensors. Infrasound propagation and energy of the explosion are main factors which control the infrasonic wave arrivals. In this study, a China explosion which happened on 22 March 2019, Biuret explosion on 4 August 2020, and the explosion of MOMO-2 rocket failure during the launching process will be investigated. The infrasound data sets of these explosions are extracted from IMS infrasound stations and KUT infrasound sensors which are distributed all over Japan.

The explosions had different propagation conditions which can be simulated using ray tracing and parabolic equation numerical methods, furthermore the transmission losses can be estimated in order to determine the yield energy in TNT-equivalent of each explosion, moreover the severe surface damages were identified by using InSAR techniques which can be classified according to the interferometric coherency.

In conclusion, the integration between the infrasound technique and InSAR showed the safety zone which should be taken in account for any chemical factories or rocket launch sites.

How to cite: Hamama, I., Yamamoto, M., and Medhat, N. I.: Evaluation of the Chemical Explosions Impact using Infrasound and InSAR Analysis, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-266, https://doi.org/10.5194/egusphere-egu21-266, 2021.

Stromboli volcano is well known for its persistent explosive activity, with hundreds of explosions every day ejecting ash and scoria up to heights of several tens/few hundreds of meters. Such a mild activity is however punctuated by lava flows and major/paroxysmal explosions, that represent a much larger hazard. On July 3rd and August 28th 2019, two paroxysmal explosions occurred at Stromboli, generating an eruptive column that quickly raised up to 5 km above the sea level. The Toulouse Volcanic Ash Advisory Center (VAAC) emitted an advisory to the civil aviation with a two-hour delay. The various processes of this event were monitored near and far field by infrasonic arrays up to distance of 3,500 km and by the Italian national seismic network at range of hundreds of kilometres. Using state-of-the-art propagation modeling, we aim at identifying the various seismic and infrasound phases of the event to better characterize the volcanic source. We highlight the need for the integration of the global infrasound International Monitoring System (IMS) network with local and regional infrasound arrays capable of providing a timely early warning to VAACs. This study opens new perspectives in volcano monitoring for hazard assessment and could represent, in the future, an efficient tool in supporting VAACs activity.

How to cite: Le Pichon, A., Marchetti, E., Pilger, C., Ceranna, L., Souty, V., Hernandez, B., and Listowski, C.: Seismo-acoustic characterization of the 2019 Stromboli volcano paroxysm events, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-4772, https://doi.org/10.5194/egusphere-egu21-4772, 2021.

An earthquake happened in 18 May 2020 early morning in the Kiruna underground iron ore mine, Northern Sweden having a magnitude Mw 4.9. Following the earthquake, the mine was immediately evacuated because of the risk of aftershocks. This event is the largest mining-induced earthquake that has ever taken place in Scandinavia and it produced signals recorded by three infrasound arrays at distances of 7 km (KRIS, Sweden), 155 km (IS37, Norway) and 286 km (ARCI, Norway). We explore seismo-acoustic features of this event recorded in near and far-field. This procedure allows us to track how the signal propagated in the solid earth until the seismometers located at various distances or transmitted to the atmosphere and propagated further to the infrasound stations. Our study also provides a detailed comparison between observed and predicted wave front characteristics at the arrays. We conduct a comparison of amplitude corrected for propagation effect versus magnitude and ground shaking amplitude. These results show that this mine-quake having “unconventional” source mechanism generated infrasound recorded up to ~300 km and provided ground shaking information as well as local amplification caused by topographic and geological features.

How to cite: Turquet, A., Brissaud, Q., Näsholm, S. P., Kero, J., Kværna, T., Listowski, C., and Le Pichon, A.: Near and far-field seismo-acoustic analysis of mb 4.9 mining induced earthquake nearby Kiruna, Sweden, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-8343, https://doi.org/10.5194/egusphere-egu21-8343, 2021.

The third-largest earthquake of this 21st century ruptured the Andes subduction zone offshore of the Maule region in central Chile on 27 February 2010, in the middle of the night (3:35 am local time). This huge event triggered strong and destructive seismic motions accompanied by a devastating local tsunami and a significant transpacific tsunami. We investigate the impact of this earthquake on the ionosphere using Global Positioning System (GPS) satellites and other Global Navigation Satellite System (GNSS) data. Investigations related to ionospheric disturbances induced by mega-earthquakes accelerated with the Mw9.0 Tohoku earthquake of March 2011. The worldwide GNSS network, including the exceptionally dense Japanese GNSS network, observed a complex ionospheric response. With a better understanding of the physical mechanisms behind it and a more exhaustive data collection, we revisit the ionospheric wavefield triggered by the Mw8.8 Chile earthquake and tsunami.

When a large underwater earthquake occurs, the sudden shaking of an extended region of the sea-floor immediately transfers energy to the water column and the air above through an efficient solid-ocean-atmosphere coupling mechanism. The earthquake at depth thus excites seismic and tsunami waves in the ocean and acoustic-gravity waves in the atmosphere. In the lower frequency range (< 20 mHz), these atmospheric waves can propagate to the upper atmosphere, which shakes the ionosphere. During propagation in the rarefying atmosphere, the wave amplitude drastically increases by about four orders of magnitude. Typically, a tsunami with a height of the order of a meter in an open ocean puts the ionosphere into motion with peak displacement exceeding a kilometer at about 200 km of altitude. The shaken charged particles of the ionosphere plasma eventually induce fluctuations of propagation delays in radio signals, such as those emitted by GPS and GNSS satellites. We convert GNSS measurements into Total Electron Content (TEC) variations to study the ionospheric imprint.

We revisit the Maule earthquake with an in-depth analysis of the TEC data derived from a worldwide collection of GNSS records. We also compare the observed ionospheric responses to ground or ocean motions derived from high-frequency GNSS receiver data recorded onshore and offshore. Doing so, we further characterize the filtering effect of the atmosphere on acoustic-gravity waves driven from the Earth’s surface. Finally, we use numerical tools specifically developed to investigate the complex seismo-ionospheric wavefield triggered by large seismic ruptures. We focus on the resonant part of the seismo-acoustic response and the tsunami-induced ionospheric response and link them to waveguides in the solid-ocean-atmosphere system. This revisit intends ultimately to shed new and independent light on the 2010 Maule mega-earthquake rupture itself.

How to cite: Rolland, L., Munaibari, E., Zedek, F., Sakic, P., Sladen, A., Larmat, C., Mikesell, T. D., and Delouis, B.: Worldwide GNSS ionospheric response of the magnitude 8.8 2010 Chilean earthquake and tsunami: a revisit, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-10958, https://doi.org/10.5194/egusphere-egu21-10958, 2021.

From the more than 160 tests of the ARIANE-5 main engine carried out by the German Aerospace Center (DLR) facility near Heilbronn, Germany, a large overall portion was detected at IMS infrasound station IS26 in the Bavarian forest. Located at a distance of about 320 km in an easterly direction (99° east-southeast from North) these observations were mostly made in the winter season between October and April with a detection rate of more than 70% , as stratospheric winds favor infrasound propagating through the atmosphere within the stratospheric duct. Only two exceptions were found for the summer season when stratospheric ducting is not predicted neither by climatologies nor the applied weather prediction models, due to a reversal of the middle atmosphere wind pattern.

Numerical weather prediction models for summer and winter seasons, or times with detections or non-detections were compared. It is then found that these models differ significantly in the sound speed profiles producing either a strong stratospheric duct for altitudes between 30 and 60 km in the case of detection, i.e. in winter months – or a lack thereof inhibiting regional sound propagation in summer months. It is of course reflected by the effective sound speed ratio, mostly exceeding a value of 1 for detections and less than 1 for non-detections. A significant portion of profiles representing non-detections, however, exhibit a sound speed profile that should enable infrasound signal observations. These cases are analyzed in detail to identify which fine structures within the sound speed profiles could explain the lack of observations.

How to cite: Koch, K. and Pilger, C.: Insights into the atmospheric state through observations of infrasound from a ground-truth source at regional distance, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-4912, https://doi.org/10.5194/egusphere-egu21-4912, 2021.

The temperature and wind structure of the lower atmosphere creates an "acoustic shadow", where acoustic propagation is not expected to occur from a ground based source. This region begins several tens of kilometers from the source and typically ends between one hundred and two hundred kilometers range in the downwind direction of the stratospheric jet. Ground microbarometers still occasionally record acoustic arrivals in this zone due to tropospheric waveguides and/or scattering off of stratospheric structure not accounted for in atmospheric models. However, the properties of these signals in the lower stratosphere (above the tropospheric duct) is unknown, because they have never been previously observed on sensors at these altitudes. Here we present a set of acoustic arrivals from ground explosions recorded on balloons in the lower stratosphere during the mini-BOOSTER campaign in Sweden. Although some of the balloons were in the shadow zone, they still recorded a variety of waveforms from each event. Dual payloads on tethers show that the acoustic waves came from below in these instances. We discuss the provenance of these signals and implications for acoustic transmission in regions where geometric ray theory predicts their absence.

How to cite: Kero, J., Bowman, D., and Bird, E.: Infrasound transmission in the "shadow zone" observed on balloons in the lower stratosphere, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-14813, https://doi.org/10.5194/egusphere-egu21-14813, 2021.

The International Monitoring System (IMS) network of the Comprehensive nuclear-Test-Ban Treaty (CTBT) detects powerful natural and artificial infrasonic sources. One of these sources are meteorites which produce multi-arrival pressure signatures similar to explosion onces. Long range sonic boom modeling allows to distinguish these sources from one another. Our documented case is the Carancas meteorite that impacted the ground in Peru on September 15th, 2007, near the IMS infrasound station I08BO. Since this station is located within the shadow zone, classical ray tracing cannot be used to capture the characteristics of the recorded arrivals. Analytic continuation into complex plane of emission parameters of the ray tracing method allows to analyse the propagation in shadow zone for fully three dimensional problems. Contribution of complex ray ordinary differential equations integration and optimisation algorithm allows to compute complex eigenrays. Simulated infrasound wave arrival times, azimuths and apparent velocities at the station are compared with Carancas records.

How to cite: Zelias, A., Gainville, O., and Coulouvrat, F.: On the use of complex rays to analyse the sonic boom of the Carancas meteorite at I08BO station located into shadow zone, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-10628, https://doi.org/10.5194/egusphere-egu21-10628, 2021.

Infrasound can propagate over a variety of spatiotemporal ranges and is therefore affected by spatiotemporally diverse atmospheric conditions.  However, studies of the influence of meteorology on infrasound propagation have historically utilized weather data that rely on point sources or coarser spatiotemporal resolutions, which often gloss over the effects of mesoscale meteorological phenomena.  In light of this knowledge gap, this study examines the influence of mesoscale meteorological features on infrasound propagation on local and regional scales.  To accomplish this task, output from simulations using the Weather Research and Forecasting (WRF) meteorological model is fed into an infrasound propagation model to generate infrasound predictions using realistic meteorological conditions.  The WRF simulations covered a range of horizontal resolutions – from 1 to 15 km – enabling an analysis of the sensitivity of the infrasound predictions to the horizontal resolution of the WRF output.  The main result is that convective precipitation events can appreciably alter the transmission loss patterns emanating from infrasonic sources, which is especially evident at finer horizontal resolutions.  This demonstrates that high-resolution weather data may be necessary to correctly simulate local to regional infrasound propagation, especially within warm-season, convective environments.

(This work was funded by the Assistant Secretary of the Army for Acquisition, Logistics, and Technology [ASA{ALT}] under 0602784/T40/46 and 0602146/AR9/01.) 

Approved for public release: distribution is unlimited.

How to cite: Alter, R., Swearingen, M., and McKenna, M.: The influence of mesoscale atmospheric convection on local and regional infrasound propagation, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-13738, https://doi.org/10.5194/egusphere-egu21-13738, 2021.

The middle atmosphere over the southern Andes is known as one of the most dynamically active regions in the world. Previous studies have investigated wave dynamics at mesosphere and lower thermosphere (MLT) altitudes within this region, but only a handful of them have made use of continuous measurements provided by specular meteor radars (SMRs). Furthermore, it was only until recently that MLT horizontal wind gradients were estimated for the first time using a multistatic SMR network located in southern Patagonia. By observing larger amounts of meteors from different viewing angles, multistatic SMRs allow estimating not only more reliable momentum fluxes, but also parameters such us relative vorticity. In this work, we explore and compare MLT wave dynamics at low and middle latitudes around the Andes Mountain range. For this purpose, we investigate mean momentum fluxes and horizontal wind gradients obtained using four multistatic SMR networks: SIMONe Peru (12° S), CONDOR (30° S), SIMONe Argentina (50° S) and MMARIA-SAAMER (54° S).

How to cite: Conte, J. F., Chau, J., Janches, D., Fritts, D., Liu, A., Qiao, Z., Salvador, J., and Hormaechea, J.: Exploring MLT momentum fluxes and horizontal wind gradients over the Andes at four different latitudinal sectors using multistatic configurations, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-14312, https://doi.org/10.5194/egusphere-egu21-14312, 2021.

Recent studies have shown that upper atmospheric observations can be used to examine the properties of acoustic and gravity waves (AGWs) induced by natural hazards (NHs), including earthquakes and tsunamis (e.g., Komjathy et al., Radio Sci., 51, 2016). In addition to rapid processing, analysis, and retrieval of the AGW signals in data, the need remains to investigate a broad parameter space of atmospheric and ionospheric state observables for the robust constraint of coupled and nonlinear processes. Here, we present several earthquake/tsunami-atmosphere-ionosphere case studies that demonstrate the possibility to detect AGWs and constrain the characteristics of their sources. Direct numerical simulations of the triggering and wave dynamical processes, from Earth's interior to the exobase, are carried out based on coupled forward seismic wave and tsunami propagation models and our state-of-the-art nonlinear neutral atmosphere and ionosphere models MAGIC and GEMINI (Zettergren and Snively, JGR, 120, 2015).

We first demonstrate that ionospheric plasma responses to AGWs from large earthquakes include information about rupture evolutions, providing another independent dataset for the investigation of faulting processes (Inchin et al., JGR, 125, 4, 2020). At the same time, we highlight that remote sensing observables, such as total electron content (TEC), can be insensitive to some specifics of the rupturing process (and thus characteristics of induced AGWs) due to their integrated nature or inefficient geometry of observations to uncover those specifics, and should be used accordingly and with consideration of their geometry. Likewise, we demonstrate that ground-level magnetometer observations are readily sensitive to magnetic field disturbances from ionospheric dynamo effects, induced by coseismic AGWs generated over epicentral areas. These are readily measured at low cost, may also be incorporated to complement the analysis of earthquake-atmosphere-ionosphere coupled processes. Next, we show that in addition to ionospheric plasma responses, mesopause airglow (MA) transient imprints of coseismic and tsunamigenic AGWs are readily detectable with modern ground- and space-based imagers. We demonstrate that AGW-driven fluctuations in the MA, generated over near-epicentral areas, may be readily detectable 6 minutes after the earthquake, providing an important and independent data source to supplement early-warning systems, additionally uncovering specifics of rupturing processes (Inchin et al., JGR, 125, 6, 2020). The amplitudes of tsunamigenic AGWs and related fluctuations in MA closely follow the dynamics of the tsunamis, uncovering their spatial and temporal evolutions (Inchin et al., JGR, 125, 12, 2020). In summary, comprehensive dynamical simulations reveal subsequent observable features of surface to atmosphere-ionosphere coupling, and new opportunities to diagnose hazard processes.

Field of simulated (a) absolute maximum vertical ocean surface velocities and (b) absolute maximum hydroxyl temperature perturbations. 

How to cite: Inchin, P., Snively, J., Zettergren, M., Kaneko, Y., and Komjathy, A.: Modeling of upper atmospheric responses to acoustic-gravity waves generated by earthquakes and tsunamis, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-5769, https://doi.org/10.5194/egusphere-egu21-5769, 2021.