AS1.13

EDI
Infrasound, acoustic-gravity waves, and atmospheric dynamics

The infrasound field, the science of low-frequency acoustic waves, has developed into a broad interdisciplinary field encompassing academic disciplines of geophysics and recent technical and scientific developments. The infrasound network of the International Monitoring Network (IMS) for nuclear test ban verification and regional cluster arrays deployed around the globe have demonstrated their capacity for detecting and locating most of the disturbances in the atmosphere. Infrasound is capable of traveling up to thermospheric altitudes and over enormous ranges, where its propagation is controlled by the wind and temperature structure. Recent studies point out new insights on quantitative relationships between observables and atmospheric characteristics, and therefore opening a new field for atmospheric remote sensing.

New studies using lidar, radar, microwave spectrometer and mesospheric airglow observations complemented by satellite measurements help to better determine the interaction between atmospheric layers from the ground to the mesosphere and the influence of atmospheric waves on the mean flow. It is expected that further developing multi-instruments platforms would improve gravity wave parameterizations and enlarge the science community interested by operational infrasound monitoring. The ARISE project, funded by the European Commission, coordinates such studies. It proposes to design a novel infrastructure that integrates different atmospheric observation networks to infer a new 3D image of the atmosphere from the ground to mesosphere. In a higher frequency range, this monitoring system also offers a unique opportunity to provide in near-real time continuous relevant information about natural hazards with high societal benefits, like large volcanic eruptions, surface earthquakes or meteorites.

We invite contributions on current studies on sensors, characterization of different sources and large scale atmospheric phenomena, characterization of phenomena which affect acoustic propagation, utilization of acoustic waves to probe the atmosphere, contribution of gravity and planetary waves to the atmospheric dynamics and the coupling of atmospheric layers. In the session, we will also consider the role that infrasound and acoustic-gravity waves play in the coupled Earth’s crust – ocean – atmosphere system and, in particular, in ionospheric manifestations of physical processes in the ocean and in the solid Earth.

Convener: Alexis Le Pichon | Co-conveners: Elisabeth Blanc, Läslo G. Evers, Oleg Godin, Alain Hauchecorne
vPICO presentations
| Mon, 26 Apr, 09:00–12:30 (CEST)

vPICO presentations: Mon, 26 Apr

Chairpersons: Alexis Le Pichon, Oleg Godin, Alain Hauchecorne
Infrasound monitoring and source characterization
09:00–09:05
09:05–09:07
|
EGU21-15858
thomas philippe and sylvain carre

CEA is operating the French segment of the International Monitoring System of the Comprehensive Test Ban Treaty (CTBT). Construction of IMS stations was started on the late 90’ and one last station was pending before completing commitment of France.

Taking into account experience learned over the years, design was thought to combine enhanced detection capability and robustness. It gives also the opportunity to improve out monitoring tools and technics.

Station run 9 sensors spread out on a deep forest in Guadeloupe; power is distributed with buried cable while data are received with optical fibre to a central facility from which frames are sent to the International Data Center to the CTBTO. Constructiion was carried out in 2019.

IS25 was certified by the PTS of the CTBTO in November 2020

How to cite: philippe, T. and carre, S.: Infrasound station IS25 of the International Monitoring System of the Comprehensive Test Ban Treaty : from design to certification, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-15858, https://doi.org/10.5194/egusphere-egu21-15858, 2021.

09:07–09:09
|
EGU21-15376
stephane denis, paul vincent, and Rouille Guillaume

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.

09:09–09:11
|
EGU21-15038
Elisabeth Blanc, Patrick Hupe, Bernd Kaifler, Natalie Kaifler, Alexis Le Pichon, Philippe Keckhut, and Alain Hauchecorne

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.

09:11–09:13
|
EGU21-12043
|
ECS
Marine De Carlo, Patrick Hupe, Alexis Le Pichon, Lars Ceranna, and Fabrice Ardhuin

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.

09:13–09:18
|
EGU21-1776
|
ECS
|
solicited
Ekaterina Vorobeva, Marine De Carlo, Patrick Espy, and Sven Peter Näsholm

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.

09:18–09:20
|
EGU21-14248
|
Highlight
Alexandr Smirnov, Marine De Carlo, Alexis Le Pichon, Eleonore Stutzmann, and Nikolai Shapiro

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.

09:20–09:22
|
EGU21-16247
|
ECS
|
Highlight
Olivier F.C. den Ouden, Pieter S.M. Smets, Jelle D. Assink, and Läslo G. Evers

A comparison is made between in-situ infrasound recordings in the microbarom band and simulations using a microbarom source model. The recordings are obtained by the 'Infrasound-Logger' (IL), a miniature sensor deployed as a biologger near the Crozet Islands in January 2020. The sensors provide barometric and differential pressure observations obtained directly above the sea surface. As the full wavefield consists of multiple spatially distributed sources, a method is introduced to appropriately account for all microbarom source contributions surrounding the IL. In this method, the modeled source field is coupled to a semi-empirical propagation model to take into account the propagation losses from source to receiver. Although the method relies on several assumptions, a good agreement can be observed: the reconstructed soundscape is found to be within +- 5 dB for 80% of the measurements in the microbarom band of 0.1-0.3 Hz. The reconstruction of microbarom soundscapes is essential for understanding the ambient infrasonic noise field and benefits several applications that include atmospheric remote sensing, natural hazard monitoring as well as verification of the Comprehensive Nuclear-Test-Ban Treaty (CTBT).

How to cite: den Ouden, O. F. C., Smets, P. S. M., Assink, J. D., and Evers, L. G.: A novel approach for the reconstruction of microbarom soundscapes, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-16247, https://doi.org/10.5194/egusphere-egu21-16247, 2021.

09:22–09:24
|
EGU21-7606
|
ECS
Artemii Novoselov, Florian Fuchs, Manfred Dorninger, and Goetz Bokelmann

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.

09:24–09:26
|
EGU21-6525
|
ECS
|
Highlight
Marcell Pásztor, Csenge Czanik, and István Bondár

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.

09:26–09:28
|
EGU21-8484
|
ECS
Brandow Neri and Lucas Barros

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.

09:28–09:30
|
EGU21-1366
Daniela Ghica

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.

09:30–09:32
|
EGU21-5191
Ulrike Mitterbauer and Daniela Ghica

The project ABC-MAUS is undertaken by a collaboration of the Austrian Ministry of Defense, Joanneum Research, the Austrian national weather and geophysical service Zentralanstalt für Meteorologie und Geodynamik (ZAMG), including the Austrian National Data Center (NDC), as well as the private company GIHMM. The aim is to develop a strategy of protection for chemical, biological, radiological and nuclear threads (CBRN) for the Austrian armed forces.

In the frame of the project, a mobile infrasound array was deployed together with seismic sensors to monitor the military training ground Allentsteig in Lower Austria. During one week a series of controlled explosions was recorded. Infrasound data was processed and analyzed by using a duo of infrasound detection-oriented software (DTK-GPMCC and DTK-DIVA, packaged into NDC-in-a-Box). The dataset contained not only local and regional data, but revealed as well long term sources and – after comparing the data with data from stations of the CEEIN (Central Eastern European Infrasound Network) – some global events. Those events were localized using data of the temporary deployed array and by observations collected by other stations of the CEEIN.

How to cite: Mitterbauer, U. and Ghica, D.: Performance of a mobile infrasound station in the framework of CEEIN , EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-5191, https://doi.org/10.5194/egusphere-egu21-5191, 2021.

09:32–09:34
|
EGU21-15036
Galyna Sokol, Vladyslav Kotlov, Victor Frolov, Volodymyr Syrenko, and Volodymyr Dudnikov

Acoustic fields of various types of radiation and power arise during the rocket’s movement in the atmosphere after the launch. One of the most topical studies here is the analysis and assessment of the infrasonic radiation levels and their impact on the health of the nearby settlements population and the spaceport maintenance personnel. Therefore, it is necessary to identify the features and determine the directions of acoustic radiation research based on existing ideas about the generation, propagation, and impact of infrasound.

The methodology for researching acoustic radiation during rocket movement includes identifying the primary sources of acoustic vibrations. That is vibrations from a working propulsion system, from the vibrating shell of the rocket case, turbulent vortices in the flow around the rocket case. And also the identification of acoustic vibrations secondary sources arising from the primary vibrations reflection from collisions with obstacles, for example, the launch pad surface type.

It is necessary to develop physical models of acoustic fields, the nature of which depends primarily on the type of acoustic sources.

These are the following models:

  • point radiation (monopoles);
  • analysis of acoustic fields generated in the environment by force acting on a rigid surface and characterized by the Lamb potential;
  • acoustic radiation and fields during vibrations of plates and shells of various shapes, lengths, and areas;
  • acoustic radiation during the movable environment and solid bodies interaction;
  • acoustic radiation at the jets outflow from nozzles;
  • excitation and propagation of acoustic vibrations inside gas and liquid cavities, taking into account the peculiarities of the shells’ structural schemes, the resonances identification;
  • monochromatic and pulsed radiation.

The next step is the creation of mathematical models designed to calculate the acoustic field characteristics (analytical methods, the use of Taylor and Fourier series, numerical programming methods). Mathematical dependences will make it possible to analyze the relationship between the acoustic radiation sources energy characteristics and the characteristics of their acoustic fields. It is important to calculate the acoustic radiation amplitude-frequency characteristics.

Experimental tests, the development of programs, and methods for measuring the acoustic vibration characteristics are important. At the same time, a list of equipment necessary for measuring acoustic characteristics (instruments, circuits, equipment) is created.

As a result of physical and mathematical analysis of acoustic vibrations sources, it is possible to develop active and passive methods of damping them. As well as giving recommendations for damping acoustic vibrations.

How to cite: Sokol, G., Kotlov, V., Frolov, V., Syrenko, V., and Dudnikov, V.: Some Aspects of Acoustic Emissions during the Launch of a Space Rocket in Research of Earth by Satellites, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-15036, https://doi.org/10.5194/egusphere-egu21-15036, 2021.

09:34–09:36
|
EGU21-266
|
ECS
Islam Hamama, Masa-yuki Yamamoto, and Noha Ismail Medhat

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.

09:36–09:38
|
EGU21-4772
Alexis Le Pichon, Emanuele Marchetti, Christoph Pilger, Lars Ceranna, Viviane Souty, Bruno Hernandez, and Constantino Listowski

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.

09:38–10:30
Break
Chairpersons: Elisabeth Blanc, Läslo G. Evers
Acoustic gravity-waves, atmospheric dynamics and climate change
11:00–11:02
|
EGU21-8343
|
ECS
|
Highlight
Antoine Turquet, Quentin Brissaud, Sven Peter Näsholm, Johan Kero, Tormod Kværna, Constantino Listowski, and Alexis Le Pichon

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.

11:02–11:04
|
EGU21-10958
Lucie Rolland, Edhah Munaibari, Florian Zedek, Pierre Sakic, Anthony Sladen, Carene Larmat, T. Dylan Mikesell, and Bertrand Delouis

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.

11:04–11:06
|
EGU21-4912
Karl Koch and Christoph Pilger

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.

11:06–11:08
|
EGU21-14813
Johan Kero, Daniel Bowman, and Eli Bird

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.

11:08–11:10
|
EGU21-1384
Ismael Vera Rodriguez, Sven Peter Näsholm, Quentin Brissaud, Antoine Turquet, and Alexis Le Pichon

Atmospheric reanalysis models rely on the assimilation of direct and indirect measurements of different properties of the atmosphere. A better representation of the upper stratosphere in these models, especially for winds, can contribute to enhanced numerical weather predictions on weekly to monthly timescales. Infrasound waves provide complementary information to characterize the middle atmosphere. This is particularly valuable above 30 km altitude where few other currently available technologies provide direct measurements, especially for the dynamics.

In the current work, we update ensemble-averaged ERA5 atmospheric models to become consistent with sets of infrasound array observations of travel-time, backazimuth, and apparent velocity. The atmosphere is simplified to a layered, time-invariant representation, which is considered valid for infrasound propagation at regional distances (< 400km). The optimization is achieved via a heuristic solver derived from particle swarm optimization. The solver minimizes a mixed l1-l2 cost function that measures the distance between the infrasound observations and their prediction based on ray tracing through the updated atmospheric model. When the array station is situated within the classical shadow-zone range from the source, the infrasound observations are assumed to be stratospheric reflections, and the reflection altitude is included as part of the model parameters to estimate. The problem is highly ill-posed, which we alleviate by bounding the temperature and wind profile solution space to a region in the vicinity of the members of the ERA5 ensemble with 137-level reanalysis model product. The profiles are also smoothed using a length of the smoothing operator empirically adapted to match the constraint provided by the observations. The performance of the method is demonstrated using observations of infrasound waves produced by explosions that happen regularly during August and September at the site of Hukkakero in Finland and detected at the array station ARCES located in northern Norway. The updated atmospheric model profiles require corrections that are more significant above the 30 km altitude to explain the infrasound observations. These results are consistent over the observations of multiple explosions.

How to cite: Vera Rodriguez, I., Näsholm, S. P., Brissaud, Q., Turquet, A., and Le Pichon, A.: Estimation of infrasound-consistent wind and temperature atmospheric profiles from model ensembles in North Scandinavia, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-1384, https://doi.org/10.5194/egusphere-egu21-1384, 2021.

11:10–11:12
|
EGU21-10628
|
ECS
Annie Zelias, Olaf Gainville, and François Coulouvrat

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.

11:12–11:14
|
EGU21-13738
|
ECS
Ross Alter, Michelle Swearingen, and Mihan McKenna

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.

11:14–11:16
|
EGU21-2755
|
ECS
Yuliya Kurdyaeva and Sergey Kshevetskii

     The use of experimental data on pressure variations on the Earth's surface makes possible to study the propagation of acoustic-gravity waves from the lower to the upper atmosphere. However, a question arises: how the pressure on the Earth's surface is related to meteorological processes and how significant inaccuracy is allowed when replacing tropospheric meteorological sources instead experimentally observed pressure fluctuations on the Earth's surface.

     The problem of wave propagation from a tropospheric heat source was analytically studied to resolve this issue. Based on general assumptions about the tropospheric source and its parameters, an estimate of the waves that could be generated by such source was made. The study showed that the generation of internal gravity waves by a heat source cannot occur without the generation of infrasonic waves by this source. Therefore, infrasonic waves must also be taken into account. The source of infrasonic waves was defined and it was shown that in terms of power it is approximately equal to the source of internal gravity waves. Despite this, the amplitude of the generated infrasonic waves is less than the amplitude of the gravity ones, due to the fact that the source frequency is less than the acoustic cutoff frequency.

     In the numerical study of this problem, model local thermal small-sized tropospheric sources of waves operating at different frequencies were studied. Pressure fluctuations at the Earth's surface from the studied model source are recorded and then used at the boundary surface to calculate the propagation of waves upward from pressure fluctuations. Comparison results of calculations directly from a tropospheric source operating at infrasonic frequencies and from recorded pressure fluctuations on the Earth's surface showed that the wave pattern above the source, created directly by the tropospheric source, and from pressure variations recorded on the Earth's surface, practically coincide. In the case when the tropospheric source operates at the frequencies of internal gravity waves, the general coincidence of the two wave patterns also takes place. However, the quality of this match is lower. This happens due both to the typical features of the propagation of the internal gravity waves themselves, and to the fact that during the operation of such a source, infrasonic waves are additionally generated.

     The reported study was funded by RFBR and Kaliningrad region according to the research project № 19-45-390005.

How to cite: Kurdyaeva, Y. and Kshevetskii, S.: Study of Propagation of Acoustic-Gravity Waves Generated by Tropospheric Heat Source, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-2755, https://doi.org/10.5194/egusphere-egu21-2755, 2021.

11:16–11:18
|
EGU21-9970
|
Highlight
Alain Hauchecorne, Chantal Claud, and Philippe Keckhut

Sudden Stratospheric Warming (SSW) is the most spectacular dynamic event occurring in the middle atmosphere. It can lead to a warming of the winter polar stratosphere by a few tens of K in one to two weeks and a reversal of the stratospheric circulation from wintertime prevailing westerly winds to easterly winds similar to summer conditions. This strong modification of the stratospheric circulation has consequences for several applications, including the modification of the stratospheric infrasound guide. Depending on the date of the SSW, the westerly circulation can be re-established if the SSW occurs in mid-winter or the summer easterly circulation can be definitively established if the SSW occurs in late winter. In the latter case it is called Final Warming (FW). Each year, it is possible to define the date of the FW as the date of the final inversion of the zonal wind at 60°N - 10 hPa . If the FW is associated with a strong peak of planetary wave activity and a rapid increase in polar temperature, it is classified as dynamic FW. If the transition to the easterly wind is smooth without planetary wave activity, the FW is classified as radiative.

The analysis of the ERA5 database, which has recently been extended to 1950 (71 years of data), allowed a statistical analysis of the evolution of the stratosphere in winter. The main conclusions of this study will be presented :

- the state of the polar vortex in a given month is anticorrelated with its state 2 to 3 months earlier. The beginning of winter is anticorrelated with mid-winter and mid-winter is anticorrelated with the end of winter;

- dynamic FWs occur early in the season (March - early April) and are associated with a strong positive polar temperature anomaly, while radiative FWs occur later (late April - early May) without a polar temperature anomaly;

- the summer stratosphere (polar temperature and zonal wind) keeps the memory of its state in April-May at the time of FW at least until July .

These results could help to improve medium-range weather forecasts in the Northern Hemisphere due to the strong dynamic coupling between the troposphere and stratosphere during SSW events.

How to cite: Hauchecorne, A., Claud, C., and Keckhut, P.: Final Sudden Stratospheric Warmings and the memory of the stratosphere, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-9970, https://doi.org/10.5194/egusphere-egu21-9970, 2021.

11:18–11:20
|
EGU21-14312
|
ECS
J. Federico Conte, Jorge Chau, Diego Janches, David Fritts, Alan Liu, Zishun Qiao, Jacobo Salvador, and José Hormaechea

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.

11:20–11:22
|
EGU21-5769
|
ECS
Pavel Inchin, Jonathan Snively, Matthew Zettergren, Yoshihiro Kaneko, and Attila Komjathy

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.

11:22–11:24
|
EGU21-4243
|
ECS
Tatiana Syrenova and Alexander Beletsky

Acoustic gravity waves (AGW) manifestations spread from the lower atmosphere to the upper layers due to processes such as orography, weather fronts, deep convection atmosphere, and vice versa, can form in the upper atmosphere during geomagnetic activity, receiving energy from the magnetosphere. These wave processes can be considered as a dynamic process that transfers energy between different atmospheric and latitudinal regions, therefore it is important to understand their basic parameters and behavior.

In this work, to study wave disturbances, we used the Keo Sentinel optical system data, designed to record the spatial pattern of the 630 nm emission intensity (emission height 180-300 km). The system is located at the Geophysical Observatory (GPO) of the ISTP SB RAS, near the Tory, Buryatiya, Russia (520 N, 1030 E, height 670 m). The  interference filter transmission half-width is ~ 2 nm. Sight direction - zenith, field of view 145 degrees, exposure time 30-60 s (http://atmos.iszf.irk.ru/ru/data/keo).

For the analysis, we chose data obtained on clear, moonless nights from 2014 to March 2019. The total number of nights selected for analysis was 71 (~ 491 hours). An algorithm for the wave events and their characteristics automatic identification from the optic data was developed and tested. The approbation was carried out on a data set previously processed manually [Syrenova, Beletsky, 2019]. A comparison was made with traveling ionospheric disturbances (TID) characteristics obtained from the ISTP SB RAS radio-physical complex data [Medvedev et al., 2012].

The main directions of wave disturbances propagation obtained with automatic optical system data processing - southward (~ 175º) and eastward (~ 90º) - are similar to the TID directions. From the radiophysical complex data, the TID distribution from North to South prevails, the most probable azimuth is ~ 135º during the day, and ~ 205º at night. The most probable values ​​of the wave disturbances propagation velocity obtained as a result of automatic processing are about 80 m/s. These values ​​also accept well with the TID values.

The main characteristics obtained using the data of the optical and radiophysical complexes agree with each other. Differences in the preferred propagation direction of the recorded wave structures from the KEO Sentinel data from the directions obtained with photometers at the same observation point [Tashchilin, 2010, Podlesny, 2018], probably, associated with different observation heights.

This work was supported by a grant from the Russian Foundation for Basic Research N19-35-90093.

How to cite: Syrenova, T. and Beletsky, A.: AGW manifestations in the Earth neutral atmosphere and ionosphere, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-4243, https://doi.org/10.5194/egusphere-egu21-4243, 2021.

11:24–11:29
|
EGU21-9191
|
solicited
Gunter Stober, Ales Kuchar, Dimitry Pokhotelov, Huixin Liu, Hanli Liu, Hauke Schmidt, Christoph Jacobi, Peter Brown, Diego Janches, Damian Murphy, Alexander Kozlovsky, Mark Lester, Evgenia Belova, and Johan Kero

There is a growing scientific interest to investigate the forcing from the middle atmosphere dynamics on the thermosphere and ionosphere. This forcing is driven by atmospheric waves at various temporal and spatial scales. In this study, we cross-compare the nudged models Ground-to-topside model of Atmosphere and Ionosphere for Aeronomy (GAIA) and Whole Atmosphere Community Climate Model Extended

Version (Specified dynamics) ( WACCM-X(SD)), a free-running version of Upper Atmosphere ICOsahedral Non-hydrostatic (ICON-UA) with six meteor radars located at conjugate polar and mid-latitudes. Mean winds, diurnal and semidiurnal tidal amplitudes and phases were obtained from the radar observations at the mesosphere and lower thermosphere (MLT) and compared to the GAIA, WACCM-X(SD), and ICON-UA data for similar locations applying a harmonized diagnostic.

Our results indicate that GAIA zonal and meridional winds show a good agreement to the meteor radars during the winter season on both hemispheres, whereas WACCM-X(SD) and ICON-UA seem to reproduce better the summer zonal wind reversal. However, the mean winds also exhibit some deviation in the seasonal characteristic concerning the meteor radar measurements, which are attributed to the gravity wave parameterizations implemented in the models. All three models tend to reflect the seasonality of diurnal tidal amplitudes, but show some dissimilarities in tidal phases. We also found systematic interhemispheric differences in the seasonal characteristic of semidiurnal amplitudes and phases. The free-running ICON-UA apparently shows most of these interhemispheric differences, whereas WACCM-X(SD) and GAIA trend to have better agreement of the semidiurnal tidal variability in the northern hemisphere.

How to cite: Stober, G., Kuchar, A., Pokhotelov, D., Liu, H., Liu, H., Schmidt, H., Jacobi, C., Brown, P., Janches, D., Murphy, D., Kozlovsky, A., Lester, M., Belova, E., and Kero, J.: Interhemispheric comparison of mesosphere/lower thermosphere winds from GAIA, WACCM-X and ICON-UA simulations and meteor radar observations at mid- and polar latitudes, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-9191, https://doi.org/10.5194/egusphere-egu21-9191, 2021.

11:29–11:31
|
EGU21-7863
|
Highlight
Gerd Baumgarten, J. Federico Conte, Jens Fiedler, Michael Gerding, and Franz-Josef Lübken

Noctilucent clouds (NLC) exist at an altitude of about 83 km during the summer season at middle and polar latitudes. They consist of icy particles that exist in the polar summer mesopause region where the atmosphere is about 100 K colder than expected from pure radiative forcing. Dynamical effects, for example the dissipation of gravity waves, play an important role in the global circulation finally leading to the cold summer mesopause region. Ever since the first reports on the occurrence of NLC in 1885 the observers noticed distinct structures in the clouds that are most often wave-like. However at times the wave field becomes seemingly chaotic.

State of the art lidar and camera observations of NLC allow studying small-scale structures of tens of meters in the vertical and horizontal direction. Given a high time resolution (about one second), the development of these structures is measured on temporal scales spanning the range from inertia gravity waves to acoustic gravity waves. We will show observations with the RMR-lidars at ALOMAR (Northern Norway at 69°N) and Kühlungsborn (54°N) as well as cameras located nearby these stations. Using these combined observations we study waves and their transition to turbulence.

How to cite: Baumgarten, G., Conte, J. F., Fiedler, J., Gerding, M., and Lübken, F.-J.: Waves at the edge of space revealed by noctilucent cloud observations using camera and lidar, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-7863, https://doi.org/10.5194/egusphere-egu21-7863, 2021.

11:31–11:36
|
EGU21-15025
|
solicited
|
Highlight
Jelle Assink

A global network of microbarometer arrays has been installed for the verification of the Comprehensive Nuclear-Test-Ban Treaty (CTBT) using infrasound. The microbarometers also measure pressure variations that are due to various meteorological phenomena, such as gravity waves, with a resolution that exceeds that of typical barometers. Moreover, the use of array technology allows for the estimation of wavefront parameters, which is information that can generally not be obtained from typical automatic weather stations.

The value of these high-resolution observations for the monitoring of extreme weather is discussed here, focusing on two recent extreme weather events in The Netherlands. Data from a dense observational network that includes lidar facilities and the Dutch microbarometer array network is compared to forecasts from global and regional weather forecast models to assess the forecast skill of the state-of-the-art weather models. The first-order agreement suggests that microbarometer arrays could provide valuable data for the development of next-generation weather forecast models. Such developments are useful for Early Warning Centers that report on severe weather outbreaks that can be disruptive for society and which are expected to occur more frequently in a changing climate.

This presentation demonstrates that the infrasound technology, as a civil and scientific application, could aid in the forecasting of extreme weather events that are predicted to occur more frequently in a changing climate.

How to cite: Assink, J.: Microbarometer arrays for the monitoring of extreme weather in a changing climate, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-15025, https://doi.org/10.5194/egusphere-egu21-15025, 2021.

11:36–12:30