Systematic characterization of coherent infrasound detection is important for quantifying the recording environment of each station which influence the detection probability of specific signals of interest. We present results of global coherent infrasound measured at IMS infrasound stations and its correlation with atmospheric dynamics. The processed database covers the time period from 2005...
Infrasonic energy is known to propagate into the upper atmosphere before returning to the ground surface. A number of researchers have shown that transient infrasonic signals observed at spatially separated points can be used to estimate characteristics of the atmospheric winds. A statistical framework will be presented to demonstrate the extension of such methods to continuous infrasonic...
As a part of the Source Physics Experiment (SPE) site characterization and explosive test series, we developed and deployed an airborne octocopter infrasound platform. Traditionally, infrasound data is collected with sensors and arrays that are installed on the ground. For most applications this is sufficient but can be limiting when observing non-isotropic sources, such as underground...
In order to understand regional infrasound sources and improve the accuracy of the discrimination for the nuclear test, the development of the infrasound monitoring system with a low-cost and compact size has been started and the portable infrasound observation kit by using the nano-resolution digital quarts resonator sensor (Paroscientific, Inc., USA) was developed in 2011. Until now, in...
The 28th October 2014 in Wallops Flight Facility, orbital’s Antares launch vehicle failed and heavily exploded onto the launch pad area. At that time, the US transportable array of more than 200 operating stations (all equipped with microbarometers), was located on the east coast of the US and surrounded the accident. A large amount and variety of infrasound phases were observed at some...
Remote event detection and location using infrasound requires high quality temporal and spatial atmospheric models. Large industrial blasts and military explosions are tightly constrained in time and space using seismic data and can generate infrasound recorded both regionally and globally. The most useful seismo-acoustic sources are repeating sources with relatively frequent explosions,...
A realistic modeling of infrasound propagation is necessary for acoustic event detection and location, and for evaluating models of the state of the atmosphere. Infrasound arrivals are typically predicted using ray-tracing although full-waveform modeling is frequently necessary. The reflectivity method generates synthetic seismograms for point sources in a layered medium. For an accidental...
Explosive volcanic eruptions are among the most powerful sources of infrasound observed on earth, with recordings routinely made at ranges of hundreds to thousands of kilometers. These eruptions can also inject large volumes of ash into heavily travelled aviation corridors, thus posing a significant societal and economic hazard. Detecting and counting the global occurrence of explosive...
Accurate prediction of Sudden Stratospheric Warming (SSW) events is important for the performance of numerical weather prediction due to significant stratosphere--troposphere coupling. In this study, for the first time middle atmospheric numerical weather forecasts are evaluated using infrasound. A year of near continuous infrasound from Mt. Tolbachik (Kamchatka, Russian Federation) is...
Starting from 1957, Baikonur cosmodrome located in Central Kazakhstan launches rockets on a regular basis. The flight traces pass over the territory of Kazakhstan where the infrasound and seismic stations of KZNET network are installed. KNDC Data Centre conducts detailed analysis of seismic and acoustic records of events of different nature round-the-clock; among them there are some associated...
The IDC collects waveforms from a global network of infrasound sensors maintained by the IMS, and automatically detects signal onsets and associates them to form event hypotheses. However, a large number of signal onsets are due to local clutter sources such as microbaroms (from standing waves in the oceans), waterfalls, dams, gas flares, surf (ocean breaking waves) etc. These sources are...
This work is devoted to the signal processing algorithm developed for the on-site calibration of infrasound stations in accordance with the draft IMS operational manual. This algorithm is based on the comparison of the spectral contents between the sensor under test and a known reference sensor. However because the large signal variability, mainly due to the wind effects, the requirements are...
Infrasound sensor and array networks on the ground and aloft permit acoustic remote sensing for diverse natural and man-made events. This paper discusses the evolution of monitoring systems for both natural and man made hazards, including (but not limited to) volcanoes, earthquakes, tsunamis, typhoons, explosions, and industrial accidents.
Infrasound re-entered automatic processing at the International Data Center, Vienna, on 11th February, 2010. This presentation provides a review of the infrasound arrivals that have been incorporated into the automatically generated Standard Event Lists (SEL's) and the analyst-reviewed Reviewed Event Bulletin (REB) over the past five years. The analysis focuses upon events in western Eurasia;...
While long-range infrasound propagation modeling is a useful tool in geophysics and nuclear treaty verification, the inherent unpredictability of subgrid-scale atmosphere dynamics results in a poorly constrained propagation medium. This work reports on the project FLOWS (Fast Low Order Wave Simulation) that begun in 2013 and whose aim is to reformulate the problem in a probabilistic framework...
We apply infrasound pipeline processing algorithms to multiple years of International Monitoring System infrasound data. The results are summarized to identify trends in detection bulletins at each IMS infrasound array. Automatically formed events are compared with the CTBTO Reviewed Event Bulletin for the same time period. By identifying both false positives and false negatives, we identify...
The coupling between gravity waves and the turbulence-generated atmospheric noise has been studied from the beginning of 1970:ies. The uncorrelated atmospheric noise, normally considered as an obstacle when detecting weak infrasonic signals, may be, studying its envelope, used to extract gravity waves passing through the turbulent medium. Dimensions of arrays of the Swedish-Finnish Infrasound...
The collection of usable infrasound station data is a pragmatic performance requirement. Infrasound array I39PW, Palau, is located near the Asian-Pacific Ring of Fire and within the Northwestern Pacific typhoon basin. These natural source regions provide abundant ambient signals for assessing station performance and streamlining processing routines. The University of Hawaii Infrasound...
The IDC advances its methods and continuously improves its automatic system for the infrasound technology. The IDC focuses on enhancing the automatic system for the identification of valid signals and the optimization of the network detection threshold by identifying ways to refine signal characterization methodology and association criteria. An objective of this study is to reduce the number...
The problem of identification of infrasonic signals with frequency (0.002-0.02 Hz) was studied. Such infrasonic signals can be obtained from atmospheric storms. Signals amplitudes comparable with a noise. The data obtained from IMS station IS 43 were analyzed. Two identification methods of infrasonic signals were used. The first based on the Fourier and morphological analysis and the second...
Together with the guidance of the PTS 2014-2017 Midterm Strategy, IMS Operational Manuals and historical experience throughout the IMS, IMS/ED has begun an earnest and well planned effort to improve the quality of future equipment and services support contracts. In order to benefit IMS stations, targeted engineering contracts include intra site communications, station power systems,...
Some data on a high-frequency infrasound recorded within a range of 2--16 Hz ("voice of the sea") in the water area of the Black Sea are given. Different parameters of the recorded infrasonic signal - the direction and phase velocity of arriving infrasonic waves, spectral composition, and coherence - have been studied. Wind and wave conditions in the water area of the Black Sea were studied in...
On the French Polynesian infrasound station I24FR, the wind noise reducing system is based on an 18 m diameter star array with 32 low impedance inlets. In the framework of the station upgrade, the question to use 96 air inlets instead of 32 air inlets is tackled. Global assessment on performances, investment and maintenance will be considered with respect to WNRS.
The vertical structure of wind field in the upper stratosphere and mesosphere obtained by infrasound probing method is studied. The method is based on the effect of infrasound scattering from highly anisotropic wind velocity and temperature inhomogeneities in the atmosphere. The vertical wavenumber spectra and coherences of the retrieved vertical profiles of wind velocity fluctuations are...
Recent advances in numerical wave propagation modeling and station coverage has permitted robust inversion of infrasound data from volcanic explosions. Complex topography and crater morphology has been shown to substantially affect the infrasound waveform, suggesting homogeneous acoustic propagation assumptions are invalid. Volume flux estimates from the infrasound waveform inversion provide...
Korea Institute of Geoscience and Mineral Resources (KIGAM) has installed an infrasound sensors since May 2014 on the existing eight seismic stations of PS31 called KSRS which is composed of 26 seismic sensors with a 40-km aperture. The installed acoustic sensors are collocated with the seismic stations of KSRS. This changes part of KSRS into a seismo-infrasound array, the Korea...
Long duration measurements have been obtained at the University of Mississippi Field Station. These tests compared bare sensors to sensors treated with porous hoses, and sensors under circular domes of different diameters (1.15, 1.50, 2.40 and 6.00 m). The domes used a variety of external claddings, including 2.5cm thick foam and perforated aluminum meshing (typically the holes had a diameter...
The loss of coherence in the infrasonic arrays have been introduced by Mack & Flinn (1971) and have since been heavily studied (Blandford, 2002) , (Nouvellet, 2013), (Green, 2013). The loss of coherence (LOC) is derived from uncertainties on the source wavefront. This leads to a loss of coherence that is function of both the distance between the sensors, and the frequency. In this study, we...
A large number of IMS infrasound stations are installed at remote locations without reliable grid coverage and stable power supply. One of the commonnly used sources of electricity is photovoltaic system and battery bank. Although the use of solar energy is not a new concept, there are no off-the-shelf packages ready to be deployed at all the stations. In addition, complicated access and...
A kind of least-squared-error localization algorithm applied on wide spread infrasound network is proposed in this article. Model of cross correlation between distant sensors and atmosphere infrasound propagation are analyzed. The localization error caused by quantity and distribution structure of network and ray tracing of local infrasound in real atmosphere are also calculated. Infrasound...
The infrasound component of the International Monitoring System (IMS) consists of sixty stations, including forty-seven certified stations transmitting continuous data to the International Data Centre (IDC) in Vienna, Austria. Each infrasound station is composed of an array of infrasound sensors capable of measuring micropressure changes produced at ground level by infrasonic waves. The...
The Pilot Interlaboratory Comparison Study (the "Pilot Study") was initiated based on recommendations of the Infrasound Expert Group Meetings 2013 and 2014. The scope of the Pilot Study includes the review of the state-of-the-art methods used in the characterization, testing and evaluation of infrasound sensors with the long-term objective of performing Interlaboratory Comparisons. The Pilot...
In the report of its 43rd session published in September 2014, Working Group B tasked the PTS to integrate a passive calibration technique based on side-by-side comparison into the IMS infrasound network. IS26 (Freyung, Germany) was selected as a pilot station, and the technique was installed there in May 2015. In this work, we present the integration of the calibration technique at IS26. We...
Kazakh NDC provides infrasound signal detection and event localization since 2013. Data come from a network consisting of two Kazakhstani infrasound arrays IS31 and Kurchatov and also Russian station IS46. Construction of another infrasound array at Kazakhstan is at the final stage. It is at the East of Kazakhstan. The station collocates with seismic array at Makanchy, PS23. For the moment...
IMS Infrasound stations detect mostly signals from Mountain Associated Waves at frequency range [0.015 - 0.1Hz]. MAWs are generated as hydrodynamic oscillation in the turbulent wind-stream in the lee of high mountain ranges (Meecham, 1971). Amplitude attenuation of MAWs from Drakensberg Mountain range is studied. Observed attenuation at two IMS infrasound stations IS35 and IS47 was compared...
The Comprehensive Nuclear-Test-Ban Treaty was ratified by the Russian Federation on 30 June 2000. According to the Treaty there are four IMS infrasound stations in Russia, which are located in Dubna (IS43), Petropavlovsk-Kamchatskiy (IS44), Ussuriysk (IS45) and Zalesovo (IS46). During operation Russian IMS infrasound stations there are different problems, such as flooding of station's...
On October 28, 2014 the launch of an Antares rocket from the Wallops Island Air Force Base in northern Virginia on the US eastern seaboard failed. To prevent the uncontrolled damage that could result from an uncontrolled launch the rocket was detonated. The detonation occurred at about 18:22:45 local time, producing a large explosion. Propagation conditions at the time were ideal: there was a...
The 2012 Infrasound Expert Group Meeting Report includes number of recommendations to the improvement of meteorological observations at CTBTO / International Monitoring System (IMS) infrasound stations, including investigation of the possibility of IMS observations to get closer to to World Meteorological Organization (WMO) standards, use of absolute pressure sensors at infrasound stations...
In the context of the ARISE research infrastructure project, an infrasound data portal has been developed. The portal will provide access to raw infrasound data from European stations as well as advanced data products that are useful for civil applications and the study of atmospheric structure using infrasound data. In this presentation, the current features and future developments of the...
The proposed method is based on the decomposition of infrasonic signals from pulsed sources. The recorded infrasonic signal is decomposed on a sequence of the acoustic pulses having the forms of U and N waves. Each U and N wave corresponds to the reflection of sound from the atmospheric inhomogeneities at different altitudes in the atmosphere. By determining the time intervals between such...
The spatial correlation of infrasound signals influences both infrasound array design and signal detectors. Previous atmospheric acoustic studies have identified anisotropic coherence loss across infrasound arrays, with greater loss for sensor-separations perpendicular to the direction of propagation than parallel. A recent study confirmed this anisotropy for International Monitoring System...
We investigate the impact of rough surface topography on atmospheric infrasound propagation by means of full 3D numerical simulations. The geometry of the reflecting surface and/or structures near the acoustic source strongly influences the development of acoustic waves, thereby affecting the sound radiation patterns in the far field. The linearized Euler equations, describing acoustic...
Due to the sparse nature of the 60 station International Monitoring System (IMS) infrasound array network, correctly associating multiple signals with an acoustic source is challenging. The process is made more difficult by detection schemes that struggle to distinguish between small local sources and the large distant sources of interest to the Comprehensive Nuclear-Test-Ban Treaty...
In the framework of incoming IS stations recapitalization, it is mandatory to improve our knowledge on wind noise reducing system. For that, some simulations and on field experiments were carried out. The results are discussed according to different multi inlets configurations. These elements will provide some useful information in the choice of the future new WNRS.
