The Deelen Infrasound Array for Recording Sonic Booms and Events of CTBT Interest (original) (raw)
Related papers
Advances in Space Research
In the frame of the European H2020 project ARISE, a short wave infrared (SWIR) InGaAs camera has been operated at the Haute-Provence Observatory, during a night that corresponds to the peak of Geminid meteor shower to investigate infrasound associated with meteor arrivals. This camera allows continuous observations during clear-sky nighttime of the OH airglow layer centered at 87 km. These observations were collocated with Rayleigh lidar measurements providing vertical temperature profiles from the lower stratosphere to the altitude of the OH layer around the mesopause. Spectral analysis of OH images did not allow to detect infrasound associated with meteor trails, however it reveals a peak corresponding to infrasound signals in the frequency band of those produced by ocean swell. Infrasound wave activity observed from ground-based microbarometers as well as the OH camera, appear to be modified with the presence of a temperature inversion described by Rayleigh lidar. Indeed, there is a difference in energy related to infrasonic activity between the first part of the night during the temperature inversion and after the inversion.
Studies of Microbaroms Using Multiple Infrasound Arrays
2001
Abstract: Microbaroms, known to be produced by marine storms, are a prevalent infrasound signal due to the presence of strong storms over the oceans. Often the microbarom wave trains last for tens of hours allowing us to track the storm. When we perform a least-squares fit to plane-wave arrivals on the data we find the apparent source azimuth points to the center of the storm low-pressure center.
A particle velocity sensor to measure the sound from a structure in the presence of background noise
2005
The performance (or quality) of a product is often checked by measuring the radiated sound (noise) from the vibrating structure. Often this test has to be done in an environment with background noise, which makes the measurement difficult. When using a (pressure) microphone the background noise can be such that it dominates the radiated sound from the vibrating structure. However, when using a particle velocity sensor, the Microflown [1,2], near the vibrating structure, the background noise has almost no influence (it is almost cancelled) and the sound from the structure is measured with a good S/N ratio. The experimental results are explained in terms of the different boundary conditions at the surface of the vibrating structure for the pressure and the particle velocity.
Infrasound monitoring of atmospheric events
2003
ABSTRACT In the second half of the twentieth century there was an intense international effort to establish a global seismic observing system that could reveal the Earth's inner structure and reduce hazards posed by earthquakes.
Infrasound produced by debris flow: propagation and frequency content evolution
Natural Hazards, 2011
Rapid mass movements such as avalanches, debris flows, and rock fall are periodic or episodic phenomena that occur in alpine regions. Recent studies have shown that debris flows generate characteristic signals in the low-frequency infrasonic spectrum (4-15 Hz). Infrasound can travel thousands of kilometers and can still be detectable. This characteristic provides a basis for the development of wide area automated monitoring systems that can operate in locations unaffected by the activity of the process. This study focuses on the infrasound vibrations produced by a debris flow at the Lattenbach torrent, Tyrol (Austria), and by two events at the Illgraben torrent, Canton of Valais (Switzerland). The Lattenbach torrent is a very active torrent, which is located in the west of Tyrol in a geologic fault zone between the Silvrettakristallin and the Northern Limestone Alps. It has a large supply of loose sediment. The Illgraben torrent, which is well known for its frequent sediment transport and debris flow activity, has been equipped with instruments for debris flow monitoring since the year 2000. This study shows that debris flow emits low-frequency infrasonic signals that can be monitored and correlated with seismic signals. During the passage of the debris flow, several surges were identified by ultrasonic gauges and detected in the time series and the running spectra of infrasonic data.
New options in microphones and instrumentation for making field infrasonic measurements
Journal of The Acoustical Society of America, 2010
There are many interesting man-made, animal and other naturally occurring infrasonic signals. Typical measurement microphones and instrumentation systems are usually AC coupled and roll-off at various frequencies below 20 Hz since they were primarily designed for audible sound. Making infrasonic measurements has often used a variety of sensors or microphones that aren't uniform or compliant with international standard IEC 61094 for dimensions of measurement microphones but offer capabilities for measuring to frequency ranges below 1 Hz. In addition they typically aren't compliant with ANSI or IEC standards for sound level meters. This is an overview of new IEPE/ICP condenser type measurement microphones and instrumentation capable of making measurements below 0.5 Hz and how they can be deployed in making precision acoustic field measurements compliant with acoustic standards at very low frequency ranges. This covers the microphones, accessories, and instrumentation required for precision field infrasonic measurements.
The detectability of infrasound in The Netherlands from the Italian volcano Mt. Etna
Journal of Atmospheric and Solar-Terrestrial Physics, 2005
Infrasound from the eruptions of Mt. Etna was detected in The Netherlands at the Deelen Infrasound Array (DIA) during the summer of 2001. Zonal cross winds lead to a deviation in the observed back azimuth. An average azimuthal deviation of 2:6 is explained by westward stratospheric winds along the infrasonic trajectories through the atmosphere. The signals have signal-to-noise power ratios lower than 0.6. The detectability of Mt. Etna's infrasound is tested on subarrays of the 13 elements of DIA. Doing so, sparse arrays used in the International Monitoring System (IMS) are mimicked. Both small aperture sub-arrays of 800 m and large aperture sub-arrays of 1400 m are applied. The results are evaluated on the basis of the number of detections made. The number of detections strongly increases with the number of elements. Small aperture sub-arrays perform significantly better than large aperture sub-arrays. With a factor of two reduction in the aperture, two instruments less can be used to obtain the same number of detections. Larger aperture arrays perform less well because of the loss of spatial coherence of the infrasound. The average accuracy of the detections slightly increased, when the number of elements is increased. The result of the use of more elements is that lower signal-to-noise power ratio events could be detected. The trade-off between more detections and the larger average deviation in back azimuth and apparent sound speed causes the slight increase accuracy. The results were comparable to the detections obtained at IMS array IS26 in Germany. It is concluded that successfully applying infrasound as monitoring technique strongly depends on the array configuration. The frequency versus spatial coherence of signals will play a decisive role in detecting low signal-to-noise ratio events.