Monitoring the Earth’s Atmosphere with the Global IMS Infrasound Network

Brachet, Nicolas; Brown, David; Bras, Ronan Le; Cansi, Yves; Mialle, Pierrick; Coyne, John

doi:10.1007/978-1-4020-9508-5_3

Cited by 99 publications

(87 citation statements)

References 17 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…From the telescopically determined number of nearEarth asteroids and their typical orbits we can compute the average interval between Earth impactors of a given energy. Energy for telescopic data was computed assuming a mean bulk density of 3,000 kg m 23 and average impact velocity of 20.3 km s…”

Section: Letter Researchmentioning

confidence: 99%

A 500-kiloton airburst over Chelyabinsk and an enhanced hazard from small impactors

Brown

Assink

Astiz

et al. 2013

Nature

383

308

View full text Add to dashboard Cite

Most large (over a kilometre in diameter) near-Earth asteroids are now known, but recognition that airbursts (or fireballs resulting from nuclear-weapon-sized detonations of meteoroids in the atmosphere) have the potential to do greater damage 1 than previously thought has shifted an increasing portion of the residual impact risk (the risk of impact from an unknown object) to smaller objects 2 . Above the threshold size of impactor at which the atmosphere absorbs sufficient energy to prevent a ground impact, most of the damage is thought to be caused by the airburst shock wave 3 , but owing to lack of observations this is uncertain 4,5 . Here we report an analysis of the damage from the airburst of an asteroid about 19 metres (17 to 20 metres) in diameter southeast of Chelyabinsk, Russia, on 15 February 2013, estimated to have an energy equivalent of approximately 500 (6100) kilotons of trinitrotoluene (TNT, where 1 kiloton of TNT 54.185310 12 joules). We show that a widely referenced technique 4-6 of estimating airburst damage does not reproduce the observations, and that the mathematical relations 7 based on the effects of nuclear weapons-almost always used with this technique-overestimate blast damage. This suggests that earlier damage estimates 5,6 near the threshold impactor size are too high. We performed a global survey of airbursts of a kiloton or more (including Chelyabinsk), and find that the number of impactors with diameters of tens of metres may be an order of magnitude higher than estimates based on other techniques 8,9 . This suggests a non-equilibrium (if the population were in a long-term collisional steady state the size-frequency distribution would either follow a single power law or there must be a size-dependent bias in other surveys) in the near-Earth asteroid population for objects 10 to 50 metres in diameter, and shifts more of the residual impact risk to these sizes. for the Chelyabinsk airburst, based on indirect illumination measured from video records. The brightness is an average derived from indirect scattered sky brightness from six videos proximal to the airburst, corrected for the sensor gamma setting, autogain, range and airmass extinction, following the procedure used for other airburst light curves generated from video 24,25 . The light curve has been normalized using the US government sensor data peak brightness value of 2.7 3 10 13 W sr 21, corresponding to an absolute astronomical magnitude of 228 in the silicon bandpass. The individual video light curves deviate by less than one magnitude between times 22 and 11.5 with larger deviations outside this interval. Time zero corresponds to 03:20:32.2 UTC on 15 February 2013. b, The energy deposition per unit height for the Chelyabinsk airburst, based on video data. The conversion to absolute energy deposition per unit path length assumes a blackbody emission of 6,000 K and bolometric efficiency of 17%, the same as the assumptions used to convert earlier US government sensor information to energy 26 . The heights are computed us...

show abstract

Section: Letter Researchmentioning

confidence: 99%

A 500-kiloton airburst over Chelyabinsk and an enhanced hazard from small impactors

Brown

Assink

Astiz

et al. 2013

Nature

383

308

View full text Add to dashboard Cite

show abstract

“…A coherent arrival in a particular time window and frequency band, detected when the consistency parameter (mean quadratic residual of the closure relations of the set of delays) is below a given threshold, is registered as a "pixel. " Nearby pixels that have similar wavefront properties are grouped together into families, based on the evaluation of a Euclidean distance equation that is configured with tuning parameters (see Table 3) [Brachet et al, 2010].…”

Section: Infrasound Measurements and Data Processing Techniquesmentioning

confidence: 99%

Evaluation of wind and temperature profiles from ECMWF analysis on two hemispheres using volcanic infrasound

et al. 2014

View full text Add to dashboard Cite

In this paper, we evaluate vertical wind and temperature profiles that are produced by the European Centre for Medium‐Range Weather Forecasts (ECMWF) atmospheric analysis. The evaluation is carried out on both hemispheres: we make use of stratospheric infrasound arrivals from Mount Etna (37°N) and Mount Yasur (22°S). The near‐continuous, high activity of both volcanoes permits the study of stratospheric propagation along well‐defined paths with a time resolution ranging from hours to multiple years. Infrasound observables are compared to theoretical estimates obtained from acoustic propagation modeling using the ECMWF analysis. While a first‐order agreement is found for both hemispheres, we report on significant discrepancies around some of the equinox periods and other intervals during which the atmosphere is in a state of transition and dynamical oscillations of the atmosphere dominate over the general circulation. We present an inversion study in which we make use of measured trace velocity estimates to estimate first‐order effective sound speed model updates in a Bayesian framework. Deviations from the a priori models around the stratopause up to 10% (≈ 30 m s−1) are estimated. Such updates are in line with the results from comparisons between ECMWF analysis and observations from lidar and microwave Doppler spectroradiometer facilities that were colocated during the course of the 2012–2013 Atmospheric dynamics Research and InfraStructure in Europe (ARISE) measurement campaign.

show abstract

“…They are grouped in mini-array stations including at least four sensors at distances of 1-3 km able to detect and characterize low coherent infrasound signals within the background noise. All technical aspects of infrasound monitoring related to sensors, stations and data processing have been redeveloped for CTBT verification Brachet et al 2010). In the last decade, detection bulletins determined from near-real-time analysis have been produced and correlated with observations of natural or man-made atmospheric sources, such as exploding meteoroids, volcanic eruptions, severe weather, hurricanes, earthquakes and ocean swelling .…”

Section: Arise Networkmentioning

confidence: 99%

Toward an Improved Representation of Middle Atmospheric Dynamics Thanks to the ARISE Project

et al. 2017

View full text Add to dashboard Cite

This paper reviews recent progress toward understanding the dynamics of the middle atmosphere in the framework of the Atmospheric Dynamics Research InfraStructure in Europe (ARISE) initiative. The middle atmosphere, integrating the stratosphere and mesosphere, is a crucial region which influences tropospheric weather and climate. Enhancing the understanding of middle atmosphere dynamics requires improved measurement of the propagation and breaking of planetary and gravity waves originating in the lowest levels of the atmosphere. Inter-comparison studies have shown large discrepancies between observations and models, especially during unresolved disturbances such as sudden stratospheric warmings for which model accuracy is poorer due to a lack of observational constraints. Correctly predicting the variability of the middle atmosphere can lead to improvements in tropospheric weather forecasts on timescales of weeks to season. The ARISE project integrates different station networks providing observations from ground to the lower thermosphere, including the infrasound system developed for the Comprehensive Nuclear-Test-Ban Treaty verification, the Lidar Network for the Detection of Atmospheric Composition Change, complementary meteor radars, wind radiometers, ionospheric sounders and satellites. This paper presents several examples which show how multi-instrument observations can provide a better description of the vertical dynamics structure of the middle atmosphere, especially during large disturbances such as gravity waves activity and stratospheric warming events. The paper then demonstrates the interest of ARISE data in data assimilation for weather forecasting and re-analyzes the determination of dynamics evolution with climate change and the monitoring of atmospheric extreme events which have an atmospheric signature, such as thunderstorms or volcanic eruptions.

show abstract

Monitoring the Earth’s Atmosphere with the Global IMS Infrasound Network

Cited by 99 publications

References 17 publications

A 500-kiloton airburst over Chelyabinsk and an enhanced hazard from small impactors

A 500-kiloton airburst over Chelyabinsk and an enhanced hazard from small impactors

Evaluation of wind and temperature profiles from ECMWF analysis on two hemispheres using volcanic infrasound

Toward an Improved Representation of Middle Atmospheric Dynamics Thanks to the ARISE Project

Contact Info

Product

Resources

About