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Global Infrasound Monitoring – Research and Applications

Global Infrasound Monitoring – Research and Applications. Henry E. Bass, Carrick Talmadge , and Kenneth Gilbert , National Center For Physical Acoustics, University of Mississippi

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Global Infrasound Monitoring – Research and Applications

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  1. Global Infrasound Monitoring – Research and Applications Henry E. Bass, Carrick Talmadge, and Kenneth Gilbert, National Center For Physical Acoustics, University of Mississippi Michael Hedlin, Gerald D’Spain, and Jon Berger, Scripps Institution of Oceanography, University of California San Diego Milton Garces and Claus Hetzer, ISLA, University of Hawaii John V. Olson, Charles Wilson, Curt Szuberla and Daniel Osborne, University of Alaska at Fairbanks Paul Golden and Gene Herrin, Southern Methodist University Richard Kromer and Pres Herrington, Sandia National Laboratory Rod Whitaker and Doug Revelle, Los Alamos National Laboratory Keith McLaughlin, Joydeep Bhattacharyya, Bob Woodward and Bob North, SMDC Monitoring Research, Arlington, VA David Norris and Rob Gibson, BBN Technologies, Arlington, VA

  2. Research Issues • Use of Infrasound Data to Further other Research Hazard Warning Meteorology Sprite Physics Bolide Distributions • Research Needed to Optimize Infrasound Station Performance • Wind Noise Reduction • Signal Processing Techniques and Processes • Research Needed to Optimize Use of Data • Source Characterization • Meteorological Effects

  3. GE: Earthquakes, Tsunamis, Avalanches LePichon, 2001: Arequipa Earthquake June 23, 2001 • Civil Disaster Management Mb = 4.3 at IS59

  4. GE: Volcanoes • Eruption and ash monitoring • Eruption forecasting • Atmospheric tomography IS59: Kilauea, Mauna Loa, and Hualalai, Hawaii Hekla, Iceland (Lizska, 2001) IS55: Erebus, Antarctica LePichon, 2001: Etna, Italy

  5. GE: Severe Weather • Microbaroms may allow storm tracking with infrasound Microbaroms and surf (800x)

  6. Meteorological Effects • Speed of Sound Varies With Altitude, Location and Time • Current Meteorological Models and Limitations • Propagation Models/Verification • Tomography

  7. The Speed of Sound is Determined by Wind Speed and Temperature

  8. GE: Electromagnetic Activity • Sprites, Aurora source at 90 km height Liszka, 2001: Sprites in Sweden May 26/27, 1995

  9. GE: Bolides • Bolide impact distribution will be modified by new infrasonic recordings – get stats! 2001 Leonid recorded at IS59 April 23, 2001 ~10kt

  10. GE: Turbulence and Atmospheric Waves • Clear air turbulence monitoring • Lower, middle and upper atmosphere dynamics

  11. GE: Littoral Processes Kualanui 100X

  12. Microbarams • Progress towards predicting amplitude and frequency dependence – not just existence.

  13. Coastal surf activity

  14. Geophysical Events: IS10 Brown, 2000, in McCormack, 2001 N IS10 Winnipeg, Canada December 16, 1999 to September 1, 2000 Approximately 4200 detections microbaroms, Hudson Bay ? Local blasting, Too small to register on local seismic ? W E Local blasting Thunder Bay area, too small to register on local seismic mining activity, Minnesota, registers strongly on local seismic microbaroms, Pacific Ocean (?) S

  15. Geophysical Events • Ground Truth Event Database is growing: CMR and IDC • Some sources are poorly characterized Subset of CMR GT Database

  16. Source Characterization • Explosions • Weather • Lightning • Volcanoes • Bolides • Earthquakes, Tsunamis, etc.

  17. Research Needed to Optimize Infrasound Station Performance • Wind Noise • Infrasonic Wave Propagation • Sensors and calibrators

  18. Wind Noise

  19. Wind-noise-reducing filters • 120-port design • Valves at each port and at main manifold • PVC construction • Custom manifolds, off-the-shelf fittings • Fenced area

  20. Alternatives to Spatial Filtering • OFIS – Still filters spatially but sums at the speed of light. • Microphone Arrays – Still filters spatially but sums at the speed of light. • Active wind noise correction.

  21. SI: Infrasonic Wave Propagation • Some progress in integration of required environmental information for modeling – further work required to resolve outstanding issues such as: • observed errors in azimuth • phase identification • scattering and diffraction • Final goal of an operational full modeling capability (waveforms, travel times, phase velocities, amplitudes) • Continue to collect ground truth data and associated environmental information

  22. SI: Sensors and calibrators • A number of new sensor technologies are under development • Global network should continue to take advantage of innovations in infrasound technology • Need for field calibrators and calibration standards • Development of new sensor types should consider calibration requirements

  23. Concluding Remarks • Keep in mind that we do not understand most signals received – what are we missing? • We might be keen on improving our stations but the true value is in the information provided about physics of interest – not the station per se. • Hazard Warning is a Hot Topic but Hot Topics change – good physics remains good physics.

  24. The End

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