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Tracing a meteoric trajectory with infrasound

Tracing a meteoric trajectory with infrasound. Läslo Evers and Hein Haak evers@knmi.nl http://www.knmi.nl/~evers Royal Netherlands Meteorological Institute (KNMI) Seismology Division. The presented work is under review with Geoph. Res. Lett. Dutch Infrasound Arrays. 2003 February 19

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Tracing a meteoric trajectory with infrasound

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  1. Tracing a meteoric trajectory with infrasound Läslo Evers and Hein Haak evers@knmi.nl http://www.knmi.nl/~evers Royal Netherlands Meteorological Institute (KNMI) Seismology Division The presented work is under review with Geoph. Res. Lett.

  2. Dutch Infrasound Arrays

  3. 2003 February 19 18h18m24.08s GMT Meteoric Infrasound in DBN

  4. Detections at DBN

  5. 2003 February 19 18h17m59.31s GMT Meteoric Infrasound in DIA

  6. Detections at DIA

  7. Resolution I: Fisher ratio response

  8. Best beam 2nd arrival: 359.0 deg and 335.6 m/s Best beam 1st arrival: 1.0 deg and 359.9 m/s Resolution II: best beams at DIA

  9. 2003.02.19 18h17m57.28s 1.0o 359.9 m/s 32.3o 341.5 m/s 35.8o 373.5 m/s 359.0o 335.6 m/s Summary of the observations

  10. Localization through cross bearing

  11. What is known? • Arrival times of the different phases at DBN and DIA • Bearing and range from cross bearing What might be derived and why? • 4D source characteristics: location and time. Is the source moving (bolide) or static (nuclear test)? What can be used for validation? How? • Reported time of occurrence of 18h13m05s • Observed approximate direction from S to N • Least squares optimization of observed and modeled differential traveltimes for different heights

  12. Atmospheric models

  13. Raytracing for the 1st arrival DIA

  14. Observed Δt: 2.94±0.01 s Minimum at 0.03 s: 32, 56 km Observed Δt: 3.37±0.15 s found at 0.22 s: 27, 57 km Differential traveltime modeling

  15. Trajectory reconstruction

  16. Conclusions and discussion • The source is identified as moving, this bolide could be located in 4D by two nearby arrays. • Reported time of occurrence and path confirmed. • Only convergent solutions found for ECMWF models. • snr of 17 in DBN and 2 in DIA: spatial coherence lost in larger aperture array, resp. 60 and 1500 m. • Average of DBN and DIA origin time correct, but an absolute difference of ~8 sec caused by uncertainties in model and bearings.

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