Systems Check

1. Systems Check Hydronynamics by Don Korycansky, http://www.ucolick.org/~kory/impacts

2. INFRASONIC SOURCE LOCATION USING THE TAU-P METHOD Milton Garces and Claus Hetzer Infrasound Laboratory, University of Hawaii, Manoa Kent Lindquist Lindquist Consulting Douglas Drob Naval Research Laboratory 2002 Infrasound Technology Workshop, Netherlands

3. Introduction • Location accuracy determined by wind conditions and proper arrival identification • Apply tau-p model to telesonic events detected in the Pacific • April 23, 2001 and August 25, 2000 (Acapulco) Bolides • Bolides are not ideal sources, but options are limited

4. Wind Structure Wind structure for the great circle path from April 23 source to IS59, Hawaii Wind structure for the great circle path from April 23 source to IS53, Alaska

5. Phase ID Description Typical celerity of first arrival, m/s iw Guided wave propagating between the tropopause and the ground. 330-340 is Guided wave propagating between the stratopause and the ground. 310-330 isd Guided wave propagating in elevated waveguide between stratopause and the troposphere, and diffracted or scattered to the ground. May have higher frequency. 310-330 it Guided wave propagating between the lower thermosphere and the ground. 280-300 itd Guided wave propagating in elevated waveguide between the lower thermosphere and the troposphere, and diffracted or scattered to the ground. 280-300 It, Is, Iw Direct arrival from the source to the receiver. May have high apparent phase velocity N/A Phases Table 1. Preliminary phase identification nomenclature for long-range infrasonic propagation

6. Travel Times, Azimuth Deviation, Range, and t Surfaces (2000) • The next panel shows the travel time, range, azimuth deviation, and t as a function of arrival azimuth and incidence angle in the Poker Flat, AK. The t function is defined as t = T - pX, where T is the travel time, p is the conserved ray parameter, and X is the range (see for example Garcés et al., 1998). This figure was also generated by is_sphere. • The observed angle of arrival determines the three components of the infrasound wave-number vector - kew, kns, and kz. • These figures plot the first skip of a surface source. Multiple skips would correspond to integer multiples of these values. • Note that the t surface shows the monotonic, piecewise-continuous property of the t function, which makes it ideal for interpolation and operational implementation.

7. Characteristic Surfaces for Propagation at Poker Flat

8. Tau9.1

9. Turning Slowness

10. 2D Model 1D Model Output This is where tau comes into play

11. Great Balls of Fire: Match Origin Time Satellite (LO) and infrasonic (LA_DL2) location for the Acapulco bolide. The observed arrival azimuths at infrasound arrays IS08. IS25, IS53, DLIAR, and IS59 are shown as red lines. Satellite (LO) and infrasonic (LA_S1) location for the April 23, 2001 bolide. The observed arrival azimuths at infrasound arrays IS53, IS57, and IS59 are shown as red lines.

12. Source it Lat (N) itd Lon (E) isd Origin Time (Epoch) Lat error (deg) Lon error (deg) Time error (s) IS53 0.268 0.284 0.292 LO1 27.9 -133.89 988006355 0 0 0 IS57 0.278 0.292 0.328 LA_S1 28.07 -135.09 988006347 0.17 -1.2 -8 IS59 0.284 0.3 0.311 LA_S2 27.79 -133.42 988006145 -0.11 0.47 -210 April 23 Bolide Used 1D Models Table 2.2. Predicted first arrival celerity (km/s) for select phases: April 23, 2001 (1D) Table 2.3. Source location and errors relative to satellite location (LO1): April 23, 2001

13. April 23: IS59

14. April 23: IS59

15. April 23: IS57

16. April 23: IS57

17. April 23: IS53

18. April 23: IS53

19. Source it Lat (N) itd Lon (E) isd Origin Time (Epoch) Lat error (deg) Lon error (deg) Time error (s) IS53 0.268 0.284 0.292 LO1 27.9 -133.89 988006355 0 0 0 IS57 0.278 0.292 0.328 LA_S1 28.07 -135.09 988006347 0.17 -1.2 -8 IS59 0.284 0.3 0.311 LA_S2 27.79 -133.42 988006145 -0.11 0.47 -210 April 23 Bolide Used 1D Models Table 2.2. Predicted first arrival celerity (km/s) for select phases: April 23, 2001 (1D) Table 2.3. Source location and errors relative to satellite location (LO1): April 23, 2001

20. Source Lat (N) Lon (E) Origin Time (Epoch) Lat error (deg) Lon error (deg) Time error (s) it itd isd LO1 14.45 -106.13 967165945 0 0 0 IS08 0.289 0.298 LA_DL1 13.68 -108.21 967166247 -0.77 -2.08 302 IS25 0.263 0.285 0.29 IS53 0.292 0.303 0.31 LA_DL2 13.37 -107.74 967165950 -1.08 -1.61 5 IS59 0.281 0.297 0.308 DLIAR 0.278 0.309 Acapulco Bolide Table 3.2. Predicted first arrival celerity (km/s) for select phases: August 25, 2000 Table 3.3. Source location and errors relative to satellite location (LO1): August 25, 2000

21. Acapulco: IS53

22. Acapulco: IS59

23. Acapulco: DLIAR

24. Acapulco: SA From A. Le Pichon, CEA/DASE: Infrasonic detections of the Acapulco bolide in South America IS25 - French Guiana q = 325° IS08 - Bolivia

25. Source Lat (N) Lon (E) Origin Time (Epoch) Lat error (deg) Lon error (deg) Time error (s) it itd isd LO1 14.45 -106.13 967165945 0 0 0 IS08 0.289 0.298 LA_DL1 13.68 -108.21 967166247 -0.77 -2.08 302 IS25 0.263 0.285 0.29 IS53 0.292 0.303 0.31 LA_DL2 13.37 -107.74 967165950 -1.08 -1.61 5 IS59 0.281 0.297 0.308 DLIAR 0.278 0.309 Acapulco Bolide Table 3.2. Predicted first arrival celerity (km/s) for select phases: August 25, 2000 Table 3.3. Source location and errors relative to satellite location (LO1): August 25, 2000

26. Concluding Remarks • Stratospheric and thermospheric phases propagating in elevated ducts are invoked to explain observed celerities • Present limitations in location accuracy may be due to granularity of climatological models and our understanding of infrasonic scattering and diffraction in the atmosphere • April 23 bolide origin time best matched by results of 1D profiles • Acapulco bolide origin time best matched by results of 2D profiles Benchmark events provide new tests!