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Sohn, RA, Vernon F, Hildebrand JA, Webb SC.  2000.  Field measurements of sonic boom penetration into the ocean. Journal of the Acoustical Society of America. 107:3073-3083.   10.1121/1.429336   AbstractWebsite

Six sonic booms, generated by F-4 aircraft under steady flight at a range of altitudes (610-6100 nl) and Mach numbers (1.07-1.26), were measured just above the air/sea interface, and at five depths in the water column. The measurements were made with a vertical hydrophone array suspended from a small spar buoy at the sea surface, and telemetered to a nearby research vessel. The sonic boom pressure amplitude decays exponentially with depth, and the signal fades into the ambient noise field by 30-50 m, depending on the strength of the boom at the sea surface. Low-frequency components of the boom waveform penetrate significantly deeper than high frequencies. Frequencies greater than 20 Hz are difficult to observe at depths greater than about 10 m. Underwater sonic boom pressure measurements exhibit excellent agreement with predictions from analytical theory, despite the assumption of a flat air/sea interface. Significant scattering of the sonic boom signal by the rough ocean surface is not detected. Real ocean conditions appear to exert a negligible effect on the penetration of sonic booms into the ocean unless steady vehicle speeds exceed Mach 3, when the boom incidence angle is sufficient to cause scattering on realistic open ocean surfaces. (C) 2000 Acoustical Society of America. [S0001-4966(00)03106-4].

Prieto, GA, Parker RL, Vernon FL.  2009.  A Fortran 90 library for multitaper spectrum analysis. Computers & Geosciences. 35:1701-1710.   10.1016/j.cageo.2008.06.007   AbstractWebsite

The spectral analysis of geological and geophysical data has been a fundamental tool in understanding Earth's processes. We present a Fortran 90 library for multitaper spectrum estimation, a state-of-the-art method that has been shown to outperform the standard methods. The library goes beyond power spectrum estimation and extracts for the user more information including confidence intervals, diagnostics for single frequency periodicities, and coherence and transfer functions for multivariate problems. In addition, the sine multitaper method can also be implemented. The library presented here provides the tools needed in multiple fields of the Earth sciences for the analysis of data as evident from various examples. (C) 2008 Elsevier Ltd. All rights reserved.

Park, J, Vernon FL, Lindberg CR.  1987.  Frequency-Dependent Polarization Analysis of High-Frequency Seismograms. Journal of Geophysical Research-Solid Earth and Planets. 92:12664-12674.   10.1029/JB092iB12p12664   Website