Three-dimensional numerical modeling of bottom-diffracted surface-reflected arrivals in the North Pacific [poster]

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Date
2015-12-15Author
Stephen, Ralph A.
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Udovydchenkov, Ilya A.
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Bolmer, S. Thompson
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Komatitsch, Dimitri
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Tromp, Jeroen
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Casarotti, Emanuele
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Xie, Zhinan
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Worcester, Peter F.
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https://hdl.handle.net/1912/7740DOI
10.1575/1912/7740Abstract
Bottom-diffracted surface-reflected (BDSR) arrivals
were first identified in the 2004 Long-range Ocean
Acoustic Propagation Experiment (Stephen et al, 2013,
JASA, v.134, p.3307-3317). The BDSR mechanism provides
a means for acoustic signals and noise from distant
sources to appear with significant strength on the deep
seafloor. At depths deeper than the conjugate depth ambient
noise and PE- predicted arrivals are sufficiently quiet
that BDSR paths, scattered from small seamounts, can be
the largest amplitude arrivals observed. The Ocean
Bottom Seismometer Augmentation in the North Pacific
(OBSANP) Experiment in June-July 2013 was designed
to further define the characteristics of the BDSRs and to
understand the conditions under which BDSRs are excited
and propagate. The reciprocal of the BDSR mechanism
also plays a role in T-phase excitation. To further
understand the BDSR mechanism, the SPECFEM3D
code was extended to handle high-frequency, deep water
bottom scattering problems with actual bathymetry and a
typical sound speed profile in the water column. The
model size is 38km x 27km x 6.5km. The source is centered
at 10Hz with a 5Hz bandwidth. Work supported by
NSF and ONR.
Description
Poster presented AGU Fall Meeting, San Francisco, Californai USA, December 14-18, 2015