Bottom interaction in long range acoustic propagation
DOEI Project Funded: 2004
Project Summary
What are the primary questions you are trying to address with this research?
We are trying to understand long range acoustic propagation in the ocean in the
frequency band from 1 to 100Hz.
What is the significance of this research for others working in this field of
inquiry and for the broader scientific community?
We have a number of anecdotal observations that long range propagation in this
band is not adequately explained by traditional SOFAR channel propagation. Our
goals are: 1) to understand the interplay between oceanographic mode coupling
(internal waves, etc), bathymetric mode coupling (abyssal hills, sea mounts,
mid-ocean ridges, etc), and bottom attenuation, and 2) to observe the vertical
structure of T-phases and the seabed response to controlled sources for validation
against forward models.
What is the significance of this research for society?
Underwater sound in this frequency band is used to study a broad range of processes
including marine mammal activity and marine seismology (earthquakes under the
ocean). In order to make progress in these disciplines we need to understand
the acoustic propagation process.
When and where will this investigation be conducted?
This project will make seafloor seismic observations in the
North Pacific from September 2004 to July 2005.
What are the key tools or instruments needed to conduct this research?
Ocean Bottom Seismometers
What are the greatest challenges - physical or intellectual - to
conducting this investigation?
Our seafloor observation systems push the limits of available low-power computer
technology. We also use advanced mathematics to quantitatively predict long
range acoustic propagation for comparison with observations.
Is this research part of a larger project or program?
Not yet. We are using this opportunity to provide material for a
proposal for a larger program.