Deep-Water Ambient Noise Profiling; Marine Sediment Acoustics; and Doppler Geo-Acoustic Spectroscopy
SCRIPPS INSTITUTION OF OCEANOGRAPHY LA JOLLA CA MARINE PHYSICAL LAB
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The scientific objective of the deep-water ambient noise research is to measure the second-order spatial statistics of the ambient noise in the deepest oceans as a function of depth, from the sea surface to the seabed. Regions of interest include the Challenger Deep in the Mariana Trench 11 km, the Tonga Trench 9 km, and the Puerto Rico Trench 8 km. Environmental and system data will also be depth-profiled, including temperature, salinity, pressure and sound speed, along with all system motions translational and rotational. Theoretical modeling of the spectral, spatial and temporal properties of the ambient noise will also be performed. The sediment acoustics research is aimed at developing a unified theory of wave propagation in marine sediments in the form of the dispersion relations for the compressional and shear waves. Besides the frequency dependencies of the wave speeds and attenuations, these expressions will also return the dependence of the wave parameters on the mechanical properties of the sediment, namely porosity, density, grain size and overburden pressure. The Doppler geo-acoustic spectroscopy technique, in which an aircraft is used as a sound source, is in support of the sediment acoustics research, providing a means of measuring the sound speed in the sediment at frequencies between 80 and 1000 Hz.
- Geology, Geochemistry and Mineralogy