Reliable Acoustic Path (RAP) Tomography at the ALOHA Cabled Observatory.
Date
2017-12
Authors
Contributor
Advisor
Department
Instructor
Depositor
Speaker
Researcher
Consultant
Interviewer
Narrator
Transcriber
Annotator
Journal Title
Journal ISSN
Volume Title
Publisher
Volume
Number/Issue
Starting Page
Ending Page
Alternative Title
Abstract
Using a mobile ship platform (R/V Kilo Moana) with an acoustic source transmitting to a fixed
bottom hydrophone at the ALOHA Cabled Observatory (ACO), we are investigating the
feasibility of Reliable Acoustic Path (RAP) Tomography. This will allow the spatial mapping of
a path integrated sound speed (temperature) over a 60 km diameter “teacup” volume of the
ocean. This can be considered an extension of an inverted echosounder (from a vertical to near
horizontal path) combined with the precise positioning and timing of seafloor geodesy, where
their noise (sound speed variation) is our signal. As a first step in this pilot project, transmissions
were sent using an array of transducers at 3.5 kHz. Receptions at the hydrophone were recorded
as the vessel approached and departed from ACO. Actual travel times were compared with
estimated travel times that were calculated using CTD measurements. The next test employed
user-generated (LFM sweeps and M-sequences) signals and an improved experimental setup to
ensure a precise and accurate time of transmission. This experiment provided a more consistent
travel time that agreed better with estimated times, when compared to the earlier pilot test. For an
upcoming cruise with dedicated ship time, this setup will be used again. The vessel will traverse
circular and radial paths around the hydrophone to obtain multiple different acoustic paths in the
volume. Subsequent analysis of the data is expected to resolve the tidal cycle at ACO, increase
positioning accuracy of the bottom mounted hydrophone, and perform RAP Tomography.
Description
Keywords
Citation
Extent
Format
Geographic Location
Time Period
Related To
Related To (URI)
Table of Contents
Rights
All UHM dissertations and theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission from the copyright owner.
Rights Holder
Local Contexts
Collections
Email libraryada-l@lists.hawaii.edu if you need this content in ADA-compliant format.