2019_programme: USING SHIPS OF OPPORTUNITY TO ESTIMATE SOUND SPEED PERTURBATIONS BY THE TOMOGRAPHIC METHOD
- Session: 10. Design of new experimental facilities to address future problems in underwater acoustics
Organiser(s): Sessarego Jean-Pierre, Fattaccioli Dominique, Real Gaultier
- Lecture: USING SHIPS OF OPPORTUNITY TO ESTIMATE SOUND SPEED PERTURBATIONS BY THE TOMOGRAPHIC METHOD [invited]
Paper ID: 967
Author(s): Gemba Kay L., Paralta Heriberto Vazquez, Sarkar Jit, Cornuelle Bruce, Hodgkiss William, Kuperman W.A.
Presenter: Gemba Kay L.
Presentation type: oral
Abstract: Through-the-sensor environmental characterization approaches are useful in dynamic ocean environments. For example, parameters or processes of interest include the sound speed (temperature) field with mesoscale resolution, currents, or eddy kinematics and dynamics. When fused with near surface observations obtained by other sensing modalities such as high-frequency radar or satellite-based sensors, the inferred regional oceanographic information becomes an important component for a variety of applications and also can be used as one of several priors to predict global ocean state. \n\nIn this data-assimilation framework, we consider the added benefit and information content of noise sources such as ships of opportunity. Ships provide the equivalent of many high amplitude source positions. We previously demonstrated that relative channel impulses are sufficiently accurate (on the order of 10 microseconds) to distinguish between a “daily” sound speed and the extreme (min/max) sound speeds, all observed over the duration of an experiment. Underwater acoustic observatories potentially can be configured to acquire these data used to infer real-time water-column sound speed perturbations. \n\nConsistent with an incremental approach, we consider how moving sources can be used for ocean acoustic tomography. The question to be discussed is the following: given the statistical variance in travel time associated with model shortcomings and the precision with which the timing of the shipborne (active) source and moored receivers can be measured from the observations, what fraction of the ocean sound speed variance in a region (i.e., 3 dimensional) can be reconstructed by the tomographic method? Results are demonstrated with simulations and the Santa Barbara Channel experiment 2016.
- Corresponding author: Dr Gemba Kay
Affiliation: Scripps Institution of Oceanography
Country: United States