3.6
Models for the Analysis and Prediction of Acoustic Phenomena in the Coastal Ocean
Paul C. Etter, Northrop Grumman Corporation, Annapolis, MD
This paper identifies and describes models that are appropriate for the analysis and prediction of acoustic phenomena in the coastal ocean. When coupled with coastal atmosphere-ocean models, these ocean-acoustic models function as sophisticated prognostic and diagnostic tools for naval operations, offshore industries and oceanographic research.
Broadly defined, ocean acoustics entails the development and employment of acoustical methods to image underwater features, to communicate information via the oceanic waveguide, or to measure oceanic properties. Useful information about the ocean can be derived from both forward and inverse applications of underwater sound. Traditional forward-sensing techniques are routinely used to obtain measurements of bottom topography (echo sounders and side-scan sonars) and water currents (acoustic Doppler current profilers). In addition, the acoustic phenomena of propagation and noise have been used in inverse fashions to infer information about the thermal structure of the water column and the state of the sea surface.
In advance of naval operations, it is necessary to collect meteorological and oceanographic data from remote or hostile coastal environments to forecast acoustic sensor performance. Coupled atmosphere-ocean-acoustic models could reduce the need for hazardous in-situ data collection by numerically computing initial states for the embedded acoustic models.
Offshore industries have become more reliant on the use of autonomous undersea vehicles (AUVs) and remotely operated vehicles (ROVs) to reduce safety risks and to maximize operating efficiency. These systems must perform in noisy, shallow-water environments using an array of acoustic sensors for navigation, docking, tracking and communication. Coupled models could provide operational ocean-acoustic forecasts to the offshore industries.
As already noted, oceanographic research can benefit from both forward and inverse applications of underwater sound. Coupled models would enhance the planning and analysis of ocean-acoustic field experiments. Environmental research issues associated with the employment of acoustical methods in the coastal ocean include protection of marine mammals from noise in addition to abatement of noise on platforms and vessels.
A review of requirements for coupling ocean-acoustic and atmosphere-ocean models in coastal environments suggests a broad architectural plan for their common integration. Issues critical to the further integration of atmosphere-ocean-acoustic modeling technologies have also been identified including high-level architectures (HLA), data standards and VV&A (verification, validation and accreditation) standards. Collectively, these initiatives seek to promote modeling reuse and interoperability among diverse user communities.
Session 3, Ocean Modeling
Thursday, 8 November 2001, 3:15 PM-4:45 PM
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