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Real Time System for Practical Acoustic Monitoring of Global Ocean Temperature. Volume 3

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Quarterly progress rept. no. 5, 1 Apr-30 Jun 1994

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Work continues on all GAMOT Tasks as described in ARPA Grant No MDA972-93-1-004. 1 Task A. Task A work remains on schedule and we have completed the following work We are writing a new eigenray finder for use in identifying the paths which sound take from sources to the surface suspended acoustic receivers A theoretical investigation has been conducted which has found that it is possible that ray theory can be extended to acoustic frequencies below 100 Hz A new parabolic approximation to the acoustic wave equation has been developed. Unlike all previous parabolic approximations, the new approximation predicts delays of acoustic pulses with little error The acoustic multipaths from the Kaneohe source have been identified at one SOSUS station using a ray tracing algorithm called ZRAY. This was a breakthrough since this is the furthest, 4000 km, that ray theory has been successfully used to understand acoustic propagation in the ocean 2 Task B. Task B tasks and deliverables are on schedule. We have completed writing of a manuscript detailing the travel time anomaly estimates using a reduced gravity model of the northeast Pacific. We have designed an acoustic tomography assimilation method for a similar model but with spatially variable density. The plan for monitoring the Pacific Ocean for long term change is contained in the Task B section 3 Task C. Fabrication of ten operational SSARs is continuing. Two units are being prepared for a test cruise at the AUTEC Range in August and two units are being prepared for testing in the Pacific in November. No significant delays or problems ahve been encountered and 4 Task D. The 70 Hz source proposal was submitted to ARPA on April 19, 1994. No action has yet been taken on the proposal

Subject Categories:

  • Physical and Dynamic Oceanography
  • Acoustic Detection and Detectors

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