Acoustic Ray-Trace Equations for Seafloor Geodesy

Abstract

One goal of seafloor geodesy is to measure horizontal deformation of the seafloor with millimeter resolution. A common technique precisely times an acoustic signal propagating between two points to estimate distance and then repeats the measurement over time. The accuracy of the distance estimate depends upon the travel time resolution, sound speed uncertainty, and the degree to which the path computed from propagation equations replicates the actual path traveled by the signal. In this paper, we address the error from ray propagation equations by comparing three approximations to Snell's Law with ellipsoidal geometry.

Keywords:

• GPS-acoustics
• acoustic ranging
• ellipsoid
• deformation
• plate motion

Acknowledgements

This work was supported by BP America, Inc. and National Science Foundation grants OCE-0551765 and OCE-0850875 from the Marine Geology and Geophysics Program. We thank two anonymous reviewers for their thoughtful comments.