Sound Propagation in the Sea--Ray Tracing. Curvature Corrections for the Earth (Sea Level) Shaped as an Ellipsoid of Revolution.

摘要

The three-dimensional tracing of a sound ray in the sea may be referred to the surface coordinate system of latitude and longitude and to the depth below the sea surface. This coordinate system involves ccurvature terms. The earth shaped as an ellipsoid of revolution may be referred to two definitions of latitude: the geocentric latitude phi and the astronomical latitude Phi. These are illustrated in Fig. 2. There is a one-to-one relationship between these definitions and the transformation is simple as will be shown. The geocentric latitude phi was chosen as principal latitude coordinate. Let the direction of propagation of a sound ray at an arbitrary point in its progress -- latitude phi, longitude Theta and depth z -- be defined by the unit vector T. It makes the angle gamma with the horizontal as shown in Fig. 1. The horizontal component of the unit vector T defines the direction of the unit vector l c bold.