B - Ocean Acoustic Propagation Atlas

Summary

Climatological sound-speed profiles and predicted acoustic arrival patterns for selected locations worldwide (fig. B.1) are displayed in this appendix. The locations are from a regular grid spaced at 15° increments in latitude and 20° increments in longitude. [Worcester and Ma (in press) provide results for all grid locations exceeding 2000 m depth.] The atlas is organized by location, beginning at 75°N and proceeding southward. At each latitude, results are presented in order of longitude, proceeding westward from the prime meridian. The interpretation of the plots presented here is discussed at length in section 2.16. Each panel is described briefly, proceeding counterclockwise from the bottom left.

The sound-speed profiles (bottom left) were computed from annual-average climatological temperature and salinity data due to Levitus (1982), using the Del Grosso (1974) sound-speed equation. The Levitus climatology is a horizontally smoothed picture of the ocean, so the results do not properly represent the behavior to be expected in frontal regions.

Acoustic normal mode functions 1 and 7 computed for 70 Hz are displayed at bottom center. The amplitude normalization is arbitrary. The group velocity for each mode is given immediately below the mode function.

Time fronts in τ, z-space for a fixed range of 500 km (bottom right) show the arrival structure for a source on the sound-channel axis, when one exceeding 100 m depth exists, or for a source at 100 m depth.