Environmental Variability at Site Alfa during the Broadband-87 Exercise

The Broadband-87 acoustics exercise was an at-sea efforts designed to characterize broadband propagation. This experiment was conducted in two areas of the North Atlantic Ocean Site Alfa, 31 N, 76 W, was chosen for its acoustically bottom-limited conditions and characteristically stable oceanographi...

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Bibliographic Details
Main Authors: Bucca, Paul J, Meredith, Roger W
Other Authors: NAVAL OCEAN RESEARCH AND DEVELOPMENT ACTIVITY STENNIS SPACE CENTER MS
Format: Text
Language:English
Published: 1989
Subjects:
Physical and Dynamic Oceanography
Acoustic Detection and Detectors
*ACOUSTIC CHANNELS
*ACOUSTIC MEASUREMENT
*UNDERWATER SOUND SIGNALS
ACOUSTIC VELOCITY
BROADBAND
DISPLACEMENT
FLEET EXERCISES
GULF STREAM
OCEAN BOTTOM
OCEAN CURRENTS
OCEAN ENVIRONMENTS
OCEAN SURFACE
PROFILES
SOUND TRANSMISSION
STABILITY
SURFACE TEMPERATURE
TABLES(DATA)
TEMPERATURE
THERMOCLINES
VARIATIONS
WATER MASSES
PE63785N
North Atlantic
Online Access:http://www.dtic.mil/docs/citations/ADA214666
http://oai.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=ADA214666
Description
Summary:The Broadband-87 acoustics exercise was an at-sea efforts designed to characterize broadband propagation. This experiment was conducted in two areas of the North Atlantic Ocean Site Alfa, 31 N, 76 W, was chosen for its acoustically bottom-limited conditions and characteristically stable oceanographic environment. Site Delta, 28 N, 67 W, represented an area in which the sound channel is unobstructed by the seafloor. This report documents the comprehensive set of environment data taken at Site Alfa in support of the acoustic measurements. The oceanographic environment was, basically very stable throughout the exercise despite its location in a cold-core eddy of the Gulf Stream. Thermometric satellite imagery collected during the exercise quantified the surface temperature within this eddy to be about 1 C cooler than the surrounding waters. The measurements were collected fully within the confines of the eddy, precluding potentially marked variability resulting from acoustic propagation across dissimilar water masses. A 36 hour time series of temperature data collected during the exercise exhibited a maximum sound speed variation of approximately 6 m/sec in the area of the main thermocline below the 18 C water layer. However, a 15 mile displacement over the duration of these measurements precluded an accurate interpretation of this variability. The most profound effect of the eddy on the conduct of the exercise was the extremely strong surface currents experienced. Expendable Current Profile measurements indicate that near surface currents approaching 5.5 kt were present. Plots and tabulations of all data collected during phase Alfa of Broadband-87 are in the appendices.

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