Accession Number : ADA292749

Title :   Southeast Texas Shelf Environment Off Port Isabel, Texas for the AA2 Exercise.

Descriptive Note : Final rept.,

Corporate Author : NAVAL RESEARCH LAB STENNIS SPACE CENTER MS

Personal Author(s) : Gomes, Bruce R. ; Fulford, James K. ; Cloy, George P.

PDF Url : ADA292749

Report Date : 21 MAR 1995

Pagination or Media Count : 100

Abstract : During the fall of 1993, the Airborne Active Adjunct and Advanced Active Sonobuoy Experiment (AA2) was conducted off Port Isabel, Texas. The shelf in this area is dominated by a 9-m layer of clay with interlayered silts, and sands. Along most of the east-west track there is a strong subbottom reflector at an average of 5 m below the seafloor. Its disappearance coincides with higher clay content. North-south track records indicate the presence of clay sediments with substrata displaying evidence of slumping, faulting, and expressions of ancestral-delta relict-sands. Geoacoustic models are derived from exercise measurements. Oceanographic variability is due to wind induced circulation and interaction of shelf water with Caribbean Subtropical Water. A mixed layer down to 3040 m is present with oscillations in the thermocline. Values for stability in the thermocline are used to compute a Brunt-Vaisala frequency of 0.0045 to 0.0057 Hz for internal waves. Geostrophic current velocities indicate a southwesterly 6-cm/s density driven current at the surface. Wind driven currents ot 10 cm/s alternately reduce or reinforce this geostrophic flow.

Descriptors :   *GEOACOUSTICS, *CONTINENTAL SHELVES, MODELS, INTERACTIONS, LAYERS, SAND, BATHYMETRY, ACOUSTIC MEASUREMENT, CLAY, MIXING, NORTH(DIRECTION), OSCILLATION, ACOUSTIC VELOCITY, SEA WATER, GEOSTROPHIC CURRENTS, SEDIMENTS, TEXAS, OCEAN BOTTOM SOILS, SONOBUOYS, INTERNAL WAVES, THERMOCLINES, ACOUSTIC REFLECTION, OCEANOGRAPHY, SILT, SUBTROPICAL REGIONS, MEXICO GULF, WEST INDIES.

Subject Categories : Geology, Geochemistry and Mineralogy

Distribution Statement : APPROVED FOR PUBLIC RELEASE