Water masses and circulation patterns in the region of the Blake-Bahama outer ridge

• DOI: 10.1016/0011-7471(71)90106-9
• Publication Date: 2003-08-06T15:17:55Z
• Authors: Anthony F. Amos; Arnold L. Gordon; Eric D. Schneider
• Keywords: 13. Climate action; 14. Life underwater; 01 natural sciences; 0105 earth and related environmental sciences

Abstract The water masses and circulation patterns of the Blake-Bahama Outer Ridge area of the western North Atlantic were studied using a salinity/temperature/depth (STD) recording system. The dynamic method was applied to STD data in the deep ocean, revealing that the Western Boundary Undercurrent (WBUC) flows with velocities up to 26 cm sec−1 at the bottom on the eastern flank of the Outer Ridge. The volume transport was computed to be 22 × 106 m3/sec. The high Antarctic Bottom Water (AABW) content (up to 20%) of this current suggests that AABW flowing north into the western North Atlantic Basin is deflected by the ocean basin hills, at about 35°N merges with North Atlantic Deep Water (NADW), and returns southward along the eastern continental margin. The computed velocities and directions confirm that the WBUC in this area is a contour-following current. A layer of cold isothermal water 20–170 m thick was found on the bottom over much of the section at depths ranging from 3800 to 5400 m. In some locations the layer was capped by a comparatively steep thermal gradient. The higher AABW content of this homogeneous stratum may be a result of the confluence of NADW and AABW. The possibility that a lower turbulent boundary layer exists in the deep ocean, whose velocity field is dependent on bottom roughness, is also examined by applying relationships derived from similar phenomena in the lower atmosphere.