Modification and pathways of Southern Ocean deep waters in the Scotia Sea

• Published in: Deep Sea Research Part I: Oceanographic Research Papers
• Main Authors: Naveira Garabato, A.C., Heywood, K.J., Stevens, D.P.
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: 2002
• Subjects: Antarctic; Antarctic Peninsula; Chasm; Drake Passage; Georgia Basin; Georgia Rise; Northeast Georgia Rise; Pacific; Scotia Sea; South Sandwich Trench; South Scotia Ridge; Southern Ocean; The Antarctic; Weddell; Weddell Sea; Antarc*
• Online Access: https://eprints.soton.ac.uk/37551/

An unprecedented high-quality, quasi-synoptic hydrographic data set collected during the ALBATROSS cruise along the rim of the Scotia Sea is examined to describe the pathways of the deep water masses flowing through the region, and to quantify changes in their properties as they cross the sea. Owing to sparse sampling of the northern and southern boundaries of the basin, the modification and pathways of deep water masses in the Scotia Sea had remained poorly documented despite their global significance. Weddell Sea Deep Water (WSDW) of two distinct types is observed spilling over the South Scotia Ridge to the west and east of the western edge of the Orkney Passage. The colder and fresher type in the west, recently ventilated in the northern Antarctic Peninsula, flows westward to Drake Passage along the southern margin of the Scotia Sea while mixing intensely with eastward-flowing Circumpolar Deep Water (CDW) of the antarctic circumpolar current (ACC). Although a small fraction of the other WSDW type also spreads westward to Drake Passage, the greater part escapes the Scotia Sea eastward through the Georgia Passage and flows into the Malvinas Chasm via a deep gap northeast of South Georgia. A more saline WSDW variety from the South Sandwich Trench may leak into the eastern Scotia Sea through Georgia Passage, but mainly flows around the Northeast Georgia Rise to the northern Georgia Basin. In Drake Passage, the inflowing CDW displays a previously unreported bimodal property distribution, with CDW at the Subantarctic Front receiving a contribution of deep water from the subtropical Pacific. This bimodality is eroded away in the Scotia Sea by vigorous mixing with WSDW and CDW from the Weddell Gyre. The extent of ventilation follows a zonation that can be related to the CDW pathways and the frontal anatomy of the ACC. Between the Southern Boundary of the ACC and the Southern ACC Front, CDW cools by 0.15 C and freshens by 0.015 along isopycnals. The body of CDW in the region of the Polar Front splits after overflowing ...