Weddell Sea Bottom Water

Weddell Sea Bottom Water (WSBW) is a subset of Antarctic Bottom Water (AABW) that is at a temperature of -0.7 °C or colder. It consists of a higher salinity branch and a lower salinity branch. It originates in the Weddell Sea and closely follows the sea floor as it flows out into the rest of the world's oceans. It is created mainly due to the high surface winds blowing off the Antarctic continent which helps cool and oxygenate it. It flows at a rate of 2 to 5 Sv and contributes to the overall flow of the AABW.

The Weddell Sea plays an important role in the movement of the world's oceans. An important part of the Weddell Sea is Weddell Sea Bottom Water (WSBW). WSBW is a major contributor to Antarctic Bottom Water (AABW). While WSBW is considered part of AABW, the distinction comes in its potential temperature. The potential temperature of WSBW is -0.7 °C. At this temperature, the potential temperature vs. salinity chart shows a sharp change in slope. The outflow of WSBW is influenced greatly by the Scotia Ridge. The movement of WBSW is listed as 16 Sv which contributes to a total 97 Sv outflow of AABW. 2 to 5 Sv of this production is newly formed bottom water off the Antarctic coast.

The Weddell Sea is characterized by a cyclonic gyre bounded on the south by the Antarctic continent, on the west by the Antarctic Peninsula, on the north by the Scotia Ridge, and extending as far east as 20 to 30°E. The precursor to bottom water formation is derived from the broad continental shelf west of 40°W where brine released during sea-ice formation produces a large reservoir of cold (0 to - 1.8 °C), high salinity (S ≥ 34.62 psu) shelf water. This water mass then mixes with a modified form of Warm Deep Water near the edge of the continental shelf to form a dense layer of bottom water, which in turn sinks along the continental slope and flows cyclonically around the western and northern perimeter of the Weddell Sea basin. Because large quantities of the high salinity water are observed on the continental shelf even during summer, bottom water may form throughout the year.

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