Antarctic Bottom Water Temperature Changes in the Western South Atlantic from 1989–2014

Abstract:

Repeat oceanographic section data in the western South Atlantic taken mostly in 1989 (1995 across the Scotia Sea), 2005, and 2014 are used to quantify warming in abyssal waters that spread northward through the region from their Antarctic origins in the Weddell Sea. While much of the Scotia Sea warmed from 1995–2005, only the southernmost portion, on the north side of the Weddell Gyre, continued to warm from 2005–2014. The abyssal Argentine Basin also warmed from 1989–2005, but again only the southernmost portion continued to warm from 2005–2014, suggesting a slowdown in the inflow of the coldest, densest Antarctic Bottom Waters into the western South Atlantic from 1989–2014. In contrast, the abyssal waters of the Brazil Basin warmed both from 1989–2005 and from 2005–2014, at a rate of about 2 mºC yr^-1. These results, together with findings from previous studies, suggest the deep warming signal observed in the Weddell Sea after the mid-1970s Weddell Polynya was followed by abyssal warming in the Argentine Basin from the late 1970s through about 2005, then warming in the deep Vema Channel from about 1992 through at least 2010, and warming in the Brazil Basin from 1989–2014.