Warming of the deep water in the Weddell Sea along the Greenwich meridian: 1977-2001

The Weddell Deep Water (WDW) warmed substantially along the Greenwich meridian following the Weddell Polynya of the 1970s. Areas affected by the polynya contained similar to14GJ/m(2) more heat in 2001 than in 1977. This warming would require a flux of similar to390 W/m(2) if it were to take place over a year. Large variations in heat content of the WDW are found between the Antarctic coast and Maud Rise (64degreesS). The small variation found north of Maud Rise is opposite in phase to that to the south, and the warming was close to monotonic south of 68degreesS. The mean warming of WDW along the section is similar to0.032degreesC per decade, comparable to the warming of the Antarctic Circumpolar Current. The mean warming compares with a surface heat flux of 4 W/m(2) over the 25 year period, an order of magnitude higher than the warming of the global ocean. As variation in mean salinity of the WDW follows the warming/cooling events, variation in inflow probably explains a cooling event between 1984 and 1989, and a warming event between 1989 and 1992. Cooling during the late 1990s is probably related to the reappearance of a polynya like feature in some winter months as an area 100km in diameter close to Maud Rise with 10-20% lower sea ice concentrations than the Surrounding ocean. (C) 2004 Elsevier Ltd. All rights reserved.