Seasonal to interannual upper ocean variability in the Drake Passage

• Main Author: Janet Sprintall
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Published: 2003
• Subjects: Within the Southern Ocean; the Antarctic Circ; Antarctic; Drake Passage; Southern Ocean; The Antarctic; Antarc*
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.464.7116; http://www-pord.ucsd.edu/~jsprintall/pub_dir/sprintalljmr.pdf

Year-round monitoring of the upper-ocean temperature variability in Drake Passage has been undertakensince September 1996 through repeat expendablebathythermograph(XBT) surveys. The closely spaced measurements (6–15 km apart) provide the rst multi-year time series for examining seasonal to interannual variability in this Southern Ocean choke point. While the temperature sections reveal the seasonal variability in water mass formation of the upper layer, there was no seasonal signal evident below 200 m. Similarly, there was little seasonal cycle evident in the position of the Subantarctic Front, the Polar Front and the Southern Antarctic Circumpolar Current Front associated with the Antarctic Circumpolar Current (ACC) in Drake Passage. Mesoscale eddy features are readily identi able in the XBT sections and in some sparse salinity sections, as distinct alternating bands separated by near-vertical isotherms of cold and warm core temperatures. The eddies can also be tracked in concurrent maps of altimetric sea surface height, with time scales of;35 days and diameters of 50–100 km, following a north to north-east trajectorywith the main path of ACC ow through Drake Passage. Both the XBT and the altimetric data suggest the eddies are mainly con ned to the Antarctic Polar Frontal Zone. To determine transport, an empirical relation-ship is derived between upper ocean XBT temperature and a baroclinicmass transport function from