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SUMMARY:The East Greenland Boundary Current System South of Denmark Strait
  - Alex Brearley (National Oceanography Centre\, Southampton)
DTSTART:20120523T100000Z
DTEND:20120523T110000Z
UID:TALK36148@talks.cam.ac.uk
CONTACT:Povl Abrahamsen
DESCRIPTION:Four high-resolution hydrographic sections were occupied acros
 s the East Greenland shelf and slope to the south of Denmark Strait near 6
 5°N in the summer seasons of 2001\, 2003\, 2004 and 2007 respectively\, t
 he 2004 section being aboard RRS James Clark Ross. Each section included u
 se of a vessel-mounted acoustic Doppler current profiler\, allowing the co
 mputation of absolute geostrophic velocities. The boundary current at this
  location comprises the East Greenland/Irminger Current (EGIC) in the uppe
 r layer\, the Deep Western Boundary Current (DWBC) at the base of the cont
 inental slope\, and the East Greenland spill jet\, which resides inshore a
 nd beneath the EGIC. The bottom-intensified spill jet\, first \nobserved o
 nly in 2001\, was seen in every occupation and in the mean transported 4.8
  ± 2.3 Sv equatorward\, which is equivalent to the DWBC at this latitude 
 (4.8 ± 1.2 Sv). The spill jet displayed considerable \nvariability from s
 ection-to-section\, which appeared to be linked to the upper-layer hydrogr
 aphic front that separates warm and salty Atlantic-origin water in the Irm
 inger Basin from the cold and fresh Arctic-origin water on the shelf. When
  this EGIC front is located near the shelfbreak (as in 2001/2003)\, the sp
 ill jet is confined to the outer shelf/upper slope and its transport is sm
 aller. During these times there is less mixing and the water advected by t
 he jet is significantly lighter than that transported by the DWBC. In cont
 rast\, when the EGIC is located seaward of the shelfbreak (as in 2004/2007
 ) the spill jet extends farther down the continental slope and its volume 
 flux is larger. In these instances there is stronger mixing and the spill 
 jet can transport water as dense as the Denmark Strait Overflow Water. Thi
 s strong mixing is in part promoted by the strong horizontal potential vor
 ticity gradients around the Spill Jet\, which in turn drive a number of in
 stability processes including symmetric instability. Differences in the ch
 aracter of the spill jet between each section may represent different stag
 es in the spilling process by which dense water cascades off the shelf sou
 th of Denmark Strait to form the spill jet. These results suggest that the
  spill jet is a permanent feature of the \nsummertime circulation in this 
 region and contributes significantly to the intermediate\, and at times de
 ep\, limb of the Atlantic Meridional Overturning Circulation.
LOCATION:British Antarctic Survey\, Room 330B
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