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SUMMARY:Ice-ocean interactions in Kangerdlugssuaq Fjord - Dr Poul Christof
 fersen\, Scott Polar Research Institute
DTSTART:20120125T163000Z
DTEND:20120125T173000Z
UID:TALK33997@talks.cam.ac.uk
CONTACT:Steven Palmer
DESCRIPTION:The Greenland Ice Sheet is losing mass at an accelerating pace
 . This decline in mass is a result of increased runoff during longer and w
 armer summers as well as the interaction of the ice sheet with the surroun
 ding seas. Whereas the effect of atmospheric warming is relatively well es
 tablished\, little is known about the latter effect since ice-ocean intera
 ctions in glaciated fjords are poorly documented. Here\, we use hydrograph
 ic data acquired in Kangerdlugssuaq Fjord and adjacent seas in 1993 and 20
 04\, together with reanalysis from the Nucleus for European Modelling of t
 he Ocean (NEMO)\, to establish the connection between water mass change in
  the fjord and offshore air-sea interactions. The hydrographic data show t
 hat the fjord contains warm subtropical waters and that fjord waters in 20
 04 were considerably warmer than in 1993. The ocean reanalysis shows that 
 the warm properties of fjord waters in 2004 are related to a major peak in
  oceanic shoreward heat flux into a cross-shelf trough on the outer contin
 ental shelf. The heat flux into this trough varies according to seasonal e
 xchanges with the atmosphere as well as from deep seasonal intrusions of s
 ubtropical waters. Both mechanisms contribute to high (low) shoreward heat
  flux when winds from the northeast are weak (strong). The combined effect
  of surface heating and inflow of subtropical waters is seen in the hydrog
 raphic data\, which were collected after periods when along-shore coastal 
 winds from the north were strong (1993) and weak (2004). The latter data w
 ere furthermore acquired during the early phase of a prolonged retreat of 
 Kangerdlugssuaq Glacier. We show that coastal winds vary according to a la
 rge scale pressure gradient defined by a semi-permanent atmospheric high-p
 ressure system over Greenland and a persistent atmospheric low situated ne
 ar Iceland\, i.e. the Icelandic Low\, which defines the northern state of 
 the North Atlantic Oscillation. The magnitude of this pressure gradient is
  controlled by longitudinal variability in the position of the Icelandic L
 ow.
LOCATION:Scott Polar Research Institute\, main lecture theatre
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