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SUMMARY:Controls on the stability of Greenland’s tidewater glaciers: the
  impact of runoff on fjord circulation and termini melt rates - Tom Cowton
  (University of Sheffield)
DTSTART:20150128T163000Z
DTEND:20150128T173000Z
UID:TALK57473@talks.cam.ac.uk
CONTACT:Poul Christoffersen
DESCRIPTION:Observations suggest that oceanic warming may cause phases of 
 rapid retreat and acceleration at Greenland’s marine-terminating outlet 
 glaciers\, significantly increasing the rate of mass loss from the ice she
 et. In this scenario\, retreat may be triggered by increased submarine mel
 ting at the glacier termini. Due to the inaccessibility of this submarine 
 environment however\, little is known about the rate of melting or how it 
 is influenced by oceanic and atmospheric processes. This seminar will focu
 s on the potential role of meltwater runoff from these glaciers in stimula
 ting submarine melting. Firstly\, a high resolution general circulation mo
 del (MITgcm) is used to explore the role of near-terminus hydrology on sub
 marine melt rate. It has been shown previously that freshwater input incre
 ases melting by driving a vigorous upwelling circulation\; we find that th
 e importance of this process is strongly dependent on the subglacial drain
 age morphology\, with more distributed drainage systems driving dramatical
 ly higher melt rates. We then explore the influence of glacial runoff on t
 he wider circulation of the fjords. Through simulation of Kangerdlugssuaq 
 Fjord\, east Greenland\, we find that this freshwater input drives a stron
 g\, two-celled overturning circulation capable of transporting warm ocean 
 waters to the fjord head on sub-seasonal timescales. This circulation may 
 play a significant role in maintaining the connection between the ocean an
 d the ice sheet\, permitting glaciers to respond rapidly to changing ocean
  properties despite long and complex fjord systems.
LOCATION:Scott Polar Research Institute\, main lecture theatre
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