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SUMMARY:Impacts of iceberg capsize-induced sudden ocean mixing on fjord ci
 rculation and glacier melt - Oscar Tovey Garcia (Univ. Oxford)
DTSTART:20260211T130000Z
DTEND:20260211T140000Z
UID:TALK242980@talks.cam.ac.uk
CONTACT:Emma
DESCRIPTION:The Greenland Ice Sheet loses roughly half of its mass by ice 
 discharge at marine terminating glaciers. Some of the largest and fastest 
 flowing glaciers around Greenland calve kilometre-scale icebergs into long
 \, narrow and deep fjords. These enormous icebergs typically capsize\, or 
 “flip” into more gravitationally stable orientations\, and in doing so
  are thought to vigorously mix the stratified ocean within a small region 
 in front of the glacier front.\nWe investigate the effect of sudden ocean 
 mixing events on flow within an idealised\, linearly-stratified model fjor
 d using the Oceananigans.jl nonhydrostatic model. A large fraction of the 
 available potential energy is rapidly converted to kinetic energy and radi
 ates away as internal waves. These internal waves produce pulses of elevat
 ed melt rate across the entire glacier front\, with magnitudes comparable 
 to melt rates due to subglacial discharge plumes. On longer timescales\, t
 he qualitative character of the response depends on the ratio of fjord wid
 th\, W\, to first baroclinic Rossby deformation radius\, R. Typical Greenl
 and fjords have W/R between 0.5 and 2.0. Within this range of W/R\, our mo
 del predicts the appearance of a long-lived nearly geostrophic anticycloni
 c eddy spanning the entire width of the fjord\, constrained to mid-depths\
 , in front of the glacier terminus. This eddy drives a sustained melt anom
 aly at mid-depths for many days\, which may promote undercutting. We also 
 investigate sensitivity to the horizontal extent of the region over which 
 the fluid is mixed\, and find that increasing the mixed volume beyond some
  critical value destabilises the abovementioned eddy\, leading to its brea
 k up and consequently reducing the predicted glacier melt rate.
LOCATION:MR12
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