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SUMMARY:Foehn jets and warming distributions over the Larsen C Ice Shelf\,
  Antarctica - Andrew Elvidge\, University of East Anglia
DTSTART:20141118T140000Z
DTEND:20141118T150000Z
UID:TALK55311@talks.cam.ac.uk
CONTACT:Dr. Pranab Deb
DESCRIPTION:Previously unknown foehn jets have been identified to the east
  of the Antarctic Peninsula above the Larsen C Ice Shelf. These jets and a
 ssociated foehn warming have major implications for the east coast of the 
 AP\, a region of rapid climatic warming and where two large sections of ic
 e shelf have collapsed in recent years.\n\nDuring three foehn events acros
 s the Antarctic Peninsula\, leeside warming and drying is seen in new airc
 raft observations and simulated well by the Met Office Unified Model (MetU
 M) at ~1.5 km grid spacing. In case A weak southwesterly flow and an eleva
 ted upwind inversion characterise a highly non-linear flow regime with upw
 ind flow blocking. The consequent strongly-accelerated downslope flow lead
 s to high amplitude warming (associated with ice shelf melt) in the immedi
 ate lee of the Peninsula. However\, the warming diminishes rapidly downwin
 d\, due to upward ascent of the foehn flow via a hydraulic jump. In case C
  strong northwesterly winds characterise a relatively linear case with lit
 tle upwind flow blocking. There is no hydraulic jump and strong foehn wind
 s reach right across the ice shelf at low level\, mechanically mixing the 
 near-surface levels\, and delivering large sensible heat fluxes to the ice
  shelf resulting in high melt rates. Case B resides somewhere between case
 s A and C in flow regime linearity and leeside response.\n\nThe foehn jets
  – apparent in aircraft observations where available and MetUM simulatio
 ns of all three cases – are mesoscale features (up to 60 km in width) or
 iginating from the mouths of leeside inlets. Through back trajectory analy
 sis they are identified as a type of gap flow. They have cool\, moist sign
 atures due to a weaker foehn effect than in neighbouring regions of calmer
  flow.\n
LOCATION:British Antarctic Survey\, Room 307
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