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SUMMARY:The HUB and Bathymetric Control Of Warm Water Inflow To Antarctic 
 Ice Shelf Grounding Lines - Garrett Finucane\, UCLA
DTSTART:20230405T140000Z
DTEND:20230405T150000Z
UID:TALK199069@talks.cam.ac.uk
CONTACT:Dr Michael Haigh
DESCRIPTION:Across Antarctica ice shelves are losing mass at drastically d
 ifferent rates. Estimates suggest 55% of this ablation is due to basal mel
 ting within the ice shelf cavity\, most of this by relatively warm Circump
 olar Deep Water (CDW). Previous studies have suggested that the elevation 
 of CDW is of primary importance in determining the heat transport into ice
  shelf cavities\, and that the CDW temperature maximum has been shallowing
  in recent decades. However a general understanding of the relationship be
 tween the geometry of an ice shelf cavity\, the offshore properties of CDW
 \, and ice shelf melt remains lacking. In this study we investigate these 
 relationships using MITgcm simulations of oceanic melt in an idealized ice
  shelf cavity geometry\, and using observed melt rates beneath Antarctica
 ’s ice shelves.\n \nTo the extent that CDW inflow is buoyancy-driven\, i
 t should be driven by the horizontal baroclinic pressure gradient\, which 
 is related to by the elevation of the CDW layer relative to an ice shelf
 ’s bathymetry. To quantify the extent to which bathymetry obstructs CDW 
 access to geometrically complex ice shelf cavities\, we present a metric c
 alled the Highest Unconnected isoBath (HUB) that captures the elevation th
 at CDW must reach before it may be expected to access the grounding line a
 nd induce melt. We find that the elevation of offshore CDW relative to the
  HUB closely predicts the melt rate across a suite of simulations with a w
 ide range of quasi-randomized geometries. Computing this metric using obse
 rved Antarctic bathymetry and hydrography similarly explains much of the v
 ariance in the observed melt rates of Antarctic ice shelves\, with various
  deviations that likely result from observational uncertainties and local 
 influences of wind and buoyancy forcing over the continental shelf. These 
 findings provide a generalized theoretical grounding for melt resulting fr
 om buoyancy-driven CDW access to Antarctic ice shelf cavities.\n
LOCATION:BAS Seminar Room 1\; https://ukri.zoom.us/j/96200879096
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