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SUMMARY:Topographic upwelling of Antarctic Bottom Water in the presence of
  deep stratified interfaces - Lois Baker (University of Edinburgh)
DTSTART:20240521T110000Z
DTEND:20240521T113000Z
UID:TALK215767@talks.cam.ac.uk
DESCRIPTION:Co-authors: Ali Mashayek & Alberto Naveira Garabato\nThe lower
  cell of the meridional overturning circulation (MOC) is sourced by dense 
 Antarctic Bottom Waters (AABW)\, which form and sink around Antarctica and
  subsequently fill the abyssal ocean. For the MOC to `overturn'\, these de
 nse waters must upwell via mixing with lighter waters above. Here\, we inv
 estigate the processes underpinning such mixing\, and the resulting water 
 mass transformation\, using an observationally forced\, high-resolution nu
 merical model of the Drake Passage in the Southern Ocean. In the Drake Pas
 sage\, the mixing of dense AABW formed in the Weddell Sea with lighter dee
 p waters transported from the Pacific Ocean by the Antarctic Circumpolar C
 urrent is catalysed by energetic flows impinging on rough topography. We f
 ind that multiple topographic interaction processes facilitate the mixing 
 of the two water masses\, ultimately resulting in the upwelling of waters 
 with neutral density greater than 28.19 kg m-3\, and the downwelling of th
 e lighter waters above. In particular\, we identify the role of sharp dens
 ity interfaces between AABW and overlying waters and find that the dynamic
 s of the interfaces' interaction with topography can modify many of the pr
 ocesses that generate mixing. Such sharp interfaces between water masses h
 ave been observed in several parts of the global ocean\, but are unresolve
 d and unrepresented in climate-scale ocean models. We suggest that they ar
 e likely to play an important role in abyssal dynamics and mixing\, and th
 erefore require further exploration.
LOCATION:Seminar Room 1\, Newton Institute
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