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SUMMARY:Constraining water mass transformation and overflow dynamics on th
 e Arctic shelves -  Elizabeth Yankovsky (New York University)
DTSTART:20210519T130000Z
DTEND:20210519T140000Z
UID:TALK156295@talks.cam.ac.uk
CONTACT:Dr Irena Vankova
DESCRIPTION:Dense gravity currents forced by surface buoyancy loss over po
 lar continental shelves are important contributors to subsurface and abyss
 al ventilation throughout the World Ocean\, yet remain challenging to obse
 rve and represent accurately in models. The vast\, and rapidly evolving Ar
 ctic shelves are particularly crucial in setting water mass structure of t
 he entire basin and influencing its response to changing climatic conditio
 ns. Observations indicate that some of the strongest water mass transforma
 tion processes in the Arctic occur in the Barents and Kara Sea shelves. Th
 e combination of cooling of warm Atlantic inflow as well as localized poly
 nya development around Svalbard\, Franz Josef Land\, and Novaya Zemlya lea
 ds to development of waters with higher densities than even the deepest la
 yers of the Arctic. Depending on the amount of mixing and strength of the 
 buoyancy forcing\, these dense overflows may also ventilate the Arctic hal
 ocline layer.\n\n \n\nIn the first part of the talk\, I will present ideal
 ized high-resolution simulations aimed at studying the dynamics of rotatin
 g dense overflows. I will discuss the role of mesoscale baroclinic eddies 
 and submesoscale symmetric instability in setting the pathways and propert
 ies of the dense waters. In the second part\, we will examine how modern s
 tate-of-the-art general circulation models presently capture shelf overflo
 w dynamics in the Arctic. We consider: (1) whether dense shelf overflows a
 nd the vertical structure of the Arctic are well-represented by the GFDL-O
 M4 1/4-degree model as well as an analogous 1/8-degree version\; and (2) p
 athways by which overflows and water mass transformation over the Eurasian
  shelves contribute to setting the vertical structure of the interior Arct
 ic. We also explore the changes in ventilation pathways that the Arctic wi
 ll experience as a result of warming. In particular – we see evidence fo
 r dense water formation changing from being influenced by polynyas and bri
 ne rejection as sea ice forms to being predominantly set by cooling of the
  inflowing\, highly saline Atlantic waters.
LOCATION:British Antarctic Survey\, Zoom
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