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SUMMARY:Mixing by meso-scale eddies in the Southern Ocean: two perspective
 s. - Emma Boland\; BAS
DTSTART:20130712T100000Z
DTEND:20130712T110000Z
UID:TALK45826@talks.cam.ac.uk
CONTACT:Dr Andrew Meijers
DESCRIPTION:Quantifying the mixing and stirring caused by meso-scale eddie
 s in the Southern Ocean remains an open problem in physical oceanography. 
 Meso-scale eddies are of first-order importance to the meridional overturn
 ing circulation and to the transport of tracers such as heat\, salt and CO
 2. One of the obstacles to further understanding is the lack of observatio
 ns of this region. Here I will present work from my PhD thesis which used 
 a combination of satellite and in situ observations to diagnose two differ
 ent eddy mixing measures.\n\nThe first is an effective diffusivity\, deriv
 ed for the whole Southern Ocean\, using geostrophic surface velocities fro
 m satellite altimetry to advect a tracer in the offline MITgcm. We find th
 at\, as previously observed\, there is a minimum in mixing in the core of 
 the ACC. This is thought to be due to eddy - mean flow interactions\, and 
 we investigate alternate mixing parametrisations that try to account for t
 his effect.\n\nThe second measure comes from comparing simulations of the 
 DIMES tracer release with measurements taken on the DIMES cruises. Using a
  technique to assess the 'roughness' of a set of tracer values\, we compar
 e various simulations and assess the most appropriate diffusivity to match
  the observations. This leads to an estimate of the mixing experienced by 
 the tracer\, and shows an increasing diffusivity through the Drake Passage
  compared with upstream.
LOCATION:British Antarctic Survey\, Room 330B
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