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SUMMARY:Saturation and compensation: Southern Ocean circulation in CMIP5 m
 odels - Stephanie Downes\, Australian National University
DTSTART:20130131T110000Z
DTEND:20130131T120000Z
UID:TALK43078@talks.cam.ac.uk
CONTACT:Dr Andrew Meijers
DESCRIPTION:We use thirteen climate models from the Coupled Model Intercom
 parison Project Phase 5 (CMIP5) to evaluate the response of the Antarctic 
 Circumpolar Current (ACC) transport and Southern Ocean meridional overturn
 ing circulation to surface wind stress and buoyancy changes. The circulati
 on responses of these coarse resolution coupled models to surface buoyancy
  fluxes are compared with the theoretical wind-based predictions of eddy s
 aturation (where the ACC transport is insensitive to increased surface win
 d stress) and eddy compensation (where eddies balance the increased wind-d
 riven Eulerian overturning circulation). The change in the eddy induced ov
 erturning in both depth and density space is quantified. Under a future CM
 IP5 climate pathway the models robustly project reduced Southern Ocean den
 sity in the upper 2000~m accompanied by strengthened stratification. Despi
 te an overall increase in overlying wind stress\, the projected ACC transp
 orts lie within  15% of their historical state\, and no significant relati
 onship with changes in the magnitude or position of the wind stress is ide
 ntified. The models project a strong increase in the surface heat and fres
 hwater fluxes that weaken the ACC transport at the end of the 21st century
 . In contrast\, the surface buoyancy flux changes in the northern half of 
 the ACC region and the wind-driven surface transports are significantly co
 rrelated with an increased upper and decreased lower Eulerian mean meridio
 nal overturning circulation. \n
LOCATION:British Antarctic Survey\, Room 330B
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