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SUMMARY:The impact of lee waves on the Southern Ocean circulation and its 
 response to winds - Luwei Yang\, University of California\, Los Angeles
DTSTART:20201104T150000Z
DTEND:20201104T160000Z
UID:TALK150724@talks.cam.ac.uk
CONTACT:Dr. Shenjie Zhou
DESCRIPTION:Observations and idealized numerical simulations suggest that 
 enhanced turbulent energy dissipation and mixing in the Southern Ocean are
  modulated by the transient eddy field through the generation and breaking
  of lee waves at rough topography. Lee waves have been shown to extract a 
 significant amount of energy from the transient eddy field through the wor
 k done by lee wave drag against bottom flow. In this study\, we investigat
 e how lee waves affect the Southern Ocean circulation and its sensitivity 
 to wind stress using an idealized\, eddy-resolving model of the Southern O
 cean and an energetically consistent lee wave drag and mixing parameteriza
 tion. \n\nOur results show that adding lee waves to the model increases th
 e baroclinic volume transport of the Antarctic Circumpolar Current (ACC) a
 nd also have a significant impact on the lower overturning circulation and
  deep stratification. The changes induced by lee wave drag can be explaine
 d by the eddy kinetic energy (EKE) balance\, in which the EKE dissipation 
 by lee wave drag is compensated by the enhanced EKE generation through bar
 oclinic instability of the ACC. The lee-wave-driven mixing plays a minor r
 ole in modulating the ACC transport but makes a significant impact on the 
 lower overturning circulation and deep stratification. We also find that l
 ee waves significantly alter the sensitivity of the baroclinic ACC transpo
 rt and lower overturning circulation to wind stress. Our results show that
  the drag and mixing effects of lee waves are coupled through bottom strat
 ification and bottom kinetic energy. The coupling leads to a nonlinear com
 bination of the individual effects of drag and mixing. Our results suggest
  that the drag and mixing effects of lee waves should be parameterized sim
 ultaneously in global ocean models to properly represent the impact of lee
  waves on the Southern Ocean circulation.\n
LOCATION:British Antarctic Survey\, Zoom
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