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SUMMARY:Modelling Submesoscale Dynamics: A new parameterization for symmet
 ric instability - Dr. Scott Bachman\, University of Cambridge
DTSTART:20150902T130000Z
DTEND:20150902T140000Z
UID:TALK59735@talks.cam.ac.uk
CONTACT:Dr Dave Munday
DESCRIPTION:Next-generation ocean models are expected to routinely resolve
  dynamics at 1/4 degree or smaller\, offering new challenges in modelling 
 subgridscale physics. These models are entering a regime where the unresol
 ved turbulence is less constrained by planetary rotation\, requiring a par
 adigm shift in the way modellers construct turbulence closures. Of particu
 lar importance is the representation of submesoscale turbulence\, occupyin
 g O(1-10) km scales\, which plays a leading role in setting the stratifica
 tion of the surface mixed layer and mediating air-sea fluxes. This talk wi
 ll introduce the submesoscale parameterization problem by presenting a few
  extant parameterizations\, and will focus on a special type of fluid inst
 ability for which no parameteriation has previously been developed: symmet
 ric instability (SI). The theory and dynamics of SI will be discussed\, fr
 om which a new parameterization will be proposed. This parameterization is
  dependent on external forcing by either surface buoyancy loss or down-fro
 nt winds\, which reduce potential vorticity (PV) and lead to conditions fa
 vorable for SI. Preliminary testing of the parameterization using a set of
  idealized models shows that the induced vertical fluxes of passive tracer
 s and momentum are consistent with those from SI-resolving Large Eddy Simu
 lations.\n
LOCATION:British Antarctic Survey\, Room 307
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