BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Talks.cam//talks.cam.ac.uk//
X-WR-CALNAME:Talks.cam
BEGIN:VEVENT
SUMMARY:The response of the Meridional Overturning Circulation and Antarct
 ic Circumpolar Current to changes in surface forcing - Callum Shakespeare\
 , DAMTP\, University of Cambridge
DTSTART:20130425T103000Z
DTEND:20130425T113000Z
UID:TALK44543@talks.cam.ac.uk
CONTACT:Catherine Pearson
DESCRIPTION:The ocean stratification and circulation is largely controlled
  by surface fluxes of heat\, water and momentum. Understanding the respons
 e of the ocean\nto changes in the distribution and magnitudes of these for
 cing fields is vital to predictions of future climatic changes\, given the
  role of the\nMeridional Overturning Circulation (MOC) in the poleward tra
 nsport of heat and the importance of the deep ocean as a sink of anthropog
 enic carbon\ndioxide.\n\nI  will discuss the stratification and circulatio
 n of an idealised pole-to-pole ocean basin with a circumpolar channel \, f
 orced by surface wind\nstresses and buoyancy fluxes. Firstly\, the phenome
 na relevant to the maintenance of the MOC in such a basin\, namely boundar
 y currents\, baroclinic\neddies and their parameterisation\, Ekman transpo
 rt and vertical diffusion\, will be reviewed and combined into a simple co
 nceptual model of the ocean\ncirculation. This new model resolves some of 
 the problems associated with previous models  such as Gnanadesikan (1999).
  The model predicts simple\nscaling laws for the response of the ocean str
 atification and overturning circulation to changes in the air-sea fluxes o
 f buoyancy and momentum. The key result is that both buoyancy and wind for
 cing are equally important in\ndetermining the circulation and stratificat
 ion of the ocean basin. The effect of the surface buoyancy fluxes in modif
 ying the ocean stratification\,\nand thus via thermodynamic balance modify
 ing the ocean circulation\, has not been previously quantified.\n\nSecondl
 y\, I present results from a high resolution numerical simulation of the s
 ame idealised ocean basin. These results show good agreement with the\npre
 dictions of the simple conceptual model. Furthermore\, an analysis of the 
 energy budget of the numerical model demonstrates a positive feedback\nbet
 ween the wind and buoyancy forcings. Changes in the rate of generation of 
 available potential energy (APE) by buoyancy fluxes at the ocean surface a
 re\npositively correlated with changes in the rate of generation of kineti
 c energy (KE) by wind stress\, and vice versa. This result emphasises that
  the\noverturning circulation is the result of a complex and subtle balanc
 e of surface forcing mechanisms.
LOCATION:Open Plan Area\, BP Institute\, Madingley Rise CB3 0EZ
END:VEVENT
END:VCALENDAR