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SUMMARY:A conceptual model of ocean heat uptake under climate change - Pro
 f. David Marshall\, University of Oxford
DTSTART:20150325T140000Z
DTEND:20150325T150000Z
UID:TALK53921@talks.cam.ac.uk
CONTACT:Dr Alexander Brearley
DESCRIPTION:A conceptual model of ocean heat uptake is developed. The role
 s of Southern Ocean Ekman and eddy transports\, North Atlantic Deep Water 
 (NADW) formation\, and diapycnal mixing in controlling ocean stratificatio
 n and transient heat uptake are investigated under climate change scenario
 s\, including imposed surface warming\, increased Southern Ocean wind forc
 ing\, with or without eddy compensation\, and weakened meridional overturn
 ing circulation (MOC) induced by reduced NADW formation. With realistic pr
 ofiles of diapycnal mixing\, ocean heat uptake is dominated by Southern Oc
 ean Ekman transport and its long-term adjustment controlled by the Souther
 n Ocean eddy transport. The time scale of adjustment setting the rate of o
 cean heat uptake increases with depth. For scenarios with increased Southe
 rn Ocean wind forcing or weakened MOC\, deepened stratification results in
  enhanced ocean heat uptake. In each of these experiments\, the role of di
 apycnal mixing in setting ocean stratification and heat uptake is secondar
 y. Conversely\, in experiments with enhanced diapycnal mixing as employed 
 in ‘‘upwelling diffusion’’ slab models\, the contributions of diap
 ycnal mixing and Southern Ocean Ekman transport to the net heat uptake are
  comparable\, but the stratification extends unrealistically to the sea fl
 oor. The simple model is applied to interpret the output of an Earth syste
 m model\, the Second Generation Canadian Earth System Model\, in which the
  atmospheric CO2 concentration is increased by 1% per year until quadrupli
 ng. It is found that Southern Ocean Ekman transport is essential to reprod
 uce the magnitude and vertical profile of ocean heat uptake.
LOCATION:British Antarctic Survey\, Room 307
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