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SUMMARY:Comparing the formulations of CCAM and VCAM and their performance 
 as atmospheric GCMs - John McGregor\,   (CSIRO Marine and Atmospheric Rese
 arch (CMAR))
DTSTART:20120928T085000Z
DTEND:20120928T091500Z
UID:TALK40241@talks.cam.ac.uk
CONTACT:Mustapha Amrani
DESCRIPTION:Two cube-based atmospheric GCMs have been developed at CSIRO\,
  the Conformal-Cubic Atmospheric Model (CCAM) and\, more recently\, the Va
 riable Cubic Atmospheric Model (VCAM). The formulations of the dynamical c
 ores of both models will be described and compared. CCAM is formulated on 
 the conformal-cubic grid\, whereas VCAM is cast on the equiangular gnomoni
 c-cubic grid. CCAM is a 2-time-level semi-Lagrangian semi-implicit Euleria
 n model\, whereas VCAM employs a split-explicit flux-conserving approach. 
 Both models use reversible staggering for the wind components (McGregor\, 
 MWR\, 2005) to produce good wave dispersion behavior. CCAM employs several
  orographic treatments that are not available for use in the VCAM dynamica
 l core\, with the interesting consequence that only VCAM requires hybrid v
 ertical coordinates. \n\nBoth models include the same efficient message-pa
 ssing framework. Although VCAM avoids the message-passing overheads necess
 itated by the Helmholtz solver of CCAM\, if does have some overheads from 
 more frequent calls to the wind staggering/unstaggering routines. \n\nAspe
 cts of the climatologies of both models will be compared and their overall
  advantages and disadvantages discussed. VCAM is presently being coupled t
 o the Parallel Cubic Ocean Model (PCOM) from JAMSTEC\; both the atmosphere
  and ocean model employ identical grids\, and progress on this activity wi
 ll be briefly presented. \n\n
LOCATION:Seminar Room 1\, Newton Institute
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