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SUMMARY:A new mechanism for ocean-atmosphere coupling in midlatitudes - Ar
 naud Czaja (Imperial College London)
DTSTART:20110126T110000Z
DTEND:20110126T120000Z
UID:TALK27415@talks.cam.ac.uk
CONTACT:Povl Abrahamsen
DESCRIPTION:After reviewing the role of the extra-tropical oceans in shapi
 ng climate variability\, the role of moist convection in "transferring" up
 ward surface ocean conditions throughout the troposphere will be analyzed 
 in reanalysis data for the Northern and Southern extra-tropical Hemisphere
 s in winter.\n\nConditions for the development of a convective air column 
 from the sea surface to the tropopause are found to be met frequently over
  all major western boundary currents and their extension in the oceanic in
 terior (sometimes by as much as 50% of the time). These large occurences a
 re shown to be jointly controlled by oceanic advection of warm waters and\
 , on the atmospheric side\, by the downward displacement of the tropopause
  associated with synoptic weather systems.\n\nBased on these results\, it 
 is proposed that the oceans can influence the atmosphere directly through 
 convection in midlatitudes\, as is commonly thought to occur in the Tropic
 s. Analysis of the Richardson number Ri found at low levels suggest that m
 oist symmetric instability (0 < Ri < 1)  is a key process involved in link
 ing surface ocean temperatures to atmospheric lapse-rates\, in addition to
  standard upright convection. These low Ri processes are not currently par
 ameterized in climate models\, which raises the possibility that the extra
 -tropical oceanic influence on climate might be underestimated in the curr
 ent generation of models.
LOCATION:British Antarctic Survey\, Room 330B
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