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SUMMARY:The observed trend in the Southern Annular Mode: is it the ozone h
 ole or is it greenhouse gases? - Howard Roscoe\, BAS
DTSTART:20080129T110000Z
DTEND:20080129T120000Z
UID:TALK9201@talks.cam.ac.uk
CONTACT:Deb Shoosmith
DESCRIPTION:I will present results of multiple regressions of the leading 
 mode of atmospheric variability at southern high latitudes: the Southern A
 nnular Mode (SAM).  It is regressed against indices with large inter-annua
 l variability\, and one of several trend indices in order to determine whi
 ch trend term gives the optimum fit.  There is a significant linear trend 
 in SAM\, but there is a major increase in significance using chlorine from
  CFCs\, and a further increase using the mass deficit of ozone in the ozon
 e hole.  We make no direct attempt to identify cause and effect\, but if t
 he trend is due to human influence then ozone loss is at least 9 times mor
 e likely the principle cause of the trend in SAM than greenhouse gases\, t
 hough a simultaneous contribution from a small linear trend cannot be excl
 uded.  Other evidence is consistent with a stratospheric cause of the trop
 ospheric effect.
LOCATION:British Antarctic Survey\, Room 307
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