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Annular Variability and Change
John C. Fyfe
Canadian Centre for ClimateModelling and Analysis
Acknowledging
• Boer and Flato
• Monahan, Ambaum, Stephenson, North, Lorenz and Teng
• Saenko, Zickfeld, Eby, Spence, Montenegro, Weaver, England and Stone
Arctic Oscillation
Arctic Oscillation
Antarctic Oscillation
• Model has realistic annular modes, with positive trends under forced change
• Model does not suggest stratospheric involvement
Conclusions
Main Directions Since 1999
• Improving our basic understanding of the annular modes
• Assessing the impact of annular trends on the Southern Ocean
Analog Device for Climate Change
Climate Variability in the Past
Climate Variability in the Future
X
The Southern OceanAnt
arct
ica
Antarctic Oscillation
ZonalWindStress
ACC
Böning et al., Nature Geoscience, 2008
Winds Strengthen
Isopycnals Steepen
Eddies Strengthen
Isopycnals Flatten
But eddies arenot resolved in GCMs
ACC Transport with Resolution
55ºS
Ant
arct
ica
CO2
uptake
DIC removal
CO2
outgassing
DIC
sup
ply
westerlies
Human CO2
emissions
Air-to-Sea Flux of CO2
Out
gas
Upt
ake
Le Quére et al., Science, 2008
Adapted from Gille, Science, 2002
Conclusions
• Models predict intensifying ACC
• Models predict more carbon uptake
• Warming is attributed to human activity
Annular Variability and Change
John C. Fyfe
Canadian Centre for ClimateModelling and Analysis