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A data-model comparison study of the Arctic Ocean's response
to atmospheric mode of variability
Bruno Tremblay Robert Newton Peter Schlosser
Lamont Doherty Earth Observatory of Columbia University
Acknowledgment: NSF, A. Weaver – M Eby
Introduction
Summer and winter changes in the thermocline
Hypothesized that these changes may also be present on longer time scale
Hunkins and Whiteheads tank experiments read that paper
Tide gauge (PSMSL) data
Tide gauge locations
Do they vary together or not?
Introduction continued
TG time serie + regime shift of the mid 70's; show how it is present in TG and SLP time series
Local to the chukchi sea or arctic wide?
Show how TG correlates with slp, vorticity...
Is it an inverted barometer effect or a large-scale dynamic effect?
Subtract the inverse barometer effect
Introduction continued
Uvic-ESCM ocean model 1.8 x 3.6 x 19level
Disclaimer, problem with mean climate
Ice area and volume export from Uvic (validation)
Liquid fresh water outflux, and how it correlated with slp, and vorticity
Total fresh water content of Arctic Ocean, how it correlates with vorticity input and arctic regimes
How Total FW content correlated with FW flux
Introduction continued
Aagaard and Caarmaack: Ice export : 2790 km3/year Water export : 1160 km/year
Meredith et al: water export might be much larger.
Introduction continued
Tank experiment
Tidal gauge station (PSMSL)
SSH – Inverse barometer effectJan 1, 1949
Sea surface height anomaly (norm)
Sea surface height anomaly
TG data and Atm indices
March SIC and thicknes
Fram Ice Area Flux
Fram Ice Area Flux – NAO
Fram Ice Volume Flux
Fram Ice Volume Flux – NAO
Regime shift – mid 70'sHilmer and Jung
SLG – NAO
EOF1 – FM SLP1977-1999
FW content -- SLP
FW content – NAO
FW flux – SLP
FW flux – FW content
Conclusions
Ice export goes with NAO (recently)
Water export goes with NAO as well
Water export is not linked with FW content of Arctic
FW content of arctic goes with SLP or vorticity presumably due to increase ice formation during lower pressure in arctic
Expect a more complicated link between FW content and export when the FW export is more in line with real thing
Conclusions
Longer term FW content changes are larger than seasonal changes
They account for x km3/year compared with y km3 /year for ice export
Future work
• Experiment with the wind forcing to get the proper surface water export
• Dye river and other source of fresh water to break it into component