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