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Understanding Variations of Volume & Freshwater Fluxes through CAA:

Understanding Variations of Volume & Freshwater Fluxes through CAA: Potential Application in Projecting Future Changes Youyu Lu, Simon Higginson, Shannon Nudds Bedford Institute of Oceanography, DFO. Arctic-North Atlantic Interaction (from G Holloway). Focusing on NW Atlantic:

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Understanding Variations of Volume & Freshwater Fluxes through CAA:

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  1. Understanding Variations of Volume & Freshwater Fluxes through CAA: Potential Application in Projecting Future Changes Youyu Lu, Simon Higginson, Shannon Nudds Bedford Institute of Oceanography, DFO

  2. Arctic-North Atlantic Interaction(from G Holloway) Focusing on NW Atlantic: • Key for global “conveyor belt” • Freshwater inputs important for deep convection • Two routes: east or west of Greenland – which one is more important?

  3. Monitoring at Key Locations (DFO Involved)

  4. CAA Not Resolved by Climate Models (due to complicated small-scale geometry)

  5. An Approach to Forecasting/Projecting Long-term Changes in CAA • High-resolution simulations – limited duration • Analysis to understand forcing mechanisms • Derive statistical relationship with large-scale forcing • Forecasting/projecting with outputs of large-scale forcing from climate models This combined dynamical + statistical approach can be applied to a wide range of problems

  6. NEMO Configurations: BIO pan-Arctic • Pan-Arctic 18 km grids; also include nested CAA 6 km grids; • Pan-Arctic 6 km • Grid spacing nearly uniform

  7. Validation Example: Sea-ice Drift Model vs Ice Buoy June 1999 December 1999

  8. Sea-ice Drift: Model vs Ice Buoy June 1999 December 1999

  9. Volume Fluxes Through CAA High correlation between BIO 6 km Arctic model & GLORYS v2 global ocean reanalysis

  10. Freshwater Fluxes Through CAA Less correlated than volume flux – due to difference in salinity field. Needs further validation/study.

  11. Mean Fluxes during 1998-2007 Indeed, FW transport from CAA is larger than that from east of Greenland.

  12. What drives Fluxes Through CAA? Upstream influence – wind in Beaufort Sea (Peterson et al)

  13. What drives Fluxes Through CAA? Downstream influence – Sea level in Baffin Bay (McGeehan & Maslowski 2012)

  14. Analysis of 6 km Model: Seasonal Cycle in Barrow Strait Model agrees quite well with obs at southern side

  15. Seasonal Cycle in Davis Strait Clear difference between western & eastern sides

  16. Seasonal Cycle in Fram Strait Clear difference between western & eastern sides

  17. Seasonal Cycles of Volume & FW Fluxes

  18. Further Work • Analyze correlation with forcing • Determine how forcings operate: barotropic or baroclinic processes? • Develop regression models: link flux variations to large-scale forcing

  19. Summary • Model results suggest that freshwater transport though CAA is larger than that from east of Greenland • Two forcing mechanisms (up- & down-stream) have been proposed by previous studies. This analysis suggests that both mechanisms operate – depending on seasons & locations • Understanding mechanisms may help to develop regression models: linking CAA transports to large-scale forcing • This combined dynamical + statistical approach can help climate projection, and is useful for solving a lot of other problems

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