Mass and heat exchanges across the Greenland Scotland Ridge and the AMEX budget balance

1. Mass and heat exchanges across the Greenland Scotland Ridgeand the AMEX budget balance from space Heat by winds by ocean currents Steingrímur Jónsson, University of Akureyri & Marine Research Institute Héðinn Valdimarsson, Marine Research Institute, Reykjavik Bogi Hansen, Faroe Marine Research Institute, Tórshavn Karin Margretha H. Larsen, Faroe Marine Research Institute, Tórshavn Barbara Berx, Marine Scotland Science, Marine Laboratory, Aberdeen Toby Sherwin, SAMS, Scottish Marine Institute, Oban Steffen M. Olsen, Danish Meteorological Institute , Copenhagen Kerstin Jochumsen, Institut für Meereskunde, Universität Hamburg DetlefQuadfasel, Institut für Meereskunde, Universität Hamburg Svein Østerhus, Uni Research, Bergen image:AGU 2003 Trieste 10 Oct. 2013

2. Arctic Mediterranean Exchanges AMEX English Channel FSC IFR Denmark Strait Hudson Strait

3. AGU, 2003 Transport (mass and heat) observatories1995-ongoingFrom Bogi’s presentation at the kick-off NACLIM MAIA

4. Tools Current meters (ADCP) Hydrography CTD-sections

6. AGU, 2003 Atlantic inflow volume transport Inflowing Atlantic water (millions m3/second) No trend !!!!!!!!!!!!!!!!!!!!!!!!! No trend No weakening Iceland branch Faroe branch Shetland branch image:AGU 2003

7. Atlantic inflow volume transport Inflowing Atlantic water (millions m3/second) Iceland branch Faroe branch Shetland branch image:AGU 2003

8. Total Atlantic Volume Inflow1997-2011 8.5 Sv (Østerhus et al. 2005) New results 0.7 Sv 7.1 Sv +- 1 Sv Hansen et al. 2010, Jonsson and Valdimarsson 2012, Berx et al. 2013

9. Combining in-situ measurements and altimetry to estimate volume, heat and salt transport variability through the Faroe Shetland Channel Berx, Hansen, Østerhus, K. M. Larsen, T. Sherwin, and K. Jochumsen, (2013).

10. Return flow / overflow Monthly mean net inflow from observations (FSC+IF+DS) and overflow (FBC+DS). Only months where all three (two) inflow (overflow) have been monitored are included. The net exchange is defined where both inflow and overflow are monitored.

11. Volume budget ”Old numbers” ( 1 Sv = 106 m3/s ) 2.5 Sv Q = 8.5 Sv (Østerhus et al. 2005) 6 Sv

12. Volume budget ”New numbers” ( 1 Sv = 106 m3/s ) 2.5 -?Sv Q = 7.1 +- Sv 6 -?Sv assumption: Bering Strait inflow ~ West of Greenland outflow. English Channel ~ NaN

13. Arctic Mediterranean Exchanges English Channel FSC IFR Denmark Strait Hudson Strait

14. AMEX Budget ?

15. Heat Transport Volume transport: Q Heat import = c · Q · ΔT ≈ c · Q · T Temperature: T Cooling: ΔT

16. Atlantic inflow temperature 1950 – 2010 Heat import = c · Q · T Shetland branch Faroe branch Iceland branch

17. Temperature in Atlantic layer at station M1948-2010 Monthly mean Yearly mean

18. The effect of SPG shrinkage (Hakkinen & Rhines, 2004; Hátún et al., 2005) Before 1995 After 1995 Warmer and more saline

19. Observed and simulated gyre index (SSH averaged for 60°W–15°W, 48°N–65°N) Strong 3.0 1.5 0 Weak -1.5 -3.0 Lohman et al. (2009)

20. Weak and StrongGyre index Lohman et al. (2009) Strong 3.0 1.5 • Atlantic Water Temperature in the Nordic Seas (M) 0 Weak -1.5 -3.0

21. Arctic Mediterranean Exchanges English Channel FSC IFR Denmark Strait Hudson Strait

22. Next • Including time series from Bering and David straits • Combining observation and model results • Closing the AMEX budget on down to seasonal / monthly time scale

23. Intensity and seasonality of the ocean exchange system with the Arctic Mediterranean west (a) and east (b) of Greenland. Stacked, monthly averaged contributions 1948-2010 from individual inflow (bottom) and outflow (top) branches are shown including in a) the English Channel (EC) light inflow (grey), Faroe Shetland Channel (FSC) Atlantic inflow (red) and dense, deep outflow (red), the Denmark Strait (DS) Atlantic inflow (green) and dense outflow (green) and the East Greenland Current (EGC) polar water outflow (blue). The net exchange is shown in black (positive for net inflow). In b) the inflow includes the light inflow through Bering Strait (BS) and outflows the polar water in Lancaster Sound (LS) and Nares Strait (NS).

24. Variability of transport estimates of inflow, overflow and outflow from the global model east of Greenland compared against observations. Model values have been bias corrected and only months where observational data exists are included in the annual means Comparison of modeled and observed exchanges for the individual period of observations. For reference, the model average budget is included for the complete 1992-2010.

25. Seasonality and characteristics of observed (black) and modeled (red) exchanges across the GSR. Seasonality (curves) is calculated as the average of monthly composites from available data in the period 1992 to 2012 and for the full model series (dashed). Variability of de-seasoned and de-trended data is illustrated by their distribution.

26. The research leading to these results has received funding from the European Union 7th Framework Programme (FP7 2007-2013), under grant agreement n.308299 NACLIM www.naclim.eu