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Arctic Ocean Dense Water Formation and Heat Transport Study by Ursula Schauer - Key Findings

Explore Ursula Schauer's research on Arctic Ocean circulation, dense water formation, and heat transport. Learn about the impact of salinity changes, heat loss, and entrainment on deep ocean processes. Discover important insights into oceanic heat transport estimates and variability. Gain knowledge about synoptic observations and key processes in the Arctic Ocean under changing climate conditions.

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Arctic Ocean Dense Water Formation and Heat Transport Study by Ursula Schauer - Key Findings

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  1. How much does the dense water formation in the Arctic Ocean contribute to the overflow? • Will an increased salinity of the inflow compensate a larger runoff and a warmer climate and maintain the possibility of dense water formation on the shelves? • How important are entrainment and heat loss to the deep? • (Ursula Schauer)

  2. About sense and nonsense of oceanic heat transport estimates -1,8 °C Ursula Schauer, AWI -35°C Storfjord, März 2003

  3. DAMOCLES – „Description of Work“ Project objectives “... ... 3. Synoptic observation of the Arctic Ocean circulation and key processes An observational system ... ... ... New techniques will be used to assess synoptically the state of the ocean under the ice and the fluxes of heat, salt and volume across the boundaries. ... ...”

  4. U. Schauer during ASOF conference in Torshavn, 29 June 2006: What progress did we make since pre-ASOF times? Pre-ASOF: Estimates of oceanic northward heat flux between 18 TW (Rudels, 1987) and 67 TW (Aagaard & Greisman, 1975) (as recompiled by Simonsen and Haugan, 1996) Variability unknown. Flow has a strong barotropic component and seasonal signal (e.g. Hanzlick, 1983) i.e. baroclinic calculations from summer surveys not suitable for transport estimates 3 flow branches: along the shelf edge, along the Yermak Plateau and recirculation i.e. we need appropriate horizontal resolution

  5. Monthly mean volume and heat transport through Fram Strait northward southward net Volume transport net mean: -2.1 Sv stdev: 5.9 Sv net mean: -1.6 Sv stdev: 2.5 Sv 1998 2005 Heat transport net mean: 29 TW stdev: 20 TW net mean: 47 TW stdev: 15 TW Tref=-0.1°C

  6. Oceanic heat transport 1. The physical concept of oceanic heat transport is only reasonable in its ability to add heat to or take away heat from a defined ocean volume. 2. Therefore oceanic heat transport calculated from measurements at the boundary are only meaningful when the entire boundary is taken into account. 3. That is also true for temporal variations of oceanic heat transports.

  7. Oceanic heat transport 2. Therefore oceanic heat transport calculated from measurements at the boundary are only meaningful when the entire boundary is taken into account. Heat transport through Fram Strait Tref = outflow temperature? 0°C? -2°C? absolute zero? … Well – anyway we only want to compare different branches and changes …

  8. year 1 Change in FS inflow temperature year 2

  9. year 1 Change in FS inflow and BSO outflow year 2

  10. Change in FS inflow and BSO outflow

  11. year 1 Change in FS inflow and outflow year 2

  12. Change in FS inflow and outflow

  13. Oceanic heat transport • 1. The physical concept of oceanic heat transport is only resonable in its ability to add heat to or take away heat from a defined ocean volume. • 2. Therefore oceanic heat transport calculated from velocity and temperature measurements at the boundary are only meaningful when the entire boundary is taken into account. • 3. That is also true for temporal variations of oceanic heat transports. • 4. Contributions by individual passages or branches of flow can not be derived individually by refering the measured temperature to • 0° C • absolute zero (-273°C) • any other arbitrarily chosen reference temperature • an average outflow/inflow temperature 5. Variable oceanic heat transports through individual passages or branchesmust be referred to the current temperature of the compensating in/outflow. Everything else is nonsense!

  14. Monthly mean volume and heat transport through Fram Strait northward southward net Volume transport net mean: -2.1 Sv stdev: 5.9 Sv net mean: -1.6 Sv stdev: 2.5 Sv 1998 2005 Heat transport net mean: 29 TW stdev: 20 TW net mean: 47 TW stdev: 15 TW Tref=-0.1°C

  15. Volume balance – example Inflows: Barents Sea 2.2 Sv Bering Strait 0.8 Sv Freshwater 0.2 Sv Outflows: Fram Strait – 0.6 Sv (mean from ASOF array) Canadian Arctic Archipelago – 1.5 Sv? Arctic Ocean Area 10 x 1012 m2→ 1 Sv net inflow imbalance leads to a sea level increase of 0.25m in 1 month. which is probably as long as such an imbalance may persist. If it is an imbalance? Can the Canadian Arctic Archipelago sustain an outflow of – 2.5 Sv? Bert Rudels, ASOF conference Torshavn:

  16. Monthly mean volume and heat transport through Fram Strait northward southward net ? ? ? Volume transport net mean: -2.1 Sv stdev: 5.9 Sv net mean: -1.6 Sv stdev: 2.5 Sv 1998 2005 Heat transport net mean: 29 TW stdev: 20 TW net mean: 47 TW stdev: 15 TW Tref=-0.1°C

  17. Heat flux through Barents Sea Opening and Svinøy section heatfluks Mean heat transport 42 TW (relative to 0oC) ? Orvik & Skagseth, 2005 Orvik and Sagseth: „... The variations reflect a 25% span between minimum and maximum heat flux in conjunction with a 30% span in volume flux and an about 1°C range in temperature.“

  18. On climatological mass, heat and salt transports through the Barents Sea and Fram Strait from a pan-Arctic coupled ice-ocean model simulation, Maslowski, Marble, Walczowski, Schauer, Clement, Semtner, JGR, 2004 „To compare the flow into the Arctic Ocean via Fram Strait with that through the Barents Sea, mass, heat and salt transports were calculated through Fram Strait and along the northern Barents Sea shelf slope (Table 2, sections B, H and I, Qheat is referenced to –0.1°C … … The amount of heat flowing into the Barents Sea, between Svalbard and Norway, is more than twice that of the amount of heat entering the Arctic Ocean via Fram Strait (i.e., 106TW compared to 47TW).“

  19. ANNUAL MEAN TEMPERATURE AND CROSS-SECTION CURRENTMEASURED BY AN ARRAY OF MOORINGS 2002-03 2002-03 2003-04 2003-04 2004-05 2004-05

  20. Volume, heat and freshwater transports through Fram Strait Bert Rudels, ASOF conference Torshavn: From shelfbreak to shelf break: 9E – 6W Geostrophic calculations, Jacobsen & Jensen (1926) at sloping bottom Deep flow has shallow water to the right Constraints on deep flow (V = – 0.4 Sv, S = – 13.973 x 106 kg/s) Northward transports (~ 6.5 Sv) Southward transports (~ – 9.0 Sv) Net transport (– 2.5 Sv) The mean outflow temperature is chosen as reference temperature The mean inflow salinity is chosen as reference salinity Well?

  21. ?

  22. ANNUAL MEAN TEMPERATURE AND CROSS-SECTION CURRENTMEASURED BY AN ARRAY OF MOORINGS 2002-03 2002-03 DAMOCLES Tomography array 2-6°E 2003-04 2003-04 2004-05 2004-05

  23. Conclusion: If we want to measure oceanic heat transport we have to keep high resolution observations in the straits - if not, not. In DAMOCLES we should not use only new technology but also our brains. F. Nansen, ca.1895

  24. Temperature increase in West Spitsbergen Current 1997-2001 2002-2005 2006 Sal Temp s0

  25. ARRAY OF MOORINGS IN FRAM STRAIT • 1997 - 1999 : 14 moorings • 1999 - 2000 : 11 moorings • 2000 - 2002 : 14 moorings • 2002 - 2005 : 17 moorings DAMOCLES Tomography array 2-6°E 2002-05 ASOF-N array

  26. Østerhus, Turrell, Jónsson, Hansen GRL, 2005 Measured volume, heat, and salt fluxes from the Atlantic to the Arctic Mediterranean The heat delivered to an area by a current depends not only on its initial temperature, but also on the temperature of the water when it leaves the area. Although not very accurately known, all the outflow branches from the Arctic Mediterranean have average temperatures close to 0°C

  27. HOVMÖLLER DIAGRAM OF TEMPERATURE AND CURRENT AT THE DEPTH OF ca 250 m IN 1997-2005 (MONTHLY MEANS) DAMOCLES Tomography array 2-6°E

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