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Changing Arctic Ocean freshwater pathways



Freshening in the Canada basin of the Arctic Ocean began in the 1990s1,2 and continued3 to at least the end of 2008. By then, the Arctic Ocean might have gained four times as much fresh water as comprised the Great Salinity Anomaly4,5of the 1970s, raising the spectre of slowing global ocean circulation6. Freshening has been attributed to increased sea ice melting1 and contributions from runoff7, but a leading explanation has been a strengthening of the Beaufort High—a characteristic peak in sea level atmospheric pressure2,8—which tends to accelerate an anticyclonic (clockwise) wind pattern causing convergence of fresh surface water. Limited observations have made this explanation difficult to verify, and observations of increasing freshwater content under a weakened Beaufort High suggest that other factors2 must be affecting freshwater content. Here we use observations to show that during a time of record reductions in ice extent from 2005 to 2008, the dominant freshwater content changes were an increase in the Canada basin balanced by a decrease in the Eurasian basin. Observations are drawn from satellite data (sea surface height and ocean-bottom pressure) and in situ data. The freshwater changes were due to a cyclonic (anticlockwise) shift in the ocean pathway of Eurasian runoff forced by strengthening of the west-to-east Northern Hemisphere atmospheric circulation characterized by an increased Arctic Oscillation9 index. Our results confirm that runoff is an important influence on the Arctic Ocean and establish that the spatial and temporal manifestations of the runoff pathways are modulated by the Arctic Oscillation, rather than the strength of the wind-driven Beaufort Gyre circulation.

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Figure 1: 2008 Arctic Ocean salinity anomaly and geostrophic velocity at 50–60 m depth.
Figure 2: Rates of change between 2005 and 2008 of DOT, SPA and freshwater content.
Figure 3: 2006–2008 anomalies relative to 2004–2005 averages of SLP, DOT and SPA.
Figure 4: Schematic views of the idealized Arctic Ocean circulation patterns under low and high AO anomalies.

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  1. McPhee, M. G., Stanton, T. P., Morison, J. H. & Martinson, D. G. Freshening of the upper ocean in the Arctic: is perennial sea ice disappearing? Geophys. Res. Lett. 25, 1729–1732 (1998)

    Article  ADS  CAS  Google Scholar 

  2. Proshutinsky, A. et al. Beaufort Gyre freshwater reservoir: state and variability from observations. J. Geophys. Res. 114, C00A10, (2009)

  3. Rabe, B. et al. An assessment of Arctic Ocean freshwater content changes from the 1990s to the 2006–2008 period. Deep Sea Res. I 58, 173–185 (2011)

    Article  Google Scholar 

  4. McPhee, M. G., Proshutinsky, A., Morison, J., Steele, M. & Alkire, M. Rapid change in freshwater content of the Arctic Ocean. Geophys. Res. Lett. 36, L10602, (2009)

  5. Dickson, R. R., Meincke, J., Malmberg, S. A. & Lee, A. J. The ‘Great Salinity Anomaly’ in the northern North Atlantic 1968–1982. Prog. Oceanogr. 20, 103–151 (1988)

    Article  ADS  Google Scholar 

  6. Proshutinsky, A. Y. & Johnson, M. A. Two circulation regimes of the wind-driven Arctic Ocean. J. Geophys. Res. 102, 12493–12514 (1997)

    Article  ADS  Google Scholar 

  7. Macdonald, R. W., Carmack, E. C., McLaughlin, F. A., Falkner, K. K. & Swift, J. H. Connections among ice, runoff and atmospheric forcing in the Beaufort Gyre. Geophys. Res. Lett. 26, 2223–2226 (1999)

    Article  ADS  CAS  Google Scholar 

  8. Proshutinsky, A., Bourke, R. H. & McLaughlin, F. A. The role of the Beaufort Gyre in Arctic climate variability: seasonal to decadal climate scales. Geophys. Res. Lett. 29, 2100, (2002)

  9. Thompson, D. W. J. & Wallace, J. M. The Arctic Oscillation signature in the wintertime geopotential height and temperature fields. Geophys. Res. Lett. 25, 1297–1300 (1998)

    Article  ADS  Google Scholar 

  10. Morison, J., Steele, M. & Andersen, R. Hydrography of the upper Arctic Ocean measured from the nuclear submarine USS Pargo. Deep Sea Res. I 45, 15–38 (1998)

    Article  Google Scholar 

  11. Carmack, E. C. et al. Changes in temperature and tracer distributions within the Arctic Ocean: results from the 1994 Arctic Ocean Section. Deep Sea Res. II 44, 1487–1502 (1997)

    Article  ADS  CAS  Google Scholar 

  12. Environmental Working Group (EWG). Joint U.S.-Russian Atlas of the Arctic Ocean, Oceanography Atlas for the Winter Period (National Ocean Data Center (NODC), 1997)

  13. Morison, J., Aagaard, K. & Steele, M. Recent environmental changes in the Arctic. Arctic 53, 359–371 (2000)

    Article  Google Scholar 

  14. Lique, C. et al. Evolution of the Arctic Ocean Salinity, 2007–08: contrast between the Canadian and the Eurasian Basins. J. Clim. 24, 1705–1717 (2011)

    Article  ADS  Google Scholar 

  15. Kwok, R. & Morison, J. Dynamic topography of the ice-covered Arctic Ocean from ICESat. Geophys. Res. Lett. 38 L02501 (2011)

    Article  ADS  Google Scholar 

  16. Alkire, M. B. et al. Sensor-based profiles of the NO parameter in the central Arctic and southern Canada Basin: new insights regarding the cold halocline. Deep Sea Res. I 57, 1432–1443 (2010)

    Article  CAS  Google Scholar 

  17. Yamamoto-Kawai, M., McLaughlin, F. A., Carmack, E. C., Nishino, S. & Shimada, K. Freshwater budget of the Canada Basin, Arctic Ocean, from salinity, δ18O, and nutrients. J. Geophys. Res. 113 C01007 (2008)

    Article  ADS  Google Scholar 

  18. Chambers, D. P. Observing seasonal steric sea level variations with GRACE and satellite altimetry. J. Geophys. Res. 111 C03010 (2006)

    Article  ADS  Google Scholar 

  19. Willis, J. K., Chambers, D. P. & Nerem, R. S. Assessing the globally averaged sea level budget on seasonal to interannual timescales. J. Geophys. Res. 113 C06015 (2008)

    Article  ADS  Google Scholar 

  20. Vinogradova, N., Ponte, R. M. & Stammer, D. Relation between sea level and bottom pressure and the vertical dependence of oceanic variability. Geophys. Res. Lett. 113, L03608, (2007)

  21. Bingham, R. J. & Hughes, C. W. The relationship between sea-level and bottom pressure variability in an eddy permitting ocean model. Geophys. Res. Lett. 35 L03602 (2008)

    Article  ADS  Google Scholar 

  22. Morison, J., Wahr, J., Kwok, R. & Peralta-Ferriz, C. Recent trends in Arctic Ocean mass distribution revealed by GRACE. Geophys. Res. Lett. 34, L07602, (2007)

  23. Steele, M. & Ermold, W. Steric sea level change in the Northern Seas. J. Clim. 20, 403–417 (2007)

    Article  ADS  Google Scholar 

  24. Kwok, R. et al. Thinning and volume loss of the Arctic Ocean sea ice cover: 2003–2008. J. Geophys. Res. 114 C07005 (2009)

    Article  ADS  Google Scholar 

  25. Serreze, M. C. et al. The large-scale freshwater cycle of the Arctic. J. Geophys. Res. 111, C11010, (2006)

  26. Ekwurzel, B., Schlosser, P., Mortlock, R. A., Fairbanks, R. G. & Swift, J. H. River runoff, sea ice meltwater, and Pacific water distribution and mean residence times in the Arctic Ocean. J. Geophys. Res. 106, 9075–9092 (2001)

    Article  ADS  CAS  Google Scholar 

  27. Steele, M. & Boyd, T. Retreat of the cold halocline layer in the Arctic Ocean. J. Geophys. Res. 103, 10419–10435 (1998)

    Article  ADS  CAS  Google Scholar 

  28. Shindell, D. T., Miller, R. L., Schmidt, G. A. & Pandolfo, L. Simulation of recent northern winter climate trends by greenhouse-gas forcing. Nature 399, 452–455 (1999)

    Article  ADS  CAS  Google Scholar 

  29. Koldunov, N. V., Stammer, D. & Marotzke, J. Present-day Arctic sea ice variability in the coupled ECHAM5/MPI-OM model. J. Clim. 23, 2520–2543 (2010)

    Article  ADS  Google Scholar 

  30. Walsh, J. E., Chapman, W. L., Romanovsky, V., Christensen, J. H. & Stendel, M. Global Climate Model performance over Alaska and Greenland. J. Clim. 21, 6156–6174 (2008)

    Article  ADS  Google Scholar 

  31. Chambers, D. P. Evaluation of new GRACE time-variable gravity data over the ocean. Geophys. Res. Lett. 33, L17603 (2006)

    Article  ADS  Google Scholar 

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This work was supported chiefly by NSF grants OPP 0352754, ARC-0634226, ARC-0856330 and NASA grant NNX08AH62G. R.K. was supported at the Jet Propulsion Laboratory, California Institute of Technology, under contract with NASA. GRACE ocean data were processed by D. P. Chambers, supported by the NASA MEASURES Program. We thank the NASA ICESat and GRACE programmes, K. Falkner, R. Collier, M. McPhee, W. Ermold, L. de Steur, A. Proshutinsky and the Beaufort Gyre Exploration Project, J. Toole and R. Krishfield and the Ice Tethered Profiler project at WHOI, and W. Smethie of the Switchyard project for the observations that made this work possible.

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The main idea was developed by J.M. and R.K. J.M. wrote most of the text and with R.A. and C.P.-F. drew most of the figures. R.K. developed the DOT records. The SLP and OBP anomaly plots were originally developed by C.P.-F. The 2008 hydrography observations were made by J.M., M.A., R.A. and M.S. The AO spatial pattern data, figures and insight were provided by I.R. The hydrographic data processing was done by R.A. and the chemistry analysis was done by M.A. Switchyard data and freshwater insight was provided by M.S. All authors discussed the results and commented on the manuscript.

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Correspondence to James Morison.

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Morison, J., Kwok, R., Peralta-Ferriz, C. et al. Changing Arctic Ocean freshwater pathways. Nature 481, 66–70 (2012).

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