Abstract
We investigate the formation process and pathways of deep water masses in a coupled ice–ocean model of the Arctic and North Atlantic Oceans. The intent is to determine the relative roles of these water masses from the different source regions (Arctic Ocean, Nordic Seas, and Subpolar Atlantic) in the meridional overturning circulation. The model exhibits significant decadal variability in the deep western boundary current and the overturning circulation. We use detailed diagnostics to understand the process of water mass formation in the model and the resulting effects on the North Atlantic overturning circulation. Particular emphasis is given to the multiple sources of North Atlantic Deep Water, the dominant deep water masses of the world ocean. The correct balance of Labrador Sea, Greenland Sea and Norwegian Sea sources is difficult to achieve in climate models, owing to small-scale sinking and convection processes. The global overturning circulation is described as a function of potential temperature and salinity, which more clearly signifies dynamical processes and clarifies resolution problems inherent to the high latitude oceans. We find that fluxes of deep water masses through various passages in the model are higher than observed estimates. Despite the excessive volume flux, the Nordic Seas overflow waters are diluted by strong mixing and enter the Labrador Sea at a lighter density. Through strong subpolar convection, these waters along with other North Atlantic water masses are converted into the densest waters [similar density to Antarctic Bottom Water (AABW)] in the North Atlantic. We describe the diminished role of salinity in the Labrador Sea, where a shortage of buoyant surface water (or excess of high salinity water) leads to overly strong convection. The result is that the Atlantic overturning circulation in the model is very sensitive to the surface heat flux in the Labrador Sea and hence is correlated with the North Atlantic Oscillation. As strong subpolar convection is found in other models, we discuss broader implications.
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References
Bacon S (1998) Decadal variability in the outflow from the Nordic Seas to the deep Atlantic Ocean. Nature 394:871–874
Baringer MO, Larsen JC (2001) Sixteen years of Florida current transport at 27°N. Geophys Res Let 26:3179–3182
Beismann JO, Barnier B (2004) Variability of the meridional overturning circulation of the North Atlantic: sensitivity to overflows of dense water masses. Ocean Dyn 54:92–106
Belkin IM, Levitus S, Antonov J, Malmberg SA (1998) “Great Salinity Anomalies” in the North Atlantic. Prog Oceanogr 41:1–68
Blanke B, Arhan M, Speich S, Pailler K (2002) Diagnosing and picturing the North Atlantic segment of the global conveyor belt by means of an ocean general circulation model. J Phys Oceanogr 32:1430–1451
Blumberg AF, Mellor GL (1987) A description of a three-dimensional coastal ocean circulation model. In: Heaps N (ed) Three-dimensional coastal ocean models, vol. 4 of coastal and estuariane science series. American Geophysical Union, Washington DC, pp 1–16
Boyer TP, Stephens C, Antonov JI, Conkright ME, Locarnini RA, O’Brien TD, Garcia HE (2002) World Ocean Atlas 2001, vol 2: salinity. In: Levitus S (ed) NOAA Atlas NESDIS 50, US Gov Printing Office, Washington DC, 165 pp
Cayan DR (1992) Latent and sensible heat flux anomalies over the northern oceans: the connection to monthly atmospheric circulation. J Clim 5:354–369
Cheng W, Rhines PB (2004) Response of the overturning circulation to high-latitude fresh-water perturbations in the North Atlantic. Clim Dyn 22:359–372. DOI 10.1007/s00382-003-0385-6
Cooper C, Gordon C (2002) North Atlantic decadal variability in the Hadley Centre coupled model. J Clim 15:45–72
Cuny J (2003) Labrador Sea Boundary Currents. Ph.D. thesis, University of Washington
Cuny J, Rhines PB, Kwok R (2004) Davis Strait volume, freshwater and heat transport. Deep Sea Res (submitted)
Curry RG, McCartney MS (2001) Ocean gyre changes associated with the North Atlantic Oscillation. J Phys Oceanogr 31:3374–3400
Delworth TL, Dixon KW (2000) Implications of the recent trend in the Arctic/North Atlantic Oscillation for the North Atlantic thermohaline circulation. J Clim 13:3721–3727
Delworth TL, Greatbatch RJ (2000) Multidecadal thermohaline circulation variability driven by atmospheric surface flux forcing. J Clim 13:1481–1495
Delworth TL, Manabe S, Stouffer RJ (1993) Interdecadal variations of the thermohaline circulation in a coupled ocean-atmosphere model. J Clim 6:1993–2011
Delworth TL, Manabe S, Stouffer RJ (1997) Multidecadal climate variability in the Greenland Sea and surrounding regions: a coupled model simulation. Geophys Res Let 24:257–260
Delworth TL, Stouffer RJ, Dixon KW, Spelman MJ, Knutson TR, Broccoli AJ, Kushner PJ, Wetherald RT (2002) Review of simulations of climate variability and change within the GFDL R30 coupled model. Clim Dyn 19:555–574
Dickson RR, Brown J (1994) The production of North Atlantic Deep Water: sources, rates, and pathways. J Geophys Res 99:12319–12341
Dickson RR, Mencke J, Malmberg SA, Lee AJ (1988) The “Great Salinity Anomaly" in the Northern North Atlantic 1968–1982. Prog Oceanogr 20:103–151
Dickson RR, Yashayaev I, Meincke J, Turrell W, Dye S, Holfort J (2002) Rapid freshening of the deep North Atlantic Ocean over the past four decades. Nature 416:832–837
Dixon KW, Delworth TL, Knutsen TR, Spelman MJ, Stouffer RJ (2003) A comparison of climate change simulations produced by two GFDL coupled climate models. Global Plantary Change 37:81–102
Döscher R, Redler R (1997) The relative importance of northern overflow and subpolar deep convection for the North Atlantic thermohaline circulation. J Phys Oceanogr 27:1894–1902
Döscher R, Böning CW, Herrmann P (1994) Response of circulation and heat transport in the North Atlantic to changes in the thermohaline forcing in northern latitudes: a model study. J Phys Oceanogr 24:2306–2320
Eden C, Jung T (2001) North Atlantic interdecadal variability: oceanic response to the North Atlantic Oscillation (1865–1997). J Clim 14:676–691
Eden C, Willebrand J (2001) Mechanism of interannual to decadal variability of the North Atlantic circulation. J Clim 14:2266–2280
Fahrbach E, Meincke J, Østerhus S, Rohardt G, Schauer U, Tverberg V, Verduin J (2001) Direct measurements of volume transports through Fram Strait. Polar Res 20:217–224
Ganachaud A, Wunsch C (2003) Large-scale ocean heat and freshwater transports during the World Ocean Circulation Experiment. J Clim 16:696–705
Gent PR (2001) Will the North Atlantic Ocean thermohaline circulation weaken during the 21st century? Geophys Res Let 28:1023–1026
Gent PR, McWilliams JC (1990) Isopycnal mixing in ocean circulation models. J Phys Oceanogr 20:150–155
Gerdes R, Köberle C (1995) On the influence of DSOW in a numerical model of the North Atlantic general circulation. J Phys Oceanogr 25:2624–2642
Gulev SK, Barnier B, Knochel H, Molines JM, Cottet M (2003) Water mass transformation in the North Atlantic and its impact on the meridional circulation: Insights from and ocean model forced by NCEP-NCAR reanalysis surface fluxes. J Clim 16:3085–3110
Häkkinen S (1999a) A simulation of thermohaline effects of a great salinity anomaly. J Clim 12:1781–1795
Häkkinen S (1999b) Variability of the simulated meridional heat transport in the North Atlantic for the period 1951–1993. J Geophys Res 104:10991–11007
Häkkinen S (2000) Decadal air–sea interaction in the North Atlantic based on observations and modeling results. J Clim 13:1195–1219
Häkkinen S (2001) Variability in sea surface height: a qualitative measure for the meridional overturning circulation in the North Atlantic. J Geophys Res 106:13837–13848
Häkkinen S (2002a) Freshening of the Labrador Sea surface waters in the 1990s: aAnother great salinity anomaly? Geophys Res Let 29:2232. DOI 10.1029/2002GL015243
Häkkinen S (2002b) Surface salinity variability in the northern North Atlantic during recent decades. J Geophys Res 107:8003. DOI 10.1029/2001JC000812
Häkkinen S, Mellor GL (1992) Modeling the seasonal variability of the coupled Arctic ice–ocean system. J Geophys Res 97:20285–20304
Hallberg R, Rhines P (1996) Buoyancy-driven circulation in an ocean basin with isopycnals intersecting the sloping boundary. J Phys Oceanogr 26:913–940
Hansen B, Turrell WR, Østerhus S (2001) Decreasing overflow from the Nordic Seas into the Atlantic Ocean through the Faroe Bank channel since 1950. Nature 411:927–930
Houghton JT, Ding Y, Griggs DJ, Noguer M, van der Linden PJ, Dai X, Maskell K, Johnson CA (eds) (2001) Climate Change 2001: The Scientific Basis. Contribution of Working Group I to the Third Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge University Press, Cambridge UK, p 881
Hurrell JW (1995) Decadal trends in the North Atlantic Oscillation: regional temperatures and precipitation. Science 269:676–679
Jia Y (2003) Ocean heat transport and its relationship to ocean circulation in the CMIP coupled models. Clim Dyn 20:153–174
Kalnay E, Kanamitsu M, Kistler R, Collins W, Deaven D, Gandina L, Iredell M, Saha S, White G, Woollen J, Zhu Y, Leetmaa A, Reynolds B, , Chelliah M, Ebisuzaki W, Higgins W, Janowiak J, Mo KC, Ropelewski C, Wang J, Jenne R, Joseph D (1996) The NCEP/NCAR 40-Year Reanalysis Project. Bull Am Meteorol Soc 77:437–472
Levitus S (1982) Climatological atlas of the world ocean. NOAA Prof. Pap. 13, US Department of Commerce, Washington DC, 173 pp
Lilly JM (2002) Observations of the Labrador Sea eddy field. PhD Thesis, University of Washington
Marshall J, Johnson H, Goodman J (2001) A study of the interaction of the North Atlantic Oscillation with ocean circulation. J Clim 14:1399–1421
Mauritzen C (1996) Production of dense overflow waters feeding the North Atlantic across the Greenland–Scotland Ridge. Part 2: an inverse model. Deep Sea Res I 43:807–835
Mauritzen C, Häkkinen S (1997) Influence of sea ice on the thermohaline circulation in the Arctic—North Atlantic Ocean. Geophys Res Let 24:3257–3261
Mauritzen C, Häkkinen S (1999) On the relationship between dense water formation and the “Meridional Overturning Cell" in the North Atlantic Ocean. Deep Sea Res I 46:877–894
Mellor GL, Yamada T (1982) Development of a turbulence closure model for geophysical fluid problems. Rev Geophys Space Phys 20:851–875
Mellor GL, Oey LY, Ezer T (1998) Sigma coordinate pressure gradient errors and the seamount problem. J Atmos Oceanic Technol 15:1122–1131
Molinari RL, Fine RA, Wilson WD, Curry RG, Abell J, McCartney MS (1998) The arrival of recently formed Labrador Sea Water in the Deep Western Boundary Current at 26.5°N. Geophys Res Let 25:2249–2252
Rasmusson EM, Mo KC (1996) Large-scale atmospheric moisture cycling as evaluated from NMC global analysis and forecast products. J Clim 9:3276–3297
Schlichtholz P, Houssais MN (1999) An inverse modelling study in Fram Strait. Part I: dynamics and circulation. Deep Sea Res II 46:1083–1135
Smethie WM, Fine RA (2001) Rates of North Atlantic Deep Water formation calculated from chlorofluorocarbon inventories. Deep Sea Res I 48:189–215
Smethie WM, Fine RA, Putzka A, Jones EP (2000) Tracing the flow of North Atlantic Deep Water using chlorofluorocarbons. J Geophys Res 105:14297–14323
Speer K, Tziperman E (1992) Rates of water mass formation in the North Atlantic Ocean. J Phys Oceanogr 22:93–104
Stephens C, Antonov JI, Boyer TP, Conkright ME, Locarnini RA, O’Brien TD, Garcia HE (2002) World Ocean Atlas 2001, vol 1: temperature. In: Levitus S (ed) NOAA Atlas NESDIS 49, US Gov Printing Office, Washington DC, 167 pp
Talley LD (2003) Shallow, intermediate, and deep overturning components of the global heat budget. J Phys Oceanogr 33:530–560
Treguier AM, Theetten S, Chassignet EP, Penduff T, SMith R, Talley L, Beismann JO, Bning C (2005) The North Atlantic subpolar gyre in four high resolution models. J Phys Oceanogr (In press)
Trenberth KE, Caron JM (2001) Estimates of meridional atmosphere and ocean heat transports. J Clim 14:3433–3443
Willebrand J, Barnier B, Böning C, Dieterich C, Killworth PD, Provost CL, Jia Y, Molines JM, New AL (2001) Circulation characteristics in three eddy-permitting models of the North Atlantic. Prog Oceanogr 48:123–161
Wood RA, Keen AB, Mitchell JFB, Gregory JM (1999) Changing spatial structure of the thermohaline circulation in response to atmospheric CO2 forcing in a climate model. Nature 399:572–575
Worthington LV (1970) The Norwegian Sea as a mediterranean basin. Deep Sea Res 17:77–84
Acknowledgments
This work was generously supported by a grant from the Vetlesen Foundation to the School of Oceanography at the University of Washington. We would like to thank L. Thompson, W. Cheng, J. Lilly, and J. Cuny for providing comments and insightful discussions. Constructive comments from two anonymous reviewers and the executive editor helped substantially to improve the manuscript.
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Bailey, D.A., Rhines, P.B. & Häkkinen, S. Formation and pathways of North Atlantic Deep Water in a coupled ice–ocean model of the Arctic–North Atlantic Oceans. Climate Dynamics 25, 497–516 (2005). https://doi.org/10.1007/s00382-005-0050-3
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DOI: https://doi.org/10.1007/s00382-005-0050-3