Abstract
Deep convection in the Labrador Sea is confined within a small region in the southwest part of the basin. The strength of deep convection in this region is related to the local atmospheric and ocean characteristics, which favor processes of deep convection preconditioning and intense air-sea exchange during the winter season. In this study, we explored the effect of eddy-induced flux transport on the stratification of the Labrador Sea and the properties of deep convection. Simulations from an eddy-resolving ocean model are presented for the Labrador Sea. The general circulation was well simulated by the model, including the seasonal cycle of the deep Labrador Current. The simulated distribution of the surface eddy kinetic energy was also close to that derived from Topex-Poseidon satellite altimeter data, but with smaller magnitude. The energy transfer diagnostics indicated that Irminger rings are generated by both baroclinic and barotropic processes; however, when they propagate into the interior basin, the barotropic process also disperses them by converting the eddy energy to the mean flow. In contrast to eddy-permitting simulations, deep convection in the Labrador Sea was better represented in the eddy-resolving model regarding their lateral position. Further analysis indicated that the improvement might be due to the lateral eddy flux associated with the resolved Irminger rings in the eddy-resolving model, which contributes to a realistic position of the isopycnal dome in the Labrador Sea and correspondingly a realistic site of deep convection.
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Antonov, J. I., R. A. Locarnini, T. P. Boyer, A. V. Mishonov, and H. E. Garcia, 2006: World Ocean Atlas 2005, Volume 2: Salinity. S. Levitus, Ed. NOAA Atlas NESDIS 62, U. S. Government Printing Office, Washington, D. C., 182 pp.
Blanke, B., and P. Delecluse, 1993: Low frequency variability of the tropical Atlantic Ocean simulated by a general circulation model with mixed layer physics. J. Phys. Oceanogr., 23, 1363–1388.
Blayo, E., and L. Debreu, 1999: Adaptive mesh refinement for finite-difference ocean models: First experiments. J. Phys. Oceanogr., 29, 1239–1250.
Bracco, A., and J. Pedlosky, 2003: Vortex generation by topography in locally unstable baroclinic flow. J. Phys. Oceanogr., 33, 207–219.
Bracco, A., J. Pedlosky, and R. Pickart, 2008: Eddy formation near the West coast of Greenland. J. Phys. Oceanogr., 38, 1992–2002.
Brankart, J.-M., and P. Brasseur, 1998: The general circulation in the Mediterranean Sea: A climatological approach. J. Mar. Syst., 18, 41–70.
Chanut, J., B. Barnier, W. Large, L. Debreu, T. Penduff, J. M. Molines and P. Mathiot, 2008: Mesoscale eddies in the Labrador Sea and their contribution to convection and restratification J. Phys. Oceanogr., 38, 1617–1643.
Clarke, R. A., and J.-C. Gascard, 1983: The formation of Labrador Sea Water. Part I: Large-scale processes. J. Phys. Oceanogr., 13, 1764–1778.
Cooke, M. A., E. Demirov, and J. Zhu, 2014: A model study of the relationship between sea-ice variability and surface and intermediate water mass properties in the Labrador Sea. Atmosphere-Ocean, 52(2), 142–154, doi: 10.1080/07055900.2013.877417.
Debreu, L., E. Blayo, and B. Barnier, 2005: A general adaptive multi-resolution approach to ocean modelling: Experiments in a primitive equation model of the North Atlantic. Adaptive Mesh Refinement: Theory and Applications. Vol. 41, Lecture Notes in Computational Science and Engineering, T. Plewa et al., Eds., Springer, 303–314.
Demirov, E. K., and N. Pinardi, 2007: On the relationship between the water mass pathways and eddy variability in the western Mediterranean Sea. J. Geophys. Res., 112, C02024, doi: 10.1029/2005JC003174.
Dengler, M., J. Fischer, F. A. Schott, and R. Zantopp, 2006: Deep Labrador Current and its variability in 1996–2005. Geophys. Res. Lett., 33, L21S06, doi: 10.1029/2006GL026702.
Ducet, N., P. Y. Le Traon, and G. Reverdin, 2000: Global high-resolution mapping of ocean circulation from TOPEX/Poseidon and ERS-1 and -2. J. Geophys. Res., 105 (C8), 19 477–19 498.
Eden, C., and C. Böning, 2002: Sources of eddy kinetic energy in the Labrador Sea. J. Phys. Oceanogr., 32, 3346–3363.
Fichefet, T., and M. A. M. Maqueda, 1997: Sensitivity of a global sea ice model to the treatment of ice thermodynamics and dynamics. J. Geophys. Res., 102, 12 609–12 646.
Fratantoni, D. M., 2001: North Atlantic surface circulation during the 1990’s observed with satellite-tracked drifters. J. Geophys. Res., 106, 22 067–22 093.
Gao, Y. Q., and L. Yu, 2008: Subpolar gyre index and the North Atlantic meridional overturning circulation in a coupled climate model. Atmospheric and Oceanic Science Letters, 1, 29–32.
Gaspar, P., Y. Grégoris, and J.-M. Lefevre, 1990: A simple eddy kinetic energy model for simulations of the oceanic vertical mixing Tests at station papa and long-term upper ocean study site. J. Geophys. Res., 95, 16 179–16 193.
Gent, P. R., and J. C. McWilliams, 1990: Isopycnal mixing in ocean circulation models. J. Phys. Oceanogr., 20, 150–155.
Hátún, H., C. C. Eriksen, and P. B. Rhines, 2007: Buoyant eddies entering the Labrador Sea observed with gliders and altimetry. J. Phys. Oceanogr., 37, 2838–2854.
Kalnay, E., and Coauthors, 1996: The NCEP/NCAR 40-Year Reanalysis Project. Bull. Amer. Meteor. Soc., 77, 437–472.
Käse, R. H., A. Biastoch, and D. B. Stammer, 2001: On the middepth circulation in the Labrador and Irminger seas. Geophys. Res. Lett., 28, 3433–3436.
Katsman, C. A., M. A. Spall, and R. S. Pickart, 2004: Boundary current eddies and their role in the restratification of the Labrador Sea. J. Phys. Oceanogr., 34, 1967–1983.
Lavender, K. L., R. E. Davis, and W. B. Owens, 2000: Mid-depth recirculation observed in the interior Labrador and Irminger seas by direct velocity measurements. Nature, 407, 66–69.
Lazier, J. R. N., and D. G. Wright, 1993: Annual velocity variations in the Labrador Current. J. Phys. Oceanogr., 23, 659–678.
Lilly, J. M., P. B. Rhines, F. Schott, K. Lavender, J. Lazier, U. Send, and E. D’Asaro, 2003: Observations of the Labrador Sea eddy field. Progress in Oceanography, 59, 75–176.
Locarnini, R. A., A. V. Mishonov, J. I. Antonov, T. P. Boyer, and H. E. Garcia, 2006: Temperature. Vol. 1, World Ocean Atlas 2005, S. Levitus, Ed., NOAA Atlas NESDIS 61, U. S. Government Printing Office, Washington, D. C., 182 pp.
Madec, G., 2008: “NEMO reference manual, ocean dynamics component: NEMO-OPA. Preliminary version”. Note du Pole de modélisation, Institut Pierre-Simon Laplace (IPSL), France, No 27.
Marshall, J., and F. Schott, 1999: Open-ocean convection: Observations, theory, and models. Rev. Geophys., 37, 1–64.
Molines, J. M., B. Barnier, T. Penduff, L. Brodeau, A. Treguier, S. Theetten, and G. Madec, 2007: Definition of the interannual experiment ORCA025-G70, 1958–2004. LEGI Report, LEGI-DRA-2-11-2006, 34 pp.
Pickart, R. S., D. J. Torres, and R. A. Clarke, 2002: Hydrography of the Labrador Sea during active convection. J. Phys. Oceanogr., 32, 428–457.
Prater, M. D., 2002: Eddies in the Labrador Sea as observed by profiling RAFOS floats and remote sensing. J. Phys. Oceanogr., 32, 411–427.
Rykova, T., F. Straneo, J. M. Lilly, and I. Yashayaev, 2009: Irminger current anticyclones in the Labrador Sea observed in the hydrographic record, 1990–2004. J. Mar. Res., 67, 361–384.
Solomon, S., and Coauthors, 2007: Climate Change 2007: The Physical Science Basis. Cambridge University Press, 996 pp.
Stammer, D., C. Böning, and C. Dieterich, 2001: The role of vari able wind forcing in generating eddy energy in the North Atlantic. Progress in Oceanography, 48, 289–312.
Straneo, F., 2006: Heat and freshwater transport through the central Labrador Sea. J. Phys. Oceanogr., 36, 606–628.
Straneo, F., R. S. Pickart, and K. Lavender, 2003: Spreading of Labrador Sea Water: An advective-diffusive study based on Lagrangian data. Deep-Sea Res. I, 50, 701–719.
Thompson, K. R., D. G. Wright, Y. Lu, and E. Demirov, 2006: A simple method for reducing seasonal bias and drift in eddy resolving ocean models. Ocean Modelling, 13, 109–125.
Tréguier, A.-M., S. Theetten, E. Chassignet, T. Penduff, R. Smith, L. Talley, J. O. Beismann, and C. Böning, 2005: The North Atlantic subpolar gyre in four high-resolution models. J. Phys. Oceanogr., 35, 757–774.
U. S. Department of Commerce, National Oceanic and Atmospheric Administration, National Geophysical Data Center, 2006: 2-minute Gridded Global Relief Data (ETOPO2v2). [Available online at http://www.ngdc.noaa.gov/mgg/fliers/01mgg04.html].
White, M., and K. Heywood, 1995: Seasonal and interannual changes in the North Atlantic subpolar gyre from Geosat and TOPEX/POSEIDON altimetry. J. Geophys. Res., 100(C12), 24 931–24 941.
Willebrand, J., and Coauthors, 2001: Circulation characteristics in three eddy-permitting models of the North Atlantic. Progress in Oceanography, 48, 123–161.
Wright, D. G., 1981: Baroclinic instability in Drake Passage. J. Phys. Oceanogr., 11, 231–246.
Zhu, J. S., E. Demirov, F. Dupont, and D. Wright, 2010: Eddypermitting simulations of the Sub-polar North Atlantic: Impact of the model bias on water mass properties and circulation. Ocean Dyn., 60, 1177–1192, doi: 10.1007/s10236-010-0320-4.
Zhu, J., and E. Demirov, 2011: On the mechanism of interannual variability of the Irminger Water in the Labrador Sea. J. Geophys. Res., 116, C03014, doi:10.1029/2009JC005677.
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Zhu, J., Demirov, E., Zhang, Y. et al. Model simulations of mesoscale eddies and deep convection in the Labrador Sea. Adv. Atmos. Sci. 31, 743–754 (2014). https://doi.org/10.1007/s00376-013-3107-y
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DOI: https://doi.org/10.1007/s00376-013-3107-y