• Alexander, M. A., I. Bladé, M. Newman, J. R. Lanzante, N.-C. Lau, and J. D. Scott, 2002: The atmospheric bridge: The influence of ENSO teleconnections on air–sea interaction over the global oceans. J. Climate, 15, 22052231, https://doi.org/10.1175/1520-0442(2002)015<2205:TABTIO>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Backeberg, B. C., J. A. Johannessen, L. Bertino, and C. J. Reason, 2008: The greater Agulhas Current system: An integrated study of its mesoscale variability. J. Oper. Oceanogr., 1, 2944, https://doi.org/10.1080/1755876X.2008.11020093.

    • Search Google Scholar
    • Export Citation
  • Beal, L. M., and Coauthors, 2011: On the role of the Agulhas system in ocean circulation and climate. Nature, 472, 429436, https://doi.org/10.1038/nature09983.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Beal, L. M., S. Elipot, A. Houk, and G. M. Leber, 2015: Capturing the transport variability of a western boundary jet: Results from the Agulhas Current Time-Series Experiment (ACT). J. Phys. Oceanogr., 45, 13021324, https://doi.org/10.1175/JPO-D-14-0119.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Behera, S. K., and T. Yamagata, 2001: Subtropical SST dipole events in the southern Indian Ocean. Geophys. Res. Lett., 28, 327330, https://doi.org/10.1029/2000GL011451.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Biastoch, A., and C. W. Böning, 2013: Anthropogenic impact on Agulhas leakage. Geophys. Res. Lett., 40, 11381143, https://doi.org/10.1002/grl.50243.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Biastoch, A., C. W. Böning, and J. R. E. Lutjeharms, 2008a: Agulhas leakage dynamics affects decadal variability in Atlantic overturning circulation. Nature, 456, 489492, https://doi.org/10.1038/nature07426.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Biastoch, A., J. R. E. Lutjeharms, C. W. Böning, and M. Scheinert, 2008b: Mesoscale perturbations control inter-ocean exchange south of Africa. Geophys. Res. Lett., 35, L20602, https://doi.org/10.1029/2008GL035132.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Biastoch, A., C. W. Böning, F. U. Schwarzkopf, and J. R. E. Lutjeharms, 2009: Increase in Agulhas leakage due to poleward shift of Southern Hemisphere westerlies. Nature, 462, 495498, https://doi.org/10.1038/nature08519.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Biastoch, A., J. V. Durgadoo, A. K. Morrison, E. van Sebille, W. Weijer, and S. M. Griffies, 2015: Atlantic multi-decadal oscillation covaries with Agulhas leakage. Nat. Commun., 6, 10082, https://doi.org/10.1038/ncomms10082.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Blamey, R. C., and C. J. C. Reason, 2009: Numerical simulation of a mesoscale convective system over the east coast of South Africa. Tellus, 61A, 1734, https://doi.org/10.1111/j.1600-0870.2008.00366.x.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Boebel, O., J. Lutjeharms, C. Schmid, W. Zenk, T. Rossby, and C. Barron, 2003: The Cape Cauldron: A regime of turbulent inter-ocean exchange. Deep-Sea Res. II, 50, 5786, https://doi.org/10.1016/S0967-0645(02)00379-X.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Byrne, D., M. Münnich, I. Frenger, and N. Gruber, 2016: Mesoscale atmosphere ocean coupling enhances the transfer of wind energy into the ocean. Nat. Commun., 7, ncomms11867, https://doi.org/10.1038/ncomms11867.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Castellanos, P., E. J. D. Campos, I. Giddy, and W. Santis, 2016: Inter-comparison studies between high-resolution HYCOM simulation and observational data: The South Atlantic and the Agulhas leakage system. J. Mar. Syst., 159, 7688, https://doi.org/10.1016/j.jmarsys.2016.02.010.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Chelton, D. B., and M. G. Schlax, 2003: The accuracies of smoothed sea surface height fields constructed from tandem satellite altimeter datasets. J. Atmos. Oceanic Technol., 20, 12761302, https://doi.org/10.1175/1520-0426(2003)020<1276:TAOSSS>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Cheng, Y., D. Putrasahan, L. Beal, and B. Kirtman, 2016: Quantifying Agulhas leakage in a high-resolution climate model. J. Climate, 29, 68816892, https://doi.org/10.1175/JCLI-D-15-0568.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • de Ruijter, W. P. M., A. Biastoch, S. S. Drijfhout, J. R. E. Lutjeharms, R. P. Matano, T. Pichevin, P. J. Van Leeuwen, and W. Weijer, 1999: Indian-Atlantic interocean exchange: Dynamics, estimation and impact. J. Geophys. Res., 104, 20 88520 910, https://doi.org/10.1029/1998JC900099.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Dieppois, B., M. Rouault, and M. New, 2015: The impact of ENSO on Southern African rainfall in CMIP5 ocean atmosphere coupled climate models. Climate Dyn., 45, 24252442, https://doi.org/10.1007/s00382-015-2480-x.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Doglioli, A. M., M. Veneziani, B. Blanke, S. Speich, and A. Griffa, 2006: A Lagrangian analysis of the Indian-Atlantic interocean exchange in a regional model. Geophys. Res. Lett., 33, L14611, https://doi.org/10.1029/2006GL026498.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Donners, J., and S. S. Drijfhout, 2004: The Lagrangian view of South Atlantic interocean exchange in a global ocean model compared with inverse model results. J. Phys. Oceanogr., 34, 10191035, https://doi.org/10.1175/1520-0485(2004)034<1019:TLVOSA>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Durgadoo, J. V., B. R. Loveday, C. J. C. Reason, P. Penven, and A. Biastoch, 2013: Agulhas leakage predominantly responds to the Southern Hemisphere westerlies. J. Phys. Oceanogr., 43, 21132131, https://doi.org/10.1175/JPO-D-13-047.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Elipot, S., and L. M. Beal, 2015: Characteristics, energetics, and origins of Agulhas Current meanders and their limited influence on ring shedding. J. Phys. Oceanogr., 45, 22942314, https://doi.org/10.1175/JPO-D-14-0254.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Fauchereau, N., B. Pohl, C. J. C. Reason, M. Rouault, and Y. Richard, 2009: Recurrent daily OLR patterns in the Southern Africa/Southwest Indian Ocean region, implications for South African rainfall and teleconnections. Climate Dyn., 32, 575591, https://doi.org/10.1007/s00382-008-0426-2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Gelaro, R., and Coauthors, 2017: The Modern-Era Retrospective Analysis for Research and Applications, Version 2 (MERRA-2). J. Climate, 30, 54195454, https://doi.org/10.1175/JCLI-D-16-0758.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Gent, P. R., S. G. Yeager, R. B. Neale, S. Levis, and D. A. Bailey, 2010: Improvements in a half degree atmosphere/land version of the CCSM. Climate Dyn., 34, 819833, https://doi.org/10.1007/s00382-009-0614-8.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Gordon, A. L., 1986: Interocean exchange of thermocline water. J. Geophys. Res., 91, 50375046, https://doi.org/10.1029/JC091iC04p05037.

  • Gordon, A. L., R. F. Weiss, W. M. Smethie, and M. J. Warner, 1992: Thermocline and intermediate water communication between the South Atlantic and Indian Oceans. J. Geophys. Res., 97, 72237240, https://doi.org/10.1029/92JC00485.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Hoell, A., C. Funk, T. Magadzire, J. Zinke, and G. Husak, 2015: El Niño–Southern Oscillation diversity and Southern Africa teleconnections during austral summer. Climate Dyn., 45, 15831599, https://doi.org/10.1007/s00382-014-2414-z.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Holton, L., J. Deshayes, B. C. Backeberg, B. R. Loveday, J. C. Hermes, and C. J. C. Reason, 2017: Spatio-temporal characteristics of Agulhas leakage: A model inter-comparison study. Climate Dyn., 48, 21072121, https://doi.org/10.1007/s00382-016-3193-5.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Jury, M. R., 2015: Passive suppression of South African rainfall by the Agulhas Current. Earth Interact., 19, https://doi.org/10.1175/EI-D-15-0017.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Jury, M. R., H. R. Valentine, and J. R. E. Lutjeharms, 1993: Influence of the Agulhas Current on summer rainfall along the southeast coast of South Africa. J. Appl. Meteor., 32, 12821287, https://doi.org/10.1175/1520-0450(1993)032<1282:IOTACO>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Kirtman, B. P., and Coauthors, 2012: Impact of ocean model resolution on CCSM climate simulations. Climate Dyn., 39, 13031328, https://doi.org/10.1007/s00382-012-1500-3.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Kuwano-Yoshida, A., S. Minobe, and S. P. Xie, 2010: Precipitation response to the Gulf Stream in an atmospheric GCM. J. Climate, 23, 36763698, https://doi.org/10.1175/2010JCLI3261.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Le Bars, D., H. A. Dijkstra, and W. P. M. de Ruijter, 2013: Impact of the Indonesian Throughflow on Agulhas leakage. Ocean Sci., 9, 773785, https://doi.org/10.5194/os-9-773-2013.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Le Bars, D., J. V. Durgadoo, and H. A. Dijkstra, 2014: An observed 20 yr time-series of Agulhas leakage. Ocean Sci., 10, 601609, https://doi.org/10.5194/os-10-601-2014.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Li, Z., J. C. McWilliams, K. Ide, and J. D. Farrara, 2015: Coastal ocean data assimilation using a multi-scale three-dimensional variational scheme. Ocean Dyn., 65, 10011015, https://doi.org/10.1007/s10236-015-0850-x.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Lilly, J. M., 2017: jLab: A data analysis package for Matlab, v.1.6.5. Accessed February 2017, http://www.jmlilly.net/jmlsoft.html.

  • Lindesay, J. A., 1988: South African rainfall, the Southern Oscillation and a Southern Hemisphere semi-annual cycle. Int. J. Climatol., 8, 1730, https://doi.org/10.1002/joc.3370080103.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Loveday, B. R., J. V. Durgadoo, C. J. C. Reason, A. Biastoch, and P. Penven, 2014: Decoupling of the Agulhas leakage from the Agulhas Current. J. Phys. Oceanogr., 44, 17761797, https://doi.org/10.1175/JPO-D-13-093.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Loveday, B. R., P. Penven, and C. J. C. Reason, 2015: Southern Annular Mode and westerly-wind-driven changes in Indian-Atlantic exchange mechanisms. Geophys. Res. Lett., 42, 49124921, https://doi.org/10.1002/2015GL064256.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Marshall, G. J., 2003: Trends in the southern annular mode from observations and reanalyses. J. Climate, 16, 41344143, https://doi.org/10.1175/1520-0442(2003)016<4134:TITSAM>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Mason, S. J., 1995: Sea-surface temperature–South African rainfall associations, 1910-1989. Int. J. Climatol., 15, 119135, https://doi.org/10.1002/joc.3370150202.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • McClean, J. L., and Coauthors, 2011: A prototype two-decade fully-coupled fine-resolution CCSM simulation. Ocean Modell., 39, 1030, https://doi.org/10.1016/j.ocemod.2011.02.011.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Mey, R. D., N. D. Walker, and M. R. Jury, 1990: Surface heat fluxes and marine boundary layer modification in the Agulhas Retroflection region. J. Geophys. Res., 95, 15 99716 015, https://doi.org/10.1029/JC095iC09p15997.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Minobe, S., A. Kuwano-Yoshida, N. Komori, S.-P. Xie, and R. J. Small, 2008: Influence of the Gulf Stream on the troposphere. Nature, 452, 206209, https://doi.org/10.1038/nature06690.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Nkwinkwa Njouodo, A. S. N., S. Koseki, N. Keenlyside, and M. Rouault, 2018: Atmospheric signature of the Agulhas Current. Geophys. Res. Lett., 45, 51855193, https://doi.org/10.1029/2018GL077042.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Ou, H. W., and W. De Ruijter, 1986: Separation of an inertial boundary current from a curved coastline. J. Phys. Oceanogr., 16, 280289, https://doi.org/10.1175/1520-0485(1986)016<0280:SOAIBC>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Paris, C. B., J. Helgers, E. van Sebille, and A. Srinivasan, 2013: Connectivity Modeling System: A probabilistic modeling tool for the multi-scale tracking of biotic and abiotic variability in the ocean. Environ. Modell. Software, 42, 4754, https://doi.org/10.1016/j.envsoft.2012.12.006.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Peeters, F. J. C., R. Acheson, G.-J. A. Brummer, W. P. M. de Ruijter, R. R. Schneider, G. M. Ganssen, E. Ufkes, and D. Kroon, 2004: Vigorous exchange between the Indian and Atlantic Oceans at the end of the past five glacial periods. Nature, 430, 661665, https://doi.org/10.1038/nature02785.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Philippon, N., M. Rouault, Y. Richard, and A. Favre, 2012: The influence of ENSO on winter rainfall in South Africa. Int. J. Climatol., 32, 23332347, https://doi.org/10.1002/joc.3403.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Putrasahan, D., B. P. Kirtman, and L. M. Beal, 2016: Modulation of SST interannual variability in the Agulhas leakage region associated with ENSO. J. Climate, 29, 70897102, https://doi.org/10.1175/JCLI-D-15-0172.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Reason, C. J. C., 2001a: Evidence for the influence of the Agulhas Current on regional atmospheric circulation patterns. J. Climate, 14, 27692778, https://doi.org/10.1175/1520-0442(2001)014<2769:EFTIOT>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Reason, C. J. C., 2001b: Subtropical Indian Ocean SST dipole events and southern African rainfall. Geophys. Res. Lett., 28, 22252227, https://doi.org/10.1029/2000GL012735.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Reason, C. J. C., and H. Mulenga, 1999: Relationships between South African rainfall and SST anomalies in the Southwest Indian Ocean. Int. J. Climatol., 19, 16511673, https://doi.org/10.1002/(SICI)1097-0088(199912)19:15<1651::AID-JOC439>3.0.CO;2-U.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Reason, C. J. C., and D. Jagadheesha, 2005: Relationships between South Atlantic SST variability and atmospheric circulation over the South African region during austral winter. J. Climate, 18, 33393355, https://doi.org/10.1175/JCLI3474.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Reason, C. J. C., and M. Rouault, 2005: Links between the Antarctic Oscillation and winter rainfall over western South Africa. Geophys. Res. Lett., 32, L07705, https://doi.org/10.1029/2005GL022419.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Reason, C. J. C., M. Rouault, J. L. Melice, and D. Jagadheesha, 2002: Interannual winter rainfall variability in SW South Africa and large scale ocean–atmosphere interactions. Meteor. Atmos. Phys., 80, 1929, https://doi.org/10.1007/s007030200011.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Renault, L., J. C. McWilliams, and S. Masson, 2017a: Satellite observations of imprint of oceanic current on wind stress by air-sea coupling. Sci. Rep., 7, 17747, https://doi.org/10.1038/s41598-017-17939-1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Renault, L., J. C. McWilliams, and P. Penven, 2017b: Modulation of the Agulhas Current retroflection and leakage by oceanic current interaction with the atmosphere in coupled simulations. J. Phys. Oceanogr., 47, 20772100, https://doi.org/10.1175/JPO-D-16-0168.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Rhines, P. B., and W. R. Holland, 1979: A theoretical discussion of eddy-driven mean flows. Dyn. Atmos. Oceans, 3, 289325, https://doi.org/10.1016/0377-0265(79)90015-0.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Richardson, P. L., 2007: Agulhas leakage into the Atlantic estimated with subsurface floats and surface drifters. Deep-Sea Res. I, 54, 13611389, https://doi.org/10.1016/j.dsr.2007.04.010.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Rouault, M., S. A. White, C. J. C. Reason, J. R. E. Lutjeharms, and I. Jobard, 2002: Ocean–atmosphere interaction in the Agulhas Current region and a South African extreme weather event. Wea. Forecasting, 17, 655669, https://doi.org/10.1175/1520-0434(2002)017<0655:OAIITA>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Rouault, M., P. Penven, and B. Pohl, 2009: Warming in the Agulhas Current system since the 1980’s. Geophys. Res. Lett., 36, L12602, https://doi.org/10.1029/2009GL037987.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Rouault, M., B. Pohl, and P. Penven, 2010: Coastal oceanic climate change and variability from 1982 to 2009 around South Africa. Afr. J. Mar. Sci., 32, 237246, https://doi.org/10.2989/1814232X.2010.501563.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Singleton, A. T., and C. J. C. Reason, 2006: Numerical simulations of a severe rainfall event over the Eastern Cape coast of South Africa: Sensitivity to sea surface temperature and topography. Tellus, 58A, 335367, https://doi.org/10.1111/j.1600-0870.2006.00180.x.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Singleton, A. T., and C. J. C. Reason, 2007: Variability in the characteristics of cut-off low pressure systems over subtropical southern Africa. Int. J. Climatol., 27, 295310, https://doi.org/10.1002/joc.1399.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Siqueira, L., and B. P. Kirtman, 2016: Atlantic near-term climate variability and the role of a resolved Gulf Stream. Geophys. Res. Lett., 43, 39643972, https://doi.org/10.1002/2016GL068694.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Small, R. J., and Coauthors, 2008: Air–sea interaction over ocean fronts and eddies. Dyn. Atmos. Oceans, 45, 274319, https://doi.org/10.1016/j.dynatmoce.2008.01.001.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Small, R. J., R. A. Tomas, and F. O. Bryan, 2014: Storm track response to ocean fronts in a global high-resolution climate model. Climate Dyn., 43, 805828, https://doi.org/10.1007/s00382-013-1980-9.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Souza, J. M. A. C., C. de Boyer Montégut, C. Cabanes, and P. Klein, 2011: Estimation of the Agulhas ring impacts on meridional heat fluxes and transport using ARGO floats and satellite data. Geophys. Res. Lett., 38, L21602, https://doi.org/10.1029/2011GL049359.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Souza, J. M. A. C., B. Chapron, and E. Autret, 2014: The surface thermal signature and air-sea coupling over the Agulhas rings propagating in the South Atlantic Ocean interior. Ocean Sci., 10, 633644, https://doi.org/10.5194/os-10-633-2014.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Speich, S., J. R. E. Lutjeharms, P. Penven, and B. Blanke, 2006: Role of bathymetry in Agulhas Current configuration and behaviour. Geophys. Res. Lett., 33, L23611, https://doi.org/10.1029/2006GL027157.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Swart, N. C., and J. C. Fyfe, 2012: Observed and simulated changes in the Southern Hemisphere surface westerly wind-stress. Geophys. Res. Lett., 39, L16711, https://doi.org/10.1029/2012GL052810.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Thompson, D. W. J., and S. Solomon, 2002: Interpretation of recent Southern Hemisphere climate change. Science, 296, 895899, https://doi.org/10.1126/science.1069270.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • van Sebille, E., A. Biastoch, P. J. Van Leeuwen, and W. P. M. de Ruijter, 2009: A weaker Agulhas Current leads to more Agulhas leakage. Geophys. Res. Lett., 36, L03601, https://doi.org/10.1029/2008GL036614.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • van Sebille, E., P. J. van Leeuwen, A. Biastoch, and W. P. M. de Ruijter, 2010: Flux comparison of Eulerian and Lagrangian estimates of Agulhas leakage: A case study using a numerical model. Deep-Sea Res. I, 57, 319327, https://doi.org/10.1016/j.dsr.2009.12.006.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • van Sebille, E., M. H. England, J. D. Zika, and B. M. Sloyan, 2012: Tasman leakage in a fine-resolution ocean model. Geophys. Res. Lett., 39, L06601, https://doi.org/10.1029/2012GL051004.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • van Sebille, E., J. Sprintall, F. U. Schwarzkopf, A. Sen Gupta, A. Santoso, M. H. England, A. Biastoch, and C. W. Böning, 2014: Pacific-to-Indian Ocean connectivity: Tasman leakage, Indonesian Throughflow, and the role of ENSO. J. Geophys. Res. Oceans, 119, 13651382, https://doi.org/10.1002/2013JC009525.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • van Sebille, E., and Coauthors, 2018: Lagrangian ocean analysis: Fundamentals and practices. Ocean Modell., 121, 4975, https://doi.org/10.1016/j.ocemod.2017.11.008.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Walker, N. D., 1990: Links between South African summer rainfall and temperature variability of the Agulhas and Benguela Current systems. J. Geophys. Res., 95, 32973319, https://doi.org/10.1029/JC095iC03p03297.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Walker, N. D., and R. D. Mey, 1988: Ocean/atmosphere heat fluxes within the Agulhas Retroflection region. J. Geophys. Res., 93, 15 47315 483, https://doi.org/10.1029/JC093iC12p15473.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Wang, Y., M. J. Olascoaga, and F. J. Beron-Vera, 2015: Coherent water transport across the South Atlantic. Geophys. Res. Lett., 42, 40724079, https://doi.org/10.1002/2015GL064089.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Weijer, W., and E. van Sebille, 2014: Impact of Agulhas leakage on the Atlantic Overturning Circulation in the CCSM4. J. Climate, 27, 101110, https://doi.org/10.1175/JCLI-D-12-00714.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Weijer, W., W. P. M. de Ruijter, A. Sterl, and S. S. Drijfhout, 2002: Response of the Atlantic overturning circulation to South Atlantic sources of buoyancy. Global Planet. Change, 34, 293311, https://doi.org/10.1016/S0921-8181(02)00121-2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Weijer, W., and Coauthors, 2012: The Southern Ocean and its climate in CCSM4. J. Climate, 25, 26522675, https://doi.org/10.1175/JCLI-D-11-00302.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
All Time Past Year Past 30 Days
Abstract Views 0 0 0
Full Text Views 10 10 10
PDF Downloads 8 8 8

Interannual Agulhas Leakage Variability and Its Regional Climate Imprints

View More View Less
  • 1 Rosenstiel School of Marine and Atmospheric Sciences, University of Miami, Miami, Florida
Restricted access

Abstract

We investigate the interannual variability of Agulhas leakage in an ocean-eddy-resolving coupled simulation and characterize its influence on regional climate. Many observational leakage estimates are based on the study of Agulhas rings, whereas recent model studies suggest that rings and eddies carry less than half of leakage transport. While leakage variability is dominated by eddies at seasonal time scales, the noneddy leakage transport is likely to be constrained by large-scale forcing at longer time scales. To investigate this, leakage transport is quantified using an offline Lagrangian particle tracking approach. We decompose the velocity field into eddying and large-scale fields and then recreate a number of total velocity fields by modifying the eddying component to assess the dependence of leakage variability on the eddies. We find that the resulting leakage time series show strong coherence at periods longer than 1000 days and that 50% of the variance at interannual time scales is linked to the smoothed, large-scale field. As shown previously in ocean models, we find Agulhas leakage variability to be related to a meridional shift and/or strengthening of the westerlies. High leakage periods are associated with east–west contrasting patterns of sea surface temperature, surface heat fluxes, and convective rainfall, with positive anomalies over the retroflection region and negative anomalies within the Indian Ocean to the east. High leakage periods are also related to reduced inland convective rainfall over southeastern Africa in austral summer.

© 2018 American Meteorological Society. For information regarding reuse of this content and general copyright information, consult the AMS Copyright Policy (www.ametsoc.org/PUBSReuseLicenses).

Corresponding author: Yu Cheng, yucheng@rsmas.miami.edu

Abstract

We investigate the interannual variability of Agulhas leakage in an ocean-eddy-resolving coupled simulation and characterize its influence on regional climate. Many observational leakage estimates are based on the study of Agulhas rings, whereas recent model studies suggest that rings and eddies carry less than half of leakage transport. While leakage variability is dominated by eddies at seasonal time scales, the noneddy leakage transport is likely to be constrained by large-scale forcing at longer time scales. To investigate this, leakage transport is quantified using an offline Lagrangian particle tracking approach. We decompose the velocity field into eddying and large-scale fields and then recreate a number of total velocity fields by modifying the eddying component to assess the dependence of leakage variability on the eddies. We find that the resulting leakage time series show strong coherence at periods longer than 1000 days and that 50% of the variance at interannual time scales is linked to the smoothed, large-scale field. As shown previously in ocean models, we find Agulhas leakage variability to be related to a meridional shift and/or strengthening of the westerlies. High leakage periods are associated with east–west contrasting patterns of sea surface temperature, surface heat fluxes, and convective rainfall, with positive anomalies over the retroflection region and negative anomalies within the Indian Ocean to the east. High leakage periods are also related to reduced inland convective rainfall over southeastern Africa in austral summer.

© 2018 American Meteorological Society. For information regarding reuse of this content and general copyright information, consult the AMS Copyright Policy (www.ametsoc.org/PUBSReuseLicenses).

Corresponding author: Yu Cheng, yucheng@rsmas.miami.edu
Save