• Argo, 2000: Argo float data and metadata from Global Data Assembly Centre (Argo GDAC). SEANOE, accessed 9 March 2020, https://doi.org/10.17882/42182.

    • Crossref
    • Export Citation
  • Armi, L., 1978: Some evidence for boundary mixing in the deep ocean. J. Geophys. Res., 83, 19711979, https://doi.org/10.1029/JC083iC04p01971.

  • Armi, L., D. Hebert, N. Oakey, J. F. Price, P. L. Richardson, H. T. Rossby, and B. Ruddick, 1989: Two years in the life of a Mediterranean salt lens. J. Phys. Oceanogr., 19, 354370, https://doi.org/10.1175/1520-0485(1989)019<0354:TYITLO>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Baird, M. E., and K. R. Ridgway, 2012: The southward transport of sub-mesoscale lenses of Bass Strait Water in the centre of anti-cyclonic mesoscale eddies. Geophys. Res. Lett., 39, L02603, https://doi.org/10.1029/2011GL050643.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Belkin, I., A. Foppert, T. Rossby, S. Fontana, and C. Kincaid, 2020: A double-thermostad warm-core ring of the Gulf Stream. J. Phys. Oceanogr., 50, 489507, https://doi.org/10.1175/JPO-D-18-0275.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Bosse, A., P. Testor, L. Mortier, L. Prieur, V. Taillandier, F. d’Ortenzio, and L. Coppola, 2015: Spreading of Levantine Intermediate Waters by submesoscale coherent vortices in the northwestern Mediterranean Sea as observed with gliders. J. Geophys. Res. Oceans, 120, 15991622, https://doi.org/10.1002/2014JC010263.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Bosse, A., and et al. , 2016: Scales and dynamics of submesoscale coherent vortices formed by deep convection in the northwestern Mediterranean Sea. J. Geophys. Res. Oceans, 121, 77167742, https://doi.org/10.1002/2016JC012144.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Bosse, A., I. Fer, J. M. Lilly, and H. Søiland, 2019: Dynamical controls on the longevity of a non-linear vortex: The case of the Lofoten Basin eddy. Sci. Rep., 9, 13448, https://doi.org/10.1038/s41598-019-49599-8.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Bower, A. S., R. M. Hendry, D. E. Amrhein, and J. M. Lilly, 2013: Direct observations of formation and propagation of subpolar eddies into the subtropical North Atlantic. Deep-Sea Res. II, 85, 1541, https://doi.org/10.1016/j.dsr2.2012.07.029.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Carmack, E. C., 2007: The alpha/beta ocean distinction: A perspective on freshwater fluxes, convection, nutrients and productivity in high-latitude seas. Deep-Sea Res. II, 54, 25782598, https://doi.org/10.1016/j.dsr2.2007.08.018.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • De Jong, M., A. Bower, and H. H. Furey, 2014: Two years of observations of warm-core anticyclones in the Labrador Sea and their seasonal cycle in heat and salt stratification. J. Phys. Oceanogr., 44, 427444, https://doi.org/10.1175/JPO-D-13-070.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Dewar, W. K., and H. Meng, 1995: The propagation of submesoscale coherent vortices. J. Phys. Oceanogr., 25, 17451770, https://doi.org/10.1175/1520-0485(1995)025<1745:TPOSCV>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Dewey, R. K., 1999: Mooring Design & Dynamics—A Matlab package for designing and analyzing oceanographic moorings. Mar. Models, 1, 103157, https://doi.org/10.1016/S1369-9350(00)00002-X.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Donohue, K., D. R. Watts, K. Tracey, M. Wimbush, and S. Jayne, 2008: Program studies the Kuroshio extension. Eos, Trans. Amer. Geophys. Union, 89, 161162, https://doi.org/10.1029/2008EO170002.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Dugan, J. P., R. R. Mied, P. C. Mignerey, and A. F. Schuetz, 1982: Compact, intrathermocline eddies in the Sargasso Sea. J. Geophys. Res., 87, 385393, https://doi.org/10.1029/JC087iC01p00385.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Ertel, H., 1942: Ein neuer hydrodynamischer Wirbelsatz. Meteor. Z., 59, 277281.

  • Fer, I., A. Bosse, B. Ferron, and P. Bouruet-Aubertot, 2018: The dissipation of kinetic energy in the Lofoten Basin eddy. J. Phys. Oceanogr., 48, 12991316, https://doi.org/10.1175/JPO-D-17-0244.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Fernández-Castro, B., D. G. Evans, E. Frajka-Williams, C. Vic, and A. C. Naveira-Garabato, 2020: Breaking of internal waves and turbulent dissipation in an anticyclonic mode water eddy. J. Phys. Oceanogr., 50, 18931914, https://doi.org/10.1175/JPO-D-19-0168.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Garfield, N., C. A. Collins, R. G. Paquette, and E. Carter, 1999: Lagrangian exploration of the California Undercurrent, 1992–95. J. Phys. Oceanogr., 29, 560583, https://doi.org/10.1175/1520-0485(1999)029<0560:LEOTCU>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Griffiths, R., and E. Hopfinger, 1987: Coalescing of geostrophic vortices. J. Fluid Mech., 178, 7397, https://doi.org/10.1017/S0022112087001125.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Gula, J., T. M. Blacic, and R. E. Todd, 2019: Submesoscale coherent vortices in the Gulf Stream. Geophys. Res. Lett., 46, 27042714, https://doi.org/10.1029/2019GL081919.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Haynes, P. H., and M. E. McIntyre, 1987: On the evolution of vorticity and potential vorticity in the presence of diabetic heating and frictional or other forces. J. Atmos. Sci., 44, 828841, https://doi.org/10.1175/1520-0469(1987)044<0828:OTEOVA>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Hebert, D., N. Oakey, and B. Ruddick, 1990: Evolution of a Mediterranean salt lens: Scalar properties. J. Phys. Oceanogr., 20, 14681483, https://doi.org/10.1175/1520-0485(1990)020<1468:EOAMSL>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Itoh, S., and I. Yasuda, 2010: Water mass structure of warm and cold anticyclonic eddies in the western boundary region of the subarctic North Pacific. J. Phys. Oceanogr., 40, 26242642, https://doi.org/10.1175/2010JPO4475.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Itoh, S., Y. Shimizu, S. I. Ito, and I. Yasuda, 2011: Evolution and decay of a warm-core ring within the western subarctic gyre of the North Pacific, as observed by profiling floats. J. Phys. Oceanogr., 67, 281293, https://doi.org/10.1007/s10872-011-0027-2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Johnson, G. C., and K. E. McTaggart, 2010: Equatorial Pacific 13°C water eddies in the eastern subtropical South Pacific Ocean. J. Phys. Oceanogr., 40, 226236, https://doi.org/10.1175/2009JPO4287.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Kostianoy, A. G., and I. M. Belkin, 1989: A survey of observations on intrathermocline eddies in the world ocean. Mesoscale/Synoptic Coherent Structures in Geophysical Turbulence, J. C. J. Nihoul and B. M. Jamart, Eds., Elsevier Oceanography Series, Vol. 50, Elsevier, 821–841, https://doi.org/10.1016/S0422-9894(08)70223-X.

    • Crossref
    • Export Citation
  • L’Hégaret, P., and et al. , 2014: Evidence of Mediterranean water dipole collision in the Gulf of Cadiz. J. Geophys. Res. Oceans, 119, 53375359, https://doi.org/10.1002/2014JC009972.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Lelong, M. P., Y. Cuypers, and P. Bouruet-Aubertot, 2020: Near-inertial energy propagation inside a Mediterranean anticyclonic eddy. J. Phys. Oceanogr., 50, 22712288, https://doi.org/10.1175/JPO-D-19-0211.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Li, C., Z. Zhang, W. Zhao, and J. Tian, 2017: A statistical study on the subthermocline submesoscale eddies in the northwestern Pacific Ocean based on Argo data. J. Geophys. Res. Oceans, 122, 35863598, https://doi.org/10.1002/2016JC012561.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Lilly, J. M., and P. B. Rhines, 2002: Coherent eddies in the Labrador Sea observed from a mooring. J. Phys. Oceanogr., 32, 585598, https://doi.org/10.1175/1520-0485(2002)032<0585:CEITLS>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Locarnini, R. A., and et al. , 2013: Temperature. Vol. 1, World Ocean Atlas 2013, NOAA Atlas NESDIS 73, 40 pp., http://data.nodc.noaa.gov/woa/WOA13/DOC/woa13_vol1.pdf.

  • Lueck, R., and T. Osborn, 1986: The dissipation of kinetic energy in a warm-core ring. J. Geophys. Res., 91, 803818, https://doi.org/10.1029/JC091iC01p00803.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Ma, X., P. Chang, R. Saravanan, R. Montuoro, J. S. Hsieh, D. Wu, and Z. Jing, 2015: Distant influence of Kuroshio eddies on North Pacific weather patterns? Sci. Rep., 5, 17785, https://doi.org/10.1038/srep17785.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Marez, C. D., X. Carton, S. Corréard, P. L'Hégaret, and M. Morva, 2020: Observations of a deep submesoscale cyclonic vortex in the Arabian Sea. Geophys. Res. Lett., 47, e2020GL087881, https://doi.org/10.1029/2020GL087881..

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Maximenko, N. A., and T. Yamagata, 1995: Submesoscale anomalies in the North Pacific subarctic front. J. Geophys. Res., 100, 18 45918 469, https://doi.org/10.1029/95JC01565.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • McDowell, S. E., and H. T. Rossby, 1978: Mediterranean water: An intense mesoscale eddy off the Bahamas. Science, 202, 10851087, https://doi.org/10.1126/science.202.4372.1085.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • McWilliams, J. C., 1985: Submesoscale, coherent vortices in the ocean. Rev. Geophys., 23, 165182, https://doi.org/10.1029/RG023i002p00165.

  • McWilliams, J. C., 2016: Submesoscale currents in the ocean. Proc. Roy. Soc., 472A, 20160117, https://doi.org/10.1098/rspa.2016.0117.

  • Meunier, T., and et al. , 2018: Intrathermocline eddies embedded within an anticyclonic vortex ring. Geophys. Res. Lett., 45, 76247633, https://doi.org/10.1029/2018GL077527.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Mizuno, K., and W. B. White, 1983: Annual and interannual variability in the Kuroshio Current system. J. Phys. Oceanogr., 13, 18471867, https://doi.org/10.1175/1520-0485(1983)013<1847:AAIVIT>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Molemaker, M. J., J. C. McWilliams, and W. K. Dewar, 2015: Submesoscale instability and generation of mesoscale anticyclones near a separation of the California Undercurrent. J. Phys. Oceanogr., 45, 613629, https://doi.org/10.1175/JPO-D-13-0225.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Nakamura, H., T. Izumi, and T. Sampe, 2002: Interannual and decadal modulations recently observed in the Pacific storm track activity and East Asian winter monsoon. J. Climate, 15, 18551874, https://doi.org/10.1175/1520-0442(2002)015<1855:IADMRO>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Oka, E., K. Toyama, and T. Suga, 2009: Subduction of North Pacific central mode water associated with subsurface mesoscale eddy. Geophys. Res. Lett., 36, L08607, https://doi.org/10.1029/2009GL037540.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Pelland, N., C. C. Eriksen, and C. M. Lee, 2013: Subthermocline eddies over the Washington continental slope as observed by Seagliders, 2003–09. J. Phys. Oceanogr., 43, 20252053, https://doi.org/10.1175/JPO-D-12-086.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Pietri, A., and J. Karstensen, 2018: Dynamical characterization of a low oxygen submesoscale coherent vortex in the eastern North Atlantic Ocean. J. Geophys. Res. Oceans, 123, 20492065, https://doi.org/10.1002/2017JC013177.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Qiu, B., and S. Chen, 2005: Variability of the Kuroshio extension jet, recirculation gyre, and mesoscale eddies on decadal time scales. J. Phys. Oceanogr., 35, 20902103, https://doi.org/10.1175/JPO2807.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Rainville, L., S. Jayne, N. Hogg, and S. Waterman, 2009: KESS data report –WHOI subsurface moorings. WHOI, 15 pp., http://mmmfire.whoi.edu/uskess/data/KESS%20Data%20Report%20%E2%80%93%20WHOI%20subsurface%20moorings.pdf.

  • Rossby, T., C. Flagg, P. Ortner, and C. Hu, 2011: A tale of two eddies: Diagnosing coherent eddies through acoustic remote sensing. J. Geophys. Res., 116, C12017, https://doi.org/10.1029/2011JC007307.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Shapiro, G. I., and S. L. Meschanov, 1991: Distribution and spreading of Red Sea Water and salt lens formation in the northwest Indian Ocean. Deep-Sea Res. I, 38, 2134, https://doi.org/10.1016/0198-0149(91)90052-H.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Shapiro, G. I., W. Zenk, S. L. Meschanov, and K. L. Schultz Tokos, 1995: Self-similarity of the meddy family in the eastern North Atlantic. Oceanol. Acta, 18, 2942.

    • Search Google Scholar
    • Export Citation
  • Spall, M. A., 1995: Frontogenesis, subduction, and cross-front exchange at upper ocean fronts. J. Geophys. Res., 100, 25432557, https://doi.org/10.1029/94JC02860.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Srinivasan, K., J. C. McWilliams, M. J. Molemaker, and R. Barkan, 2019: Submesoscale vortical wakes in the lee of topography. J. Phys. Oceanogr., 49, 19491971, https://doi.org/10.1175/JPO-D-18-0042.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Steinberg, J. M., N. A. Pelland, and C. C. Eriksen, 2019: Observed evolution of a California Undercurrent Eddy. J. Phys. Oceanogr., 49, 649674, https://doi.org/10.1175/JPO-D-18-0033.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Testor, P., and J. C. Gascard, 2003: Large-scale spreading of deep waters in the western Mediterranean Sea by submesoscale coherent eddies. J. Phys. Oceanogr., 33, 7587, https://doi.org/10.1175/1520-0485(2003)033<0075:LSSODW>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Testor, P., and J. C. Gascard, 2006: Post-convection spreading phase in the northwestern Mediterranean Sea. Deep-Sea Res. I, 53, 869893, https://doi.org/10.1016/j.dsr.2006.02.004.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Thomas, L. N., 2008: Formation of intrathermocline eddies at ocean fronts by wind-driven destruction of potential vorticity. Dyn. Atmos. Oceans, 45, 252273, https://doi.org/10.1016/j.dynatmoce.2008.02.002.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Thomsen, S., T. Kanzow, G. Krahmann, R. J. Greatbatch, M. Dengler, and G. Lavik, 2016: The formation of a subsurface anticyclonic eddy in the Peru-Chile Undercurrent and its impact on the near-coastal salinity, oxygen, and nutrient distributions. J. Geophys. Res. Oceans, 121, 476501, https://doi.org/10.1002/2015JC010878.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Timmermans, M. L., J. Toole, A. Proshutinsky, R. Krishfield, and A. Plueddemann, 2008: Eddies in the Canada basin, Arctic Ocean, observed from ice-tethered profilers. J. Phys. Oceanogr., 38, 133145, https://doi.org/10.1175/2007JPO3782.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Yasuda, I., K. Okuda, and M. Hirai, 1992: Evolution of a Kuroshio warm-core ring—Variability of the hydrographic structure. Deep-Sea Res. I, 39, S131S161, https://doi.org/10.1016/S0198-0149(11)80009-9.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Yu, L.-S., A. Bosse, I. Fer, K. A. Orvik, E. M. Bruvik, I. Hessevik, and K. Kvalsund, 2017: The Lofoten Basin eddy: Three years of evolution as observed by Seagliders. J. Geophys. Res. Oceans, 122, 68146834, https://doi.org/10.1002/2017JC012982.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Zhang, Z., P. Li, L. Xu, C. Li, W. Zhao, J. Tian, and T. Qu, 2015: Subthermocline eddies observed by rapid-sampling Argo floats in the subtropical northwestern Pacific Ocean in spring 2014. Geophys. Res. Lett., 42, 64386445, https://doi.org/10.1002/2015GL064601.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Zhang, Z., B. Qiu, J. Tian, W. Zhao, and X. Huang, 2018: Latitude-dependent finescale turbulent shear generations in the Pacific tropical-extratropical upper ocean. Nat. Commun., 9, 4086, https://doi.org/10.1038/s41467-018-06260-8.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Zhang, Z., Z. Liu, K. Richards, G. Shang, W. Zhao, J. Tian, and C. Zhou, 2019: Elevated diapycnal mixing by a subthermocline eddy in the western equatorial Pacific. Geophys. Res. Lett., 46, 26282636, https://doi.org/10.1029/2018GL081512.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Zhang, Z., Y. Zhang, B. Qiu, H. Sasaki, Z. Sun, X. Zhang, W. Zhao, and J. Tian, 2020: Spatiotemporal characteristics and generation mechanisms of submesoscale currents in the northeastern South China Sea revealed by numerical simulations. J. Geophys. Res. Oceans, 125, e2019JC015404, https://doi.org/10.1029/2019JC015404.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Zhang, Z., X. Zhang, B. Qiu, W. Zhao, C. Zhou, X. Huang, and J. Tian, 2021: Submesoscale currents in the subtropical upper ocean observed by long-term high-resolution mooring arrays. J. Phys. Oceanogr., 51, 187206, https://doi.org/10.1175/JPO-D-20-0100.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Zhao, M., and M. L. Timmermans, 2015: Vertical scales and dynamics of eddies in the Arctic Ocean’s Canada basin. J. Geophys. Res. Oceans, 120, 81958209, https://doi.org/10.1002/2015JC011251.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Zweng, M., and et al. , 2013: Salinity. Vol. 2, World Ocean Atlas 2013, NOAA Atlas NESDIS 74, 39 pp., http://data.nodc.noaa.gov/woa/WOA13/DOC/woa13_vol2.pdf.

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Subthermocline Eddies in the Kuroshio Extension Region Observed by Mooring Arrays

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  • 1 Key Laboratory of Physical Oceanography/Institute for Advanced Ocean Science/Frontiers Science Center for Deep Ocean Multispheres and Earth System, Ocean University of China, Qingdao, China
  • | 2 Pilot National Laboratory for Marine Science and Technology (Qingdao), Qingdao, China
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Abstract

Subthermocline eddies (STEs), also termed intrathermocline eddies or submesoscale coherent vortices, are lens-shaped eddies with anomalous water properties located in or below the thermocline. Although STEs have been discovered in many parts of the World Ocean, most of them were observed accidentally in hydrographic profiles, and direct velocity measurements are very rare. In this study, dynamic features of STEs in the Kuroshio Extension (KE) region are examined in detail using concurrent temperature/salinity and velocity measurements from mooring arrays. During the moored observation periods of 2004–06 and 2015–19, 11 single-core STEs, including 8 with warm/salty cores and 3 with cold/fresh cores, were captured. The thermohaline properties in their cores suggest that these STEs may originate from the subarctic front and the upstream Kuroshio south of Japan. The estimated radius of these STEs varied from 8 to 66 km with the mean value of ~30 km. The warm/salty STEs seemed to be larger and rotate faster than the cold/fresh ones. In addition to single-core STEs, a dual-core STE was observed in the KE recirculation region, which showed that the upper cold/fresh cores stacked vertically over the lower warm/salty cores. Based on the observed parameters of the STEs, their Rossby number and Burger number were further estimated, with values up to 0.5 and 1, respectively. Furthermore, a low Richardson number O (0.25) was found at the periphery of these STEs, suggesting that shear instability-induced turbulent mixing may be an erosion route for the STEs.

Supplemental information related to this paper is available at the Journals Online website: https://doi.org/10.1175/JPO-D-20-0047.s1.

© 2021 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: Zhaohui Chen, chenzhaohui@ouc.edu.cn

Abstract

Subthermocline eddies (STEs), also termed intrathermocline eddies or submesoscale coherent vortices, are lens-shaped eddies with anomalous water properties located in or below the thermocline. Although STEs have been discovered in many parts of the World Ocean, most of them were observed accidentally in hydrographic profiles, and direct velocity measurements are very rare. In this study, dynamic features of STEs in the Kuroshio Extension (KE) region are examined in detail using concurrent temperature/salinity and velocity measurements from mooring arrays. During the moored observation periods of 2004–06 and 2015–19, 11 single-core STEs, including 8 with warm/salty cores and 3 with cold/fresh cores, were captured. The thermohaline properties in their cores suggest that these STEs may originate from the subarctic front and the upstream Kuroshio south of Japan. The estimated radius of these STEs varied from 8 to 66 km with the mean value of ~30 km. The warm/salty STEs seemed to be larger and rotate faster than the cold/fresh ones. In addition to single-core STEs, a dual-core STE was observed in the KE recirculation region, which showed that the upper cold/fresh cores stacked vertically over the lower warm/salty cores. Based on the observed parameters of the STEs, their Rossby number and Burger number were further estimated, with values up to 0.5 and 1, respectively. Furthermore, a low Richardson number O (0.25) was found at the periphery of these STEs, suggesting that shear instability-induced turbulent mixing may be an erosion route for the STEs.

Supplemental information related to this paper is available at the Journals Online website: https://doi.org/10.1175/JPO-D-20-0047.s1.

© 2021 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: Zhaohui Chen, chenzhaohui@ouc.edu.cn

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