VARIABILITY OF WATER MASSES IN BRANSFIELD STRAIT ACCORDING TO AARI OBSERVATIONS IN 2016–2022

  • A. S. Makarov State Scientific Center of the Russian Federation Arctic and Antarctic Research Institute
  • N. N. Antipov State Scientific Center of the Russian Federation Arctic and Antarctic Research Institute
  • S. V. Kashin State Scientific Center of the Russian Federation Arctic and Antarctic Research Institute
  • M. S. Molchanov State Scientific Center of the Russian Federation Arctic and Antarctic Research Institute
DOI 10.29006/1564-2291.JOR-2024.52(2).8
Keywords Bransfield Strait, Antarctic Peninsula, Bransfield Current, water mass, Bransfield Strait deep water, circumpolar deep water, central basin of Bransfield Strait, eastern basin of Bransfield Strait

Abstract

The article presents the results of an analysis of deep-sea oceanographic observation data carried out by AARI scientists in the Bransfield Strait from 2016 to 2022. Bransfield Strait is characterized by complex dynamics, unique water masses, and high bioproductivity. Previous studies made it possible to get an idea of the structure and characteristics of water masses, water circulation, and features of the ice regime. Currently, against the background of observed climate changes, monitoring changes in the state of ocean waters is relevant. The main observations of the AARI vessel are carried out on a stationary section through the central basin of the Bransfield Strait, from Maxwell Bay to the continental slope of the Antarctic Peninsula; a series of observations consists of six realizations of the section with a discreteness of a year. Observations along the section through the eastern basin of the strait were carried out twice, in 2018 and 2022. The interannual variability of the characteristics and dynamics of the water masses of the strait has been established. The temperature and salinity of the bottom layer of Bransfield Strait deep water (BDW), filling the abyssal of the central basin, varied from –1.58 to –1.80 °C and from 34.56 to 34.60 psu, respectively. The trend of warming by more than 0.2 °C (up to –1.578 °C) and desalination by 0.03 psu (up to 34.555 psu), observed in the period 2018–2020, was disrupted by a new cooling of 0.2 °C (up to –1.747 °C) and increase in salinity to 34.59 psu per year. The variability of the characteristics of the Bransfield Strait flow(BF), manifested in fluctuations in the horizontal (from 10 to 20 km) and vertical (from 200 to 550 m) flow dimensions, has been established. A sporadically appearing tongue of deep water from the Antarctic Circumpolar Current below the BF flow was recorded only in data obtained in 2020–2022. During this period, core characteristics showed noticeable variability in core depth (range 320–450 m), temperature (0.4 to 0.9 °C), and salinity (34.58–34.63 psu). A section through the eastern basin of the strait made it possible to detect an increase in the average temperature of the 1200 m thick BDW layer by 0.25 °C over 4 years (with a concomitant increase in salinity by 0.02 psu), reflecting the variability of the climatic scale.

References


  1. Antipov, N. N., V. P. Bunyakin, S. V. Kashin, V. L. Kuznecov, and I. A. Chistyakov, 2016: Okeanograficheskie issledovaniya Yuznogo okeana v yanvare–aprele 2016 goda s borta NES “Akademik Fedorov” (Oceanographic studies of the Southern Ocean in January–April 2016 from the board of the R/V “Academician Fedorov”). Rossijskie polyarnye issledovaniya, 2, 12–15.

  2. Antipov, N. N., V. P. Bunyakin, S. V. Kashin, V. L. Kuznetsov, and I. A. Czystiakov, 2017: Okeanologicheskie issledovaniya Yuznogo okeana v 41-m reise NES “Akademik Fedorov” (Oceanographic studies of the Southern Ocean in the 41st voyage of the R/V “Academician Fedorov”). Rossijskie polyarnye issledovaniya, 3, 8–10.

  3. Antipov, N. N., S. V. Kashin, and M. S. Molchanov, 2021: Glubokovodnye okenologicheskie issledovaniya Yuznogo okeana s borta NES “Akademik Treshnikov” v sezonnyi period 66 RAE (Deep-sea oceanological research of the Southern Ocean from the board of the R/V “Academician Treshnikov” during the seasonal period of the 66th RAE). Rossijskie polyarnye issledovaniya, 3, 9–13.

  4. Antipov, N. N., S. V. Kashin, M. S. Molchanov, and A. A. Fedotova, 2022: Osnovnye rezul’taty okeanologicheskih issledovanij Yuznogo okeana v sezonnyj period 67 RAE (The main results of oceanological studies of the Southern Ocean during the seasonal period of the 67th RAE). Rossijskie polyarnye issledovaniya, 4, 18–24.

  5. Antipov, N. N., S. V. Kashin, and M. S. Molchanov, 2020: Okeanograficheskie issledovaniya YUzhnogo okeana v 14 rejse NES “Akademik Treshnikov” (Oceanographic studies of the Southern Ocean in the 14st voyage of the R/V “Academician Treshnikov”). Rossijskie polyarnye issledovaniya, 2, 32–35.

  6. Krechik, V. A., D. I. Frej, and E. G. Morozov, 2021: Osobennosti cirkulyacii vod v central’noj chasti proliva Bransfilda v yanvare 2020 (Features of circulation in the central part of the Bransfield Strait in January 2020). Doklady Rossijskoj akademii nauk. Nauki o Zemle, 496 (1), 101–105, https://doi.org/10.31857/S2686739721010114.

  7. Morozov, E. G., 2007: Techeniya v prolive Bransfild (Currents in the Bransfield Strait). Doklady Akademii Nauk, 415 (6), 823–825.

  8. Muhamet’yanov, R. Z., D. I. Frej, and E. G. Morozov, 2022: Techeniya v prolive Bransfilda po geostroficheskim raschetam i dannym instrumental’nyh izmerenij (Currents in the Bransfield Strait based on geostrophic calculations and data of instrumental measurements). Izvestiya RAN. Fizika atmosfery i okeana, 58 (5), 583–590, https://doi.org/10.31857/S0002351522050066.

  9. Caspel, van M., H. H. Hellmer, and M. M. Mata, 2017: On the ventilation of Bransfield Strait deep basins. Deep Sea Research Part II: Topical Studies in Oceanography, 149, 25–30, https://doi.org/10.1016/j.dsr2.2017.09.006.

  10. Gomis, D., Marc A. Garcı́a, O. López, and A. Pascual, 2022: Quasi-geostrophic 3D circulation and mass transport in the western Bransfield Strait during Austral summer 1995/96. Deep Sea Research Part II: Topical Studies in Oceanography, 49 (4–5), 603–621, https://doi.org/10.1016/S0967-0645(01)00114-X.

  11. Dotto, T. S., R. Kerr, M. M. Mata, and C. A. E. Garcia, 2016: Multidecadal freshening and lightening in the deep waters of the Bransfield Strait, Antarctica. J. Geophys. Res.: Oceans, 121, 3741–3756, https://doi.org/10.1002/2015JC011228.

  12. Frey, Dmitry I., Viktor A. Krechik, Eugene G. Morozov, Ilya D. Drozd, Alexandra S. Gordey, Alexander A. Latushkin, Olga S. Mekhova, Rinat Z. Mukhametianov, Svetlana A. Murzina, and Sofia A. Ostroumova et al., 2022: Water Exchange between Deep Basins of the Bransfield Strait. Water, 14 (20), 3193, https://doi.org/10.3390/w14203193.

  13. Garcı́a, M. A., C. G. Castro, A. F. Rı́os, M. D. Doval, G. Rosón, D. Gomis, and O. López, 2002: Water masses and distribution of physico-chemical properties in the Western Bransfield Strait and Gerlache Strait during Austral summer 1995/96. Deep Sea Research, Part II: Topical Studies in Oceanography, 49 (4–5), 585–602, https://doi.org/10.1016/S0967-0645(01)00113-8.

  14. Gordey, A. S., D. I. Frey, I. D. Drozd, V. A. Krechik, D. A. Smirnova, S. V. Gladyshev, and E.G.Morozov, 2024: Spatial variability of water mass transports in the Bransfield Strait based on direct current measurements, Deep Sea Research Part I: Oceanographic Research Papers, 207, 104284, https://doi.org/10.1016/j.dsr.2024.104284.

  15. Gordon, A. L., M. Mensch, D. Zhaoqian, W. M. Jr. Smethie, and J. de Bettencourt, 2000: Deep and bottom water of the Bransfield Strait eastern and central basins. J. Geophys. Res.: Oceans, 105, 11337–11346, https://doi:10.1029/2000JC900030.

  16. Gordon, A. L. and W. D. Nowlin, 1978: The Basin Waters of the Bransfield Strait. J. Phys. Oceanogr., 8, 258–264, https://doi.org/10.1175/1520-0485(1978)008<0258:TBWOTB>2.0.CO;2.

  17. Heywood, K. J., A. C. Naveira Garabato, D. P. Stevens, and R. D. Muench, 2004: On the fate of the Antarctic Slope Front and the origin of the Weddell Front. J. Geophys. Res.: Oceans, 109, https://doi.org/10.1029/2003JC002053.

  18. Hirano, D., Y. Kitade, K. I. Ohshima, and Y. Fukamachi, 2015: The role of turbulent mixing in the modified Shelf Water overflows that produce Cape Darnley Bottom Water, J. Geophys. Res. Oceans, 120, 910–922, https://doi.org/10.1002/2014JC010059.

  19. Hofmann, E. E., J. M. Klinck, C. M. Lascara, and D. A. Smith, 2002: Water mass distribution and circulation west of the Antarctic Peninsula and including Bransfield Strait. Foundations for Ecological Research West of the Antarctic Peninsula, 61–80, https://doi.org/10.1029/AR070p0061.

  20. Huhn, O., H. H. Hellmer, M. Rhein, C. Rodehacke, W. Roether, M. P. Schodlok, and M. Schröder, 2008: Evidence of deep- and bottom-water formation in the western Weddell Sea. Deep Sea Res. Part II: Top. Stud. Oceanogr., 55, 1098–1116, https://doi.org/10.1016/j.dsr2.2007.12.015.

  21. Jackett, David R. and Trevor J. McDougall, 1997: A Neutral Density Variable for the World’s Oceans. Journal of Physical Oceanography, 27, 237–263.

  22. López, O., M. A. Garcı́a, D. Gomis, P. Rojas, J. Sospedra, and A. Sánchez-Arcilla, 1999: Hydrographic and hydrodynamic characteristics of the eastern basin of the Bransfield Strait (Antarctica). Deep Sea Research Part I: Oceanographic Research Papers, 46 (10), 1755–1778, https://doi.org/10.1016/S0967-0637(99)00017-5.

  23. McDougall, T. J., 1987: Neutral surfaces, J. Phys. Oceanogr., 17, 950–1964.

  24. Mathias van Caspel, Hartmut H. Hellmer, and M. Mauricio, 2018: Mata On the ventilation of Bransfield Strait deep basins. Deep Sea Research. Part II: Topical Studies in Oceanography, 149, 25–30, https://doi.org/10.1016/j.dsr2.2017.09.006.

  25. Zhou, M., P. P. Niiler, Y. Zhu, and R. D. Dorland, 2006: The western boundary current in the Bransfield Strait, Antarctica. Deep Sea Research Part I: Oceanographic Research Papers, 53(7), 1244–1252, https://doi.org/10.1016/j.dsr.2006.04.003.

  26. Orsi, A. H., G. C. Johnson, and J. L. Bullister, 1999: Circulation, mixing, and production of Antarctic bottom water. Prog. Oceanogr., 43, 55–109.

  27. Poulin, F. J., A. Stegner, M. Herna´ndez-Arencibia, A. Marrero-Di´az, and P. Sangra, 2014: Steep Shelf Stabilization of the Coastal Bransfield Current: Linear Stability Analysis. J. Phys. Oceanogr., 44 (2), 714–732, https://doi.org/10.1175/JPO-D-13-0158.1.

  28. Sangrà, P., C. Gordo, M. Hernández-Arencibia, A. Marrero-Díaz, A. Rodríguez-Santana, A. Stegner, A. Martínez-Marrero, J. L. Pelegrí, and T. Pichon, 2011: The Bransfield Current System. Deep Sea Research Part I: Oceanographic Research Papers, 58 (4), 390–402, https://doi.org/10.1016/j.dsr.2011.01.011.

  29. Strass, V. H., G. Rohardt, T. Kanzow, M. Hoppema, and O. Boebel, 2020: Multidecadal warming and density loss in the deep Weddell Sea. Antarctica. J. Climate, 33, 9863–9881, https://doi.org/10.1175/JCLI-D-20-0271.1.

  30. Tokarczyk, R., 1987: Classification of water masses in the Bransfield Strait and Southern part of the Drake Passage using a method of statistical multidimensional analysis. Polish Polar Research, 8, 333–336.

  31. Whitworth, T., W. D. Nowlin, A. H. Orsi, R. A. Locarnini, and S. G. Smith, 1994: Weddell Sea shelf water in the Bransfield Strait and Weddell-Scotia Confluence. Deep Sea Research Part I: Oceanographic Research Papers, 41 (4), 629–641, https://doi.org/10.1016/0967-0637(94)90046-9.

  32. Whitworth, T., A. H. Orsi, S.-J. Kim, W. D. Nowlin, and R. A. Locarnini, 1998: Water masses and mixing near Antarctic Slope Front. Ocean, Ice and Atmosphere: Interactions at the Antarctic Continental Margin. Antarctic Res. Ser., 75, 1–27.

Published
2024-08-26
Issue
Vol 52 No 2 (2024): Journal of Oceanological Research
Section
Geoecology and marine monitoring

Transfer of copyrights occurs on the basis of a license agreement between the Author and Shirshov Institute of Oceanology, RAS