Water mass-structure and variability of the Kane gap in the equatorial Atlantic ocean

Cover Page

Cite item

Full Text

Open Access Open Access
Restricted Access Access granted
Restricted Access Subscription Access

Abstract

The results of a study of the water mass structure in a poorly studied area of the eastern basin of the Tropical Atlantic (Kane Gap) according to data from the 63rd cruise of P/V “Akademik Ioffe” in 2022 are presented in the paper. Variability of the average monthly characteristics of these waters using the GLORYS12v1 reanalysis for 1993–2022 is shown. Intermediate waters in the section are represented by a mixture of Antarctic intermediate water (AAIW) and Mediterranean water (the share of the latter reaches 34%). It has been established that the North Atlantic Deep Water (NADW) is represented by two layers: the Upper NADW with a maximum of salinity and the Middle NADW with a maximum of oxygen. The bottom water layer contains a mixture of Antarctic Bottom Water (AABW), the Lower and Middle components of the NADW. This mixture, coming primarily from the Vema Fracture zone region, is properly to call Northeast Atlantic Bottom Water (NEABW). Its upper limit corresponded to the isotherm of 1.95°С and the Si/P ratio equal to 33. In this work, using the conservative PO, the proportion of AABW in NEABW, which is about 20%, was calculated. According to the GLORYS12v1 on a seasonal scale in the bottom layer, a significant negative relationship was established between the variability of potential temperature and the meridional speed of currents. Significant trend for an increase in the average annual potential temperature (by 0.06 °C) and a decrease in salinity (by 0.005 psu) in general for the period 1993–2022 was revealed.

Full Text

Restricted Access

About the authors

А. N. Demidov

Lomonosov Moscow State University

Author for correspondence.
Email: tuda@mail.ru

Faculty of Geography

Russian Federation, Moscow

K. V. Artamonova

Lomonosov Moscow State University; Russian Federal Research Institute of Fisheries and Oceanography

Email: tuda@mail.ru

Faculty of Geography

Russian Federation, Moscow; Moscow

S. B. Krasheninnikova

Lomonosov Moscow State University; A.O. Kovalevsky Institute of Biology of the Southern Seas, Russian Academy of Sciences

Email: tuda@mail.ru

Faculty of Geography

Russian Federation, Moscow; Sevastopol

S. А. Dobrolyubov

Lomonosov Moscow State University

Email: tuda@mail.ru

Faculty of Geography, Academician of the RAS

Russian Federation, Moscow

References

  1. Sarafanov A., Sokov A., Demidov A. Water mass characteristics in the equatorial North Atlantic: A section nominally along 6.5N, July 2000 // Journal of Geophysical Research. 2007. 112(C12). C12023. https://doi.org/10.1029/2007JC004222
  2. Andrié C., Ternon J. F., Messias M. J., Memery L., Bourlès B. Chlorofluoromethane distributions in the deep equatorial Atlantic during January– March 1993 // Deep Sea Research Part I: Oceanographic Research Papers. 1998. V. 45. № 6. P. 903–930.
  3. Herrford J., Brandt P., Zenk W. Property changes of deep and bottom waters in the Western Tropical Atlantic // Deep-Sea Research. Part I. 2017. V. 124. P. 103–125.
  4. Liu M., Tanhua T. Water masses in the Atlantic Ocean: characteristics and distributions // Ocean Science. 2021. V. 17. P. 463–486.
  5. Wust G. The stratosphere of the Atlantic Ocean // Wiss. Ergebn. Dtsch. Atlant. Exped. Meteor. 1935. V. 6.
  6. Rhein M., Stramma L., Send U. The Atlantic Deep Western Boundary Current: Water masses and transports near the equator // Journal of Geophysical Research. 1995. 100(C2). 2441. https://doi.org/10.1029/94JC02355
  7. Morozov E. G., Demidov A. N., Tarakanov R. Yu., Zenk W. Abyssal Channels in the Atlantic Ocean. Water Structure and Flows // Springer Science + Business Media. 2010. https://doi.org/10.1007/978-90-481-9358-5
  8. Van Haren H., Morozov E., Gostiaux L., Tarakanov R. Convective and shear‐induced turbulence in the deep Kane Gap // Journal of Geophysical Research: Oceans. 2013. V. 118. № 11. P. 5924–5930. https://doi.org/10.1002/2013JC009282
  9. McCartney M. S., Bennett S. L., Woodgate-Jones M. E. Eastward Flow through the Mid-Atlantic Ridge at 11N and Its Influence on the Abyss of the Eastern Basin // Journal of Physical Oceanography. 1991. 21(8). 1089–1121. https://doi.org/10.1175/1520-0485(1991)021
  10. Сапожников В. В., Агатова А. И., Аржанова Н. В., Мордасова Н. В., Лапина Н. М., Зубаревич В. Л., Лукьянова О. Н., Торгунова Н. И. Руководство по химическому анализу морских и пресных вод при экологическом мониторинге рыбохозяйственных водоёмов и перспективных для промысла районов Мирового океана. М.: Изд-во ВНИРО, 2003. 202 с.
  11. Broecker W. “NO” a conservative water-mass tracer // Earth and Planetary Science Letters. 1974. V. 23. P. 100–107.
  12. Демидов А. Н. О выделении промежуточных и глубинных водных масс в Южной Атлантике // Океанология. 2003. Т. 43. № 2. С. 165–175.
  13. de Carvalho Ferreira M. L., Kerr R. Source water distribution and quantification of North Atlantic deep water and Antarctic bottom water in the Atlantic Ocean // Progress in Oceanography. 2017. V. 153. P. 66–83.
  14. Oudot J., Merlin F. X., Pinvidic P. Weathering rates of oil components in a bioremediation experiment in estuarine sediments // Marine Environmental Research. 1998. V. 45. №. 2. P. 113–125. https://doi.org/10.1016/s0141-1136(97)00024-x
  15. Аржанова Н. В., Артамонова К. В. Гидрохимическая структура вод в районах промысла антарктического криля Euphausia superba Dana // Труды ВНИРО. 2014. Т. 152. С. 118–132.
  16. Van Aken H. M. The Oceanic Thermohaline Circulation: an introduction / Springer Science & Business Media. 2007. V. 39. P. 135–182.
  17. Garcia-Ibanez et al. Structure, transports and transformations of the water masses in the Atlantic Subpolar Gyre // Progress in oceanography. 2015. V. 135. P. 18–36.
  18. Morozov E. G., Tarakanov R. Y., Van Haren H. Transport of Antarctic bottom water through the Kane Gap, tropical NE Atlantic Ocean // Ocean Science. 2013. V. 9. № 5. P. 825–835. https://doi.org/10.5194/os-9-825-2013
  19. Thierry V., Mercier H., Treguier A.-M. Seasonal fluctuations in the deep central equatorial Atlantic Ocean: A data-model comparison // Ocean Dynamics. 2006. V. 56. P. 5–6.
  20. Krasheninnikova S. B., Demidov A. N., Ivanov A. A. Variability of the Characteristics of the Antarctic Bottom Water in the Subtropical North Atlantic // Oceanology. 2021. V. 61. Iss. 2. P. 151–158. https://doi.org/10.1134/S0001437021020090

Supplementary files

Supplementary Files
Action
1. JATS XML
Download
2. Fig. 1. The position of the stations in the 63rd cruise of the R/V Akademik Ioffe (AI-63) in the Kane Passage. a – schematic map of the Kane Passage, red dots – the position of the stations; b – schematic map of the study area with a bottom water circulation scheme. The red square shows the study area, and the dots – the position of the stations, the gray arrows show the circulation scheme of the Antarctic bottom water (ABW) and the Northeast Atlantic Bottom Water (NEABW) according to [7, 9] for the Cape Verde Basin. Black arrows – the path of NEABW to the study area, reconstructed from the GLORYS12v1 reanalysis

Download (691KB)
Indexing metadata
3. Fig. 2. Distributions of potential temperature, °C (a), salinity, eps (b), dissolved oxygen content, μM/kg (c), silicates, μM/kg (d), θ,S-diagram (d), and phosphate content, μM/kg (e) on section AI63 in the Kane Passage. The gray lines show the boundaries of the water masses, the white line in (d) shows the position of Si/P = 33

Download (1MB)
Indexing metadata
4. Fig. 3. Interannual variability of monthly average values ​​of potential temperature (θ, °C) (a), meridional current velocity (V, cm/s) (b) in the Kane Passage based on the GLORYS12v1 ocean reanalysis for all months of 1993–2022. The inset (on the right) shows an enlarged fragment of 2009–2012. Black dots are based on estimates by different authors from Table 4. Gray fill is the standard deviations for the series of monthly average values ​​of the GLORYS12v1 reanalysis, calculated for 11 months using a sliding window (+5 and –5 months from the central value).

Download (239KB)
Indexing metadata
5. Fig. 4. Periodogram of monthly mean series (a) and variability of filtered detrended monthly mean values ​​of meridional current velocity (V, m/s, blue) and potential temperature (θ, °C, red), for periods of 0.5–1 (b); 2–4 years (c), 10–30 years (d) in the Kane Passage based on the GLORYS12v1 ocean reanalysis

Download (344KB)
Indexing metadata

Copyright (c) 2025 Russian Academy of Sciences