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

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

Published:2024-08-26 Issue:2 Volume:52 Page:145-168
ISSN:1564-2291
Container-title:Journal of Oceanological Research
language:
Short-container-title:JOR

Author:

Makarov A. S.¹,Antipov N. N.¹,Kashin S. V.¹,Molchanov M. S.¹

Affiliation:

1. State Scientific Center of the Russian Federation Arctic and Antarctic Research Institute

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.

Publisher

P.P. Shirshov Institute of Oceanology, RAS

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