An expedition of the Shirshov Institute of Oceanology of RAS lasting almost 3 months took place on the RV Akademik Mstislav Keldysh and ended in the port of Kaliningrad on February 25, 2024.

Scientists have made hydrological measurements for the first time in the Vidal Abyssal Channel northwest of the Vema Fracture Zone. Soundings were carried out with profilers of temperature, salinity and current speed. This channel records the flow of Antarctic bottom water, which then fills the entire North American Basin and the deep-sea basin of Puerto Rico, where the greatest depth of the Atlantic is located. The depth difference in the studied channel, which was about 800 km long and up to 3 km wide, ranged from 5200 to 5800 m. Measurements were carried out along the channel and on three cross sections. Previously, no hydrological measurements were carried out in this channel.

After this, work continued in the Vema Fracture Zone. In addition to detailed studies conducted in November 2022, stations were made where Antarctic bottom water flows into the fracture and continued along the fracture. Bottom water flows along the 800 km long the Vema Fracture and fills all the deep-sea basins of the Northeast Atlantic.

The expedition's work ended with the study of the North Equatorial Current.

A total of 125 sounding stations were completed, 78 of which were deep-sea (at depths of more than 5000 m).

In addition to measuring temperature, salinity and current speed in the study areas, oceanologists carried out analyzes of dissolved oxygen, silicate and nitrate content, pH, alkalinity, performed measurements necessary to determine optical parameters and chlorophyll content, and determined current speeds.

The studies carried out made it possible to obtain experimental data on three-dimensional ocean circulation in this part of the abyssal depths of the Atlantic, which is necessary for understanding the processes occurring in the inaccessible depths of the ocean. The results will add essential data to global circulation models to estimate mean ocean state and variability on decadal scales. These data are needed for climate change assessments and forecasts.

In addition to the Institute of Oceanology, employees of the Pacific Oceanological Institute of the Far Eastern Branch of the Russian Academy of Sciences and the Institute of Hydrodynamics of the SB RAS took part in the voyage.