On spreading of Antarctic Bottom Water in fracture zones of the Mid-Atlantic Ridge at 7–8°N

Abstract

A Data-Interpolating Variational Analysis in n-dimensions was used to describe a potential temperature distribution in the bottom layer of the fracture zones of the Mid-Atlantic Ridge at 7–8°N. This analysis was based on a new digital terrain model obtained by supplementing the STRM15+ bathymetry data with multibeam echo sounding data from the 33rd cruise of the research vessel Akademik Nikolaj Strakhov (2016) and oceanological data from the World Ocean Database, supplemented with CTD profiles and reversing thermometer data measured in scientific cruises of the Shirshov Institute of Oceanology, Russian Academy of Sciences in 2014–2016. A 2D model of near-bottom potential temperature distribution in the study area was calculated based on the analysis. The model allows us to propose the Antarctic Bottom Water propagation pattern through the Doldrums, Vernadsky, and Pushcharovsky fracture zones. It is shown that bottom water warms up when passing fracture zones from 1.4°C in Pushcharovsky Fracture Zone up to 1.6–1.7°C in Vernadsky Fracture Zone. Bottom water from Pushcharovsky and Vernadsky fractures propagates in two directions. Northernly, it propagates to the Doldrums Fracture Zone, where its temperature reaches about 1.9–2.0°C. Easterly, it flows along Pushcharovsky Fracture Zone and raising the temperature up to 1.8–2.0°C. We propose the absence of Antarctic Bottom Water's overflow with a temperature less than 1.8°C to the East Atlantic in the study area.