Data Processing of Deep-Sea Measurements Applied to Currents in Abyssal Channels

Frey D. I.

Data processing of hydrographic stations carried out by CTD and LADCP profilers is presented in detail. The CTD and current profiles were measured in the Vema Fracture Zone (11°N) of the Northern Mid-Atlantic Ridge onboard the R/V «Akademik Sergey Vavilov» in September 2015 and April 2016. The goal of these measurements is to study the thermohaline properties and velocities of the Antarctic bottom flow through the Vema FZ. This abyssal channel connects the deep basins of the East and West Atlantic and plays a crucial role in the propagation of Antarctic Bottom Water. We analyzed thermohaline properties of bottom waters at 6 hydrographic stations. In order to remove the effects of horizontal instrument motion from the LADCP measurements the velocity inversion method was applied. Current measurements were corrected by subtracting the tidal velocities using the TPXO model of the Oregon State University. Velocities of the main flow through the northern channel are more than 40 cm/s. In this study we also used the data of digital bathymetry and our echo-sounder measurements. Velocity, temperature and salinity sections across channels are presented for two main parts of the Vema FZ. Known velocities and geometry of the channel allow the calculation of bottom water transports between deep basins of the North Atlantic.

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