RRS Discovery Cruise DY129, 8 December 2020 - 26 January 2021, RAPID cruise report for Cruise DY129

The purpose of RRS Discovery cruise DY129 was to refurbish the RAPID 26°N array of moorings that span the Atlantic from the Bahamas to the Canary Islands. The cruise started in Southampton on Tuesday 8th December 2020 and ended on Tuesday 26th January 2021 at Southampton, UK. The moorings are part of a purposeful Atlantic wide array that observes the Atlantic Meridional Overturning Circulation and the associated heat and freshwater transports. The RAPID-MOCHA-WBTS array is a joint UK- US programme. During DY129 moorings were removed at sites: MAR3, MAR3L, NOG, MAR1, MAR0 and WB6. Moorings were serviced at sites: WB4, WB4L, WBH2, WB2, WB2L, WB1, WBADCP and WBAL. Sites with suffix ‘L’ denote landers fitted with bottom pressure recorders. Moorings were equipped with instruments to measure temperature, conductivity and pressure, and a number of moorings were also equipped with current meters and/or oxygen sensors. Chemical sensors used in the ABC fluxes project were recovered and not redeployed. The RAPID telemetry system deployed adjacent to mooring WB2 was recovered. CTD stations were conducted throughout the cruise for purposes of providing pre- and post- deployment calibrations for mooring instrumentation (including oxygen and carbonate chemistry sampling). Shipboard underway measurements were systematically logged, processed and calibrated, including: surface meteorology, 5m depth sea temperatures and salinities, water depth, and navigation. Water velocity profiles from 15 m to approximately 800 m depth were obtained using two vessel mounted Acoustic Doppler Current Profilers (one 75 kHz and one 150 kHz).