RAPID report for research expedition DY146. 4 February – 9 March 2022, RRS Discovery. Research Expedition Report No. 76

The purpose of RRS Discovery research expedition DY146 was to refurbish the eastern boundary portion of the RAPID 26°N array of moorings that span the Atlantic from the Bahamas to the Canary Islands. The expedition started in Southampton on 4 February 2022 and ended on 9 March 2022 in 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 RAPIDMOCHA-WBTS array is a joint UK- US programme. During DY146 moorings were removed at sites: EB1, EBHi and EBH4. Moorings were serviced at sites: EBH1, EBH2 and EBH3. Moorings were equipped with instruments to measure temperature, conductivity and pressure, and a number of moorings were also equipped with current meters and/or biogeochemical sensors, including oxygen, carbon and nutrient sensors. 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).