EPOC expeditions: 26ºN Eastern Boundary data recovery 2024 (DY174)

Key facts

Dates: 28 March – 4 April 2024

Vessel: RRS Discovery

Lead scientist: Ben Moat (NOC, PI of RAPID project)

Work area: Eastern boundary of the subtropical North Atlantic at the RAPID moorings at 26°N

Key objectives: Recovery of 24 biogeochemical (BGC) sensors (oxygen, pCO2, pH, nitrate, phosphate, alkalinity) after 2-year deployment, and collection of discrete water samples for biogeochemical analysis (as part of a wider RAPID expedition)

EPOC partners involved: WP5

Location of sensors on the eastern boundary
Location of moorings with BGC sensors as part of the RAPID array, superimposed on background oxygen concentration distribution.
Expedition overview

This expedition will allow EPOC researchers to retrieve data from biogeochemical sensors deployed two years ago on moorings at the eastern boundary of the RAPID 26ºN observing array.  The recovered high-resolution biogeochemical sensor data (measuring at 1-24 hour frequency) will be used to help create time-varying biogeochemical parameter distributions for combination with 10-day velocity fields output from RAPID. These will be used to assess the importance of new BGC measurements on reducing the uncertainty of large-scale BGC transport estimates. Currently the latter are based solely on historical discrete water sample data, collected typically on a 5-10 year repeat basis.

A number of the recovered sensors will be refurbished and redeployed on a future AMOC monitoring array expedition.

BGC sensors and frames awaiting deployment
BGC sensors and frames prior to deployment in February 2022. Photo credit: Sara Fowell (NOC, UK)