Ellett Array 2024 – an Atlantic Climate and Environment Strategic Science (AtlantiS) & Overturning in the Subpolar North Atlantic Programme (OSNAP) expedition: Cruise report No 301 for RRS Discovery Expedition DY181

Kristin Burmeister, Tiago S. Dotto, Yvonne Firing, N. Penny Holliday

Research output: Book/ReportCommissioned report

Abstract

The primary objective of the expedition was to service the Ellett array of moorings that are deployed across the subpolar North Atlantic to measure the variability of the Atlantic Meridional Overturning Circulation (AMOC). The main measurements required are of temperature, salinity, current speed. On this expedition there are two main groups of moorings measuring these variables: one for the Rockall Trough (RTEB1, RTWB2, RTWB1, RHADCP) and one in the Iceland Basin (IB5, IB4, IB3 – discontinued from 2024 onwards). In addition, a CTD section was undertaken between the Scottish continental shelf and 57°58.84’N, 025°40.57’W, just west of the discontinued mooring IB3.

The specific measurement objectives of the cruise were:
• Recover and redeploy the Ellett array of moorings (RTEB1, RTWB2, RTWB1, RHADCP IB5, IB4, IB3 –IB3 is discontinued from 2024 onwards)

• Four days of DY181 were dedicated to acoustic telemetry testing for WP3 Task B of the RAPID-Evolution project, part of the CCROC program.

• A new drift free pressure sensor was deployed on a lander at the IB4 site and data was downloaded from a similar instrument installed at the RTEB1 side in 2022.

• A mooring to observe particles falling to the sea floor (sediment trap and ADCP) was serviced at the Darwin Mounds Marine protected Area.

• Additional instruments were deployed on moorings to measure oxygen, pH and nutrients.

• To calibrate the moored instruments a number of CTD profiles were made measuring temperature, salinity and oxygen. Water samples were taken and analysed for salinity and oxygen, nutrients, DIC and total alkalinity.

• 6 Argo floats were deployed. These are a part of the international Argo program (http://www.argo.net/).

• Two projects were supported through the AtlantiS berth of opportunity programme: i) Lab-on-Chip sensor was installed to automate water sampling for surface carbon chemistry parameters. ii) A gas-tight carbonate seawater sampler was tested.

• A CTD section was undertaken to survey an eddy close to the Ellett Array sections in the Iceland Basin.
Original languageEnglish
PublisherScottish Association for Marine Science
Number of pages232
Volume301
Publication statusPublished - Jan 2025

Keywords

  • AtlantiS
  • Ellett Array
  • OSNAP
  • AMOC
  • Moorings
  • North Atlantic
  • mooring array
  • CTD
  • Telemetry
  • Autonomy
  • Bottom Pressure Sensors

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