RRS Discovery DY146

Cruise summary report

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Cruise Info.

Ship name (ship code)

RRS Discovery (74EQ)

Cruise identifier

DY146

Cruise period

2022-02-09 — 2022-03-09

Status

Completed

Port of departure

Southampton, United Kingdom

Port of return

Southampton, United Kingdom

Purpose

Research

Objectives

The primary objective of the cruise was to service the RAPID 26*N array of moorings that is deployed across the subtropical Atlantic to measure the variability of the Atlantic Meridional Overturning Circulation (AMOC). The main measurements required are of temperature, salinity, current speed and bottom pressure. There are two main groups of moorings measuring these variables: one for the eastern boundary and one at the western boundary. This cruise focused on the eastern boundary array. In addition, the cruise had a number of further objectives:
- To improve understanding of the meridional transport of carbon and nutrients by the ocean additional instruments were deployed on moorings to measure oxygen, pH and pCO2, total alkalinity, nitrate and phosphate.
- 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, oxygen. Some samples will later be analysed for dissolved inorganic carbon, total alkalinity, inorganic nutrients and organic nitrogen.
- 5 standard Argo floats were deployed. These are a part of the international Argo program (http://www.argo.net).
- 3 Biogeochemical Argo floats were deployed. These are part of the biogeochemical Argo program (https://biogeochemical-argo.org) and extension of the existing Argo program.
- Sampling of the carbon and nutrient properties of the ocean’s surface microlayer by scientists from the Lyell Centre at the Heriot-Watt University,
- Deployment of a miniboat built and designed by students at King Edwards school in Southampton in collaboration with NOCS and https://educationalpassages.org

Chief scientist

Dafydd G Evans (National Oceanography Centre, Southampton)

Project

RAPID Climate Change - Atlantic Meridional Overturning Circulation

Cruise report

(30.88 MB)

Ocean/sea areas

General

North East Atlantic Ocean (limit 40W)

Specific

Subtropical Atlantic

Track charts

(1.06 MB)

Measurements

Physical oceanography

Surface measurements underway (T,S)

Quantity: activity duration in days = 28
Description: Underway measurements of meteorological variables (wind speed and direction, air temperature and humidity, surface pressure and irradiance); surface (5m) temperature and salinity; subsurface currents from 150kHz and 75 kHz ADCPs and bathymetry from single and multi-beam echo sounders.

CTD stations

Quantity: number of stations = 25
Description: CTD stations, vertical profiles of conductivity, temperature, pressure and oxygen. Samples were taken for calibration of salinity and oxygen

Current profiler (eg ADCP)

Chemical oceanography

Oxygen

Quantity: number of stations = 25
Description: CTD stations, vertical profiles of conductivity, temperature, pressure and oxygen. Samples were taken for calibration of salinity and oxygen

Carbon dioxide

Quantity: number of stations = 20
Description: On selected CTD stations samples were taken and stored for later analysis of dissolved inorganic carbon, and total alkalinity

Phosphate

Quantity: number of stations = 20
Description: On selected CTD stations samples were taken and stored for later analysis of inorganic nutrients and organic nitrogen

Total - P

Quantity: number of stations = 20
Description: On selected CTD stations samples were taken and stored for later analysis of inorganic nutrients and organic nitrogen

Nitrate

Quantity: number of stations = 20
Description: On selected CTD stations samples were taken and stored for later analysis of inorganic nutrients and organic nitrogen

Nitrite

Quantity: number of stations = 20
Description: On selected CTD stations samples were taken and stored for later analysis of inorganic nutrients and organic nitrogen

Silicate

Quantity: number of stations = 20
Description: On selected CTD stations samples were taken and stored for later analysis of inorganic nutrients and organic nitrogen

Quantity: number of stations = 20
Description: On selected CTD stations samples were taken and stored for later analysis of dissolved inorganic carbon, and total alkalinity

Meteorology

Incident radiation

Routine standard measurements

Geology and geophysics

Single-beam echosounding

Multi-beam echosounding

Moorings, landers, buoys

Physical oceanography

Optics (eg underwater light levels)

37° 1' 0" N 13° 14' 12" W — Argo autonomous profiling float deployment BGC Argo 3; 21003

Optics (eg underwater light levels)

34° 43' 47" N 12° 40' 23" W — Argo autonomous profiling float deployment BGC Argo 2; 21002

Optics (eg underwater light levels)

27° 11' 12" N 21° 59' 23" W — Argo autonomous profiling float deployment BGC Argo 1; 21001

Current meters

27° 48' 29" N 13° 44' 53" W — 13 CTD, 3 Oxygen, 4 current meters, 50-1400m, Recovery only

Current meters

27° 48' 29" N 13° 44' 53" W — 13 CTD, 4 oxygen, 4 current meters, 3 pH, 1 pCO2, TA, Nitrate, Phosphate, 50-1400m, Deployment only

Neutrally buoyant floats

34° 43' 47" N 12° 40' 23" W — Argo autonomous profiling float deployment 4; S/N 9189

Neutrally buoyant floats

27° 11' 5" N 21° 59' 30" W — Argo autonomous profiling float deployment 1; S/N 5561

Neutrally buoyant floats

37° 1' 5" N 13° 14' 17" W — Argo autonomous profiling float deployment 5; S/N 9188

Neutrally buoyant floats

24° 56' 17" N 21° 16' 11" W — Argo autonomous profiling float deployment 3; S/N 9195

Neutrally buoyant floats

23° 45' 47" N 24° 9' 11" W — Argo autonomous profiling float deployment 2; S/N 9194

Neutrally buoyant floats

27° 11' 12" N 21° 59' 23" W — Argo autonomous profiling float deployment BGC Argo 1; 21001

Neutrally buoyant floats

37° 1' 0" N 13° 14' 12" W — Argo autonomous profiling float deployment BGC Argo 3; 21003

Neutrally buoyant floats

34° 43' 47" N 12° 40' 23" W — Argo autonomous profiling float deployment BGC Argo 2; 21002

Sea level (inc. bot. press., inverted echosounder)

27° 51' 6" N 13° 32' 23" W — 4 bottom pressure recorders, 1035 m Recovery only

Sea level (inc. bot. press., inverted echosounder)

23° 46' 23" N 24° 9' 29" W — 1 bottom pressure recorder 5000 m Recovery only

Sea level (inc. bot. press., inverted echosounder)

27° 13' 0" N 15° 25' 59" W — 2 bottom pressure recorders, 3000 m. Deployed and recovered.

Sea level (inc. bot. press., inverted echosounder)

23° 47' 53" N 24° 7' 41" W — 4 bottom pressure recorders 5000 m Recovery only