RRS Discovery DY129

Cruise summary report

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Cruise Info.

Ship name (ship code)

RRS Discovery (74EQ)

Cruise identifier

DY129

Cruise period

2020-12-08 — 2021-01-26

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 26N 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 three main groups of moorings measuring these variables: one for the eastern boundary, one over the mid-Atlantic ridge and one at the western boundary.
In additional the cruise had a number of additional objectives:
- To improve understanding of the meridional transport of carbon by the ocean additional instruments were deployed on moorings to measure oxygen, and two autonomous water samplers were also deployed one of which were paired with pH and pCO2 sensors
- 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. Some samples will later be analysed for dissolved inorganic carbon, total alkalinity, inorganic nutrients and organic nitrogen.
- Five Argo floats were deployed including 1 deep Argo float. These are a part of the international Argo program (http://www.argo.net/).
- Sediment traps were serviced east of the mid-Atlantic ridge for a program of sustained observations.

Chief scientist

Ben I Moat (National Oceanography Centre, Southampton)

Project

RAPID Climate Change - Atlantic Meridional Overturning Circulation

Coordinating body

National Oceanography Centre (NOC)

Cruise report

(44.83 MB)

Ocean/sea areas

General

North Atlantic Ocean

Measurements

Physical oceanography

Surface measurements underway (T,S)

Quantity: activity duration in days = 40
Description: Underway measurements were made 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 = 19
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 = 19
Description: CTD stations, vertical profiles of conductivity, temperature, pressure and oxygen. Samples were taken for calibration of salinity and oxygen

Oxygen

Quantity: activity duration in days = 14
Description: Underway measurement of, Ph, Oxygen from a depth of 5m. Daily Oxygen samples taken.

Carbon dioxide

Quantity: activity duration in days = 30
Description: Underway samples of Alkalinity, Carbon and Nutrients collected from a depth of 5m. Underway measurement of, pCo2 from a depth of 5m.

Carbon dioxide

Quantity: number of stations = 4
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 = 5
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 = 5
Description: On selected CTD stations samples were taken and stored for later analysis of inorganic nutrients and organic nitrogen

Nitrate

Quantity: number of stations = 5
Description: On selected CTD stations samples were taken and stored for later analysis of inorganic nutrients and organic nitrogen

Nitrite

Quantity: number of stations = 5
Description: On selected CTD stations samples were taken and stored for later analysis of inorganic nutrients and organic nitrogen

Silicate

Quantity: number of stations = 5
Description: On selected CTD stations samples were taken and stored for later analysis of inorganic nutrients and organic nitrogen

Alkalinity

Quantity: activity duration in days = 30
Description: Underway samples of Alkalinity, Carbon and Nutrients collected from a depth of 5m. Underway measurement of, pCo2 from a depth of 5m.

Quantity: number of stations = 4
Description: On selected CTD stations samples were taken and stored for later analysis of dissolved inorganic carbon, and total alkalinity

Quantity: activity duration in days = 14
Description: Underway measurement of, Ph, Oxygen from a depth of 5m. Daily Oxygen samples taken.

Other chemical oceanographic measurements

Quantity: activity duration in days = 30
Description: Underway samples of Alkalinity, Carbon and Nutrients collected from a depth of 5m. Underway measurement of, pCo2 from a depth of 5m.

Meteorology

Incident radiation

Routine standard measurements

Geology and geophysics

Single-beam echosounding

Multi-beam echosounding

Moorings, landers, buoys

Physical oceanography