RRS James Cook JC238

Cruise summary report

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Cruise Info.

Ship name (ship code)

RRS James Cook (740H)

Cruise identifier

JC238

Cruise period

2022-07-12 — 2022-07-31

Status

Completed

Port of departure

Southampton, United Kingdom

Port of return

Southampton, United Kingdom

Purpose

Research

Objectives

The primary objective of the expedition was to service the OSNAP/CLASS 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 and one in the Iceland Basin. In addition, a CTD section was undertaken between the Scottish continental shelf and the mooring IB3.

The expedition had a number of additional objectives:
- Additional instruments were deployed on moorings to measure oxygen and pH.
- 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.
- Three Argo floats were deployed. These are a part of the international Argo program (http://www.argo.net)
- A new drift free pressure sensor was deployed on a lander at the RTEB1 site.
- A mooring to observe particles falling to the sea floor (sediment trap and ADCP) was serviced at the Darwin Mounds Marine Protected Area.

Chief scientist

Ben I Moat (National Oceanography Centre, Southampton), Kristin Burmeister (Scottish Association for Marine Science)

Project

OSNAP; Ellet Array; CLASS

Coordinating body

Natural Environment Research Council (NERC)

Cruise report

(28.72 MB)

Ocean/sea areas

General

North East Atlantic Ocean (limit 40W)

Specific

Rockall Trough, Darwin Mounds MPA, Iceland Basin

Measurements

Physical oceanography

Surface measurements underway (T,S)

Quantity: activity duration in days = 20
Description: Underway measurement 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 = 44
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 = 44
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 = 19
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 = 37
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 = 37
Description: On selected CTD stations samples were taken and stored for later analysis of inorganic nutrients and organic nitrogen

Nitrate

Quantity: number of stations = 37
Description: On selected CTD stations samples were taken and stored for later analysis of inorganic nutrients and organic nitrogen

Nitrite

Quantity: number of stations = 37
Description: On selected CTD stations samples were taken and stored for later analysis of inorganic nutrients and organic nitrogen

Silicate

Quantity: number of stations = 37
Description: On selected CTD stations samples were taken and stored for later analysis of inorganic nutrients and organic nitrogen

Alkalinity

Quantity: number of stations = 19
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

CTD stations

57° 57' 11" N 23° 10' 12" W — Argo autonomous profiling float deployment - NKE-PROVOR P44043-21UK004, 0-2000m

CTD stations

57° 57' 42" N 23° 10' 18" W — Argo autonomous profiling float deployment - SBS-NAVIS F1101, 0-2000m

CTD stations

57° 18' 17" N 10° 24' 0" W — Argo autonomous profiling float deployment - SBS-NAVIS F1102, 0-2000m