RRS James Clark Ross JR20120327 (JR254E, JR257, JR272A)

Cruise summary report

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Cruise Info.

Ship name (ship code)

RRS James Clark Ross (74JC)

Cruise identifier

JR20120327 (JR254E, JR257, JR272A)

Cruise period

2012-03-27 — 2012-04-24

Status

Completed

Port of departure

Stanley, Falkland Islands (Malvinas)

Port of return

Stanley, Falkland Islands (Malvinas)

Purpose

Research

Objectives

JR272A cruise objectives were to re-occupy a CTD transect from the Northwest Weddell Sea to South Georgia to study the properties of bottom water as it leaves the Weddell Sea and enters the Scotia Sea. This is part of BAS Polar Oceans core science. The end of the transect close to South Georgia was not completed but there was no sign of bottom water by the point we finished the transect. A mooring was also deployed in South Orkney trough to add to an existing array. A quick (about 6 hours) CTD survey of Cumberland Bay was also completed.

JR257 cruise objectives were to collect a suite of cores made up of diatom- and carbonate-rich sediments from the Polar Front Zone of the SW Atlantic to reconstruct past changes in oceanographic conditions and frontal migrations. The SW Atlantic region is particularly crucial in climate studies as it exerts a disproportionately large influence on Southern Ocean circulation and modification of deep waters. This work is part of the marine component of the Chemistry and Past Climate core science programme and cores collected on this cruise will help determine the role of the Southern Ocean in climate change. Unfortunately, changes to the schedule and the forecasted weather prevented us from exploring the sea mounts in the Georgia Basin for sediments but we were able to collect a promising suite of cores with varying amounts of carbonate material in them from the Falkland Plateau, the North Scotia Ridge (NSR) and the South Georgia continental shelf.

JR254E cruise was dedicated to WAGES (Waves, Aerosols and Gas Exchanges Study),which is a joint project of the National Oceanographic Centre-Southampton and the University of Leeds and is a follow-on from the UK-SOLAS, HiWASE, SEASAW and DOGEE projects.

Throughout the cruise, direct measurements were performed with free drifting and tethered SPAR buoys and also from the ship's underway system. The buoys were deployed in different wind and wave conditions which is essential to improve the parameterisation in terms of mean meteorological and sea-state variables.

An acoustic resonator designed to study bubble size distributions was mounted on one of the SPAR buoys and several deployments were also performed. This line of work has been developed by the University of Southampton.

Chief scientist

Claire S Allen (British Antarctic Survey), Hugh J Venables (British Antarctic Survey), Margaret J Yelland (National Oceanography Centre, Southampton)

Project

BAS Polar Oceans; Waves, Aerosols and Gas Exchange Study (WAGES); Chemistry and Past Climate

Coordinating body

Natural Environment Research Council (NERC)

Cruise report

(3.05 MB)

(0.96 MB)

Ocean/sea areas

General

Southern Ocean

Specific

Wedell Sea, Scotia Sea, Royal Bay (South Georgia) and Cumberland Bay (South Georgia)

Track charts

(0.20 MB)

(0.13 MB)

Measurements

Physical oceanography

Surface measurements underway (T,S)

Quantity: activity duration in days = 28
Description: Underway measurements of water temperature, conductivity, chlorophyll

Water bottle stations

Quantity: number of samples = 256
Description: Water samples collected from CTD bottles to determine salinity

CTD stations

Quantity: number of profiles = 38
Description: CTD casts

Current profiler (eg ADCP)

Quantity: activity duration in days = 28
Description: Current measurements with the vessel-mounted ADCP

Current profiler (eg ADCP)

Quantity: number of profiles = 37
Description: Vertical current profiles from LADCP mounted on the CTD frame

Other physical oceanographic measurements

Quantity: number of samples = 87
Description: Water samples collected from the underway system to determine salinity

Chemical oceanography

Other dissolved gases

Quantity: activity duration in days = 28
Description: pCO2 underway measurements

Biology and fisheries

Biochemical measurements (eg lipids, amino acids)

Quantity: number of samples = 30
Description: Water samples collected from CTD bottles to determine biomarker proxies

Biochemical measurements (eg lipids, amino acids)

Quantity: number of samples = 15
Description: Underway water samples to determine biomarker proxies

Meteorology

Routine standard measurements

Quantity: activity duration in days = 28
Description: Underway measurements of air temperature, pressure, relative humidity, photosynthetically active radiation, active radiation, wind speed and velocity

Geology and geophysics

Core - soft bottom

Quantity: number of deployments = 9
Description: Box core

Core - soft bottom

Quantity: number of deployments = 19
Description: Gravity core

Single-beam echosounding

Quantity: activity duration in days = 28
Description: Single Beam echosounder

Multi-beam echosounding

Quantity: activity duration in days = 28
Description: Multi-beam echosounder

Moorings, landers, buoys

Physical oceanography

Current meters

60° 33' 44" S 41° 37' 55" W — The mooring was deployed with two aquadopps' measuring current direction, velocity components, temperature, pressure and tilt and a SBE37 measuring temperature and conductivity. Water depths for each instrument are as follow: SBE37- 2290 m, aquadopp 2259 m, aquadopp- 2009 m. Deployment date was 02Apr2012 at 19:31 UTC on the eastern side of Orkney Passage