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RRS James Clark Ross JR19980514 (AMT6, JR32)

Cruise summary report

Cruise Info. 
Ship name (ship code)RRS James Clark Ross (74JC)
Cruise identifierJR19980514 (AMT6, JR32)
Cruise period1998-05-14 — 1998-06-16
StatusCompleted
Port of departureCape Town, South Africa
Port of returnGrimsby, United Kingdom
ObjectivesThe Atlantic Meridional Transect (AMT) programme exploits the passage of the Royal Research Ship (RRS) James Clark Ross (JCR) latitudinally through the Atlantic Ocean between the United Kingdom and the Falkland Islands (approximately 52° N to 52° S) in support of British Antarctic Survey (BAS) research activities in the Antarctic and its environs. In September, the JCR sails southward, sampling the boreal fall and the austral springconditions in the northern hemisphere. The ship's track crosses a range of ecosystems and physicochemical regimes, within which conditions vary from sub-polar to tropical and from eutrophic shelf seas and upwelling systems to oligotrophic and mid-ocean gyres. The JCR provides the ideal platform to measure physical, biological and bio-optical properties and processes through these diverse ecosystems of the North and South Atlantic Oceans.

The AMT programme goals are:
1. To test and refine hypotheses on the responses of oceanic ecosystems and the coupled marine atmosphere to anthropogenically forced environmental change.
2. To develop a holistic research strategy, integrating shipboard measurements, remote sensing and modelling.
3. To provide calibration and validation of new satellite sensors of ocean colour, sea surface temperature, sea surface height and solar radiation.
4. To improve our knowledge of marine biogeochemical processes, ecosystem dynamics, food-webs and fisheries and characterize biogeochemical provinces.
5. To develop coupled physical-biological models of production and ecosystem dynamics.
6. To quantify ocean responses to changes in abundance of radiatively and chemically-active trace gases.

The normal strategy for AMT cruises is set by the requirement for the JCR to make passage between the UK and the FI within the allocated time of 25 d plus 6 d added for scientific research. The geographical range of 50° N, 1° W to 52° S, 58° W, amounts to approximately 7500 miles (13800 km), requiring an average distance of 240 miles per day, or 4° of latitude while on a N-S course (as on the 20° W line). For AMT-6, with a focus on a high productivity, upwelling ecosystems and with 6 d extra for science spread of greatest interest (e.g. the Benguela). Thus the plan was to proceed northwards through the Benguela at only ca 150 miles per day, with more than one station as necessary and make a faster passage through the oligotrophic regions.
Chief scientistJames Aiken (Plymouth Marine Laboratory)
ProjectAMT
Cruise reportRRS James Clark Ross JR19980514 (AMT6, JR32) cruise report jr_amt6.pdf (6.36 MB) 
Ocean/sea areas 
GeneralNorth Atlantic Ocean
South Atlantic Ocean
Track chartsRRS James Clark Ross JR19980514 (AMT6, JR32) cruise track — jr_amt6track.pdf (0.04 MB) 
Measurements 
Physical oceanography 
Water bottle stationsDescription: Water bottle samples were collected using the rosette system. No. of samples not noted.
CTD stationsDescription: CTD station samples were collected. No. of samples not noted.
Optics (eg underwater light levels)Description: Optical measurements were taken with SeaOPS, SeaFALLS, LoCNESS and miniNESS. No. of measurements not noted.
Biology and fisheries 
Primary productivityDescription: Data on phytoplankton pigments and species, primary productivity and zooplankton was gathered. No. of samples not noted.
PhytoplanktonDescription: Data on phytoplankton pigments and species, primary productivity and zooplankton was gathered. No. of samples not noted.
ZooplanktonDescription: Data on phytoplankton pigments and species, primary productivity and zooplankton was gathered. No. of samples not noted.
Data held at BODC Get data
Discrete samples 
52  CTD frame plus rosette samplerTransmittance and attenuance of the water column
Total dissolved inorganic carbon (TCO2) concentration in the water column
Particulate total and organic nitrogen concentrations in the water column
Nitrite concentration parameters in the water column
Carotenoid and flavenoid pigment concentrations in water bodies
Total metal concentrations in water bodies
Phytoplankton taxonomic abundance in water bodies
Phosphate concentration parameters in the water column
Salinity of the water column
Dissolved oxygen parameters in the water column
Temperature of the water column
Bacteria non taxonomy-related biomass expressed as carbon per unit volume of the water column
Phytoplankton taxonomic biomass in water bodies
Bacteria generic abundance in water bodies
Silicate concentration parameters in the water column
Visible waveband radiance and irradiance measurements in the water column
Ammonium and ammonia concentration parameters in water bodies
Plankton abundance per unit volume of the water column
Density of the water column
Plankton biomass expressed as carbon per unit volume of the water column
Raw light meter output
Nitrate concentration parameters in the water column
Metadata parameters
Raw fluorometer output
Oxygen production and respiration in the water column
Dissolved metal concentrations in the water column
Light absorption in the water column
Primary production in the water column
Particulate total and organic carbon concentrations in the water column
Chlorophyll pigment concentrations in water bodies
77  Expendable BathythermographTemperature of the water column
324  Sample taken from ship's non-toxic supplyParticulate total and organic nitrogen concentrations in the water column
Carotenoid and flavenoid pigment concentrations in water bodies
Phytoplankton taxonomic abundance in water bodies
Bacteria non taxonomy-related biomass expressed as carbon per unit volume of the water column
Phytoplankton taxonomic biomass in water bodies
Bacteria generic abundance in water bodies
Plankton abundance per unit volume of the water column
Plankton biomass expressed as carbon per unit volume of the water column
Light absorption in the water column
Particulate total and organic carbon concentrations in the water column
Chlorophyll pigment concentrations in water bodies
8  Surface water sample collected by a bucket on a ropeTotal dissolved inorganic carbon (TCO2) concentration in the water column
Carotenoid and flavenoid pigment concentrations in water bodies
Phytoplankton taxonomic abundance in water bodies
Bacteria non taxonomy-related biomass expressed as carbon per unit volume of the water column
Phytoplankton taxonomic biomass in water bodies
Bacteria generic abundance in water bodies
Plankton abundance per unit volume of the water column
Plankton biomass expressed as carbon per unit volume of the water column
Oxygen production and respiration in the water column
Chlorophyll pigment concentrations in water bodies
49  WP-2 zooplankton net