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RRS Charles Darwin CD139
Cruise summary report
Cruise Info. | |
Ship name (ship code) | RRS Charles Darwin (74AB) |
Cruise identifier | CD139 |
Cruise period | 2002-03-01 — 2002-04-15 |
Status | Completed |
Port of departure | Durban, South Africa |
Port of return | Fremantle, Australia |
Purpose | Research |
Objectives | A modern hydrographic section was made across the Indian Ocean at a latitude of about 32° S during a 46-day voyage from Durban to Fremantle aboard RRS Charles Darwin in March-April 2002.
The principal goal of this work was to measure the flows of mass, heat, freshwater, inorganic and organic nutrients, and carbon dioxide across the southern boundary of the Indian Ocean in order to determine the meridional overturning circulation for the Indian Ocean, to define the heat, freshwater, nutrient and carbon transports across 32° S and to produce overall physical and biogeochemical budgets for the Indian Ocean. A second goal was to examine the climate variability in ocean circulation from comparisons of these new measurements with previous surveys in 1936, 1965, 1987 and 1995. A total of 146 hydrographic stations was made along this transoceanic section. At each station an instrument package consisting principally of a CTD, 3 Lowered ADCPs and 24 10-litre sampling bottles was lowered from the surface down to the ocean bottom to measure temperature, salinity, oxygen and eastward and northward current profiles throughout the water column. On the way back to the surface, 24 water samples were collected at various depths and these samples were analysed on board ship for salinity and oxygen (to calibrate the continuous electronic profiles), for inorganic nutrients, constituents of the carbon system, and chlorofluorocarbons. Samples were also collected and stored for later, shore-based analyses of helium, tritium, and organic nutrients. Throughout the cruise velocity data in the upper few hundred metres of the water column were provided by an ADCP mounted in the ship's hull, meteorological variables were monitored and samples of air and rainfall were periodically collected. In addition, 25 Argo floats were launched along the section to provide continuing profiles over the next 5 years. |
Chief scientist | Harry L Bryden (University of Southampton School of Ocean and Earth Science) |
Cruise report | (4.12 MB) |
Ocean/sea areas | |
General | Indian Ocean |
Track charts | (0.09 MB) |
Measurements | |
Physical oceanography | |
CTD stations | Quantity: number of stations = 146 Description: CTD, water samplers, oxygen sensors, altimeter, x3 LADCPs |
Geochemical tracers (eg freons) | Quantity: number of samples = 2100 Description: Water for analysis of Chlorofluorocarbon |
Chemical oceanography | |
Carbon dioxide | Quantity: number of stations = 146 Description: CO2 component analysis (pH, alkalinity, total inorganic carbon) |
Other dissolved gases | Quantity: number of stations = 24 Description: Analysis of Helium and Tritium |
Phosphate | Quantity: number of stations = 146 Description: Skalar San Plus autoanalysis of phosphate, nitrate, nitrite, silicate |
Nitrate | Quantity: number of stations = 146 Description: Skalar San Plus autoanalysis of phosphate, nitrate, nitrite, silicate |
Nitrite | Quantity: number of stations = 146 Description: Skalar San Plus autoanalysis of phosphate, nitrate, nitrite, silicate |
Silicate | Quantity: number of stations = 146 Description: Skalar San Plus autoanalysis of phosphate, nitrate, nitrite, silicate |
Alkalinity | Quantity: number of stations = 146 Description: CO2 component analysis (pH, alkalinity, total inorganic carbon) |
pH | Quantity: number of stations = 146 Description: CO2 component analysis (pH, alkalinity, total inorganic carbon) |
Biology and fisheries | |
Phytoplankton pigs (eg chlorophyll, fluorescence) | Quantity: number of stations = 45 Description: GFF filtered chlorophyll samples for HPLC |
Data held at BODC | |
Discrete samples | |
146 CTD frame plus rosette sampler | Total dissolved inorganic carbon (TCO2) concentration in the water column Salinity of the water column Phosphate concentration parameters in the water column Temperature of the water column Vertical spatial coordinates Dissolved oxygen parameters in the water column Stable isotopes in water bodies Silicate concentration parameters in the water column Other halocarbon concentrations in water bodies Dissolved noble gas concentration parameters in the water column Density of the water column Nitrate concentration parameters in the water column Radioactivity in water bodies Metadata parameters Chlorofluorocarbon concentrations in the water column Alkalinity, acidity and pH of the water column Chlorophyll pigment concentrations in water bodies |