Nella Dan: SIBEX II Cruise - Oceanographic and nutrient data
Oceanography and nutrient measurements were taken where possible, which was not always at ideal locations. Therefore coverage of the area is not necessarily complete. Nutrient data were only recorded at 44 out of the 64 CTD stations. This cruise is however part of a series of 6 cruises which operate...
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| Format: | Dataset |
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Australian Ocean Data Network
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| Online Access: | https://researchdata.ands.org.au/nella-dan-sibex-oceanographic-nutrient/685378 https://data.aad.gov.au/metadata/records/SIBEX_II_ocean https://data.aad.gov.au/eds/3327/download http://data.aad.gov.au/aadc/metadata/citation.cfm?entry_id=SIBEX_II_ocean |
| Summary: | Oceanography and nutrient measurements were taken where possible, which was not always at ideal locations. Therefore coverage of the area is not necessarily complete. Nutrient data were only recorded at 44 out of the 64 CTD stations. This cruise is however part of a series of 6 cruises which operated in this area, providing data from varying seasons and condition. Data collection: A Neil Brown Mark III CTD (conductivity, temperature, depth probe #2941) system attached to a rosette water sampler (General Oceanics) was used for collecting continuous vertical profiles of conductivity and temperature. Water samples were collected at different depths using the rosette water sampler with 5L Niskin bottles. Measurements were made on the downcast, and water samples collected on the upcast. The water sampling depths were determined depending on the readings made during the downcast. The CTD was lowered at a rate as close to 1 m/sec, and raised between samples at speeds between 1 and 2 m/sec. Conductivity and temperature readings were also made at each water sampling station. 64 CTD stations were taken along a series of transects. Nutrient samples were taken at 44 of the CTD stations. Ship-board processing: 250 mL water sub-samples were filtered through GF/F glass fibre filters, transferred to rinsed polyethylene bottles and immediately frozen. Water samples were analysed on board the ship for salinity and oxygen. Post-ship processing: Oceanography data - Data was initially recorded on audio cassettes, but later replayed to produce digital nine-track magnetic tapes by a PDP 11/23. Data tapes were then processed on a VAX 11/750. For each CTD downcast, an uncalibrated, despiked file was generated, using a recursive filter to compensate for sensor mismatch. The data files were used to generate 2 dbar averages for in situ temperature, salinity, sigma-t, specific volume anomaly and geopotential anomaly. The averages were centred on even, integral depths, and were only calculated when averages contained eight or more valid data points. The temperature and conductivity means were calculated for the interval, and the salinity calculated for the mid point of the pressure interval from the temperature and salinity means. Data processing software was supplied by CSIRO Division of Oceanography. Nutrient data - Analyses was completed by the Australian Government Analytical Laboratories for nitrate, nitrite, silicate, chlorophyll a and other pigments. Nitrite concentrations were found to be insignificant. The complete dataset is logically consistent, as krill and zooplankton hauls and phytoplankton pigment analysis were also obtained at the same sampling sites as the oceanographic and nutrient data. The cruise track was established before the experiment in order to eliminate bias. The oceanographic sampling was done as a supplement to the krill research program and the nutrient sampling to help interpret phytoplankton distribution and abundance, so sampling location and depth were not necessarily selected according to oceanographic or nutrient related considerations. This dataset contains CTD (conductivity, temperature, depth) and nutrient (nitrate, nitrite (insignificant concentrations), phosphate, silicate) data obtained from the Second International BIOMASS Experiment (SIBEX II) cruise of the Nella Dan, during January 1985. This cruise is the fourth in a series of six cruises, conducting a long term field survey on krill and other zooplankton. 64 CTD casts were taken in the Prydz Bay region, and nutrient data were collected at 44 of the stations. Casts were made to 1000 m or to near bottom if shallower. Oceanographic and nutrient sampling was done a supplement to the krill research program, and therefore was not always ideal for oceanographic purposes. The fields in this dataset are: cruise name station number date start time ship name station position cast depth sea bottom depth Depth Nitrate Nitrite Phosphate Silicate Manganese (Mn) Pressure Temperature Salinity Sigma-T Specific Volume Anomaly Geopotential Anomaly Number of samples Temperature Deviation Conductivity Deviation This dataset was updated by Angela McGaffin to include a summary excel file. This download file also contains the original datasets. |
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