Metadata Report for BODC Series Reference Number 1849689

• Metadata Summary

• Problem Reports

• Data Access Policy

• Narrative Documents

• Project Information

• Data Activity or Cruise Information

• Fixed Station Information

• BODC Quality Flags

• SeaDataNet Quality Flags

Metadata Summary

Problem Reports

No Problem Report Found in the Database

Data Access Policy

Open Data supplied by Natural Environment Research Council (NERC)

You must always use the following attribution statement to acknowledge the source of the information: "Contains data supplied by Natural Environment Research Council."

Narrative Documents

Niskin Bottle

The Niskin bottle is a device used by oceanographers to collect subsurface seawater samples. It is a plastic bottle with caps and rubber seals at each end and is deployed with the caps held open, allowing free-flushing of the bottle as it moves through the water column.

Standard Niskin

The standard version of the bottle includes a plastic-coated metal spring or elastic cord running through the interior of the bottle that joins the two caps, and the caps are held open against the spring by plastic lanyards. When the bottle reaches the desired depth the lanyards are released by a pressure-actuated switch, command signal or messenger weight and the caps are forced shut and sealed, trapping the seawater sample.

Lever Action Niskin

The Lever Action Niskin Bottle differs from the standard version, in that the caps are held open during deployment by externally mounted stainless steel springs rather than an internal spring or cord. Lever Action Niskins are recommended for applications where a completely clear sample chamber is critical or for use in deep cold water.

Clean Sampling

A modified version of the standard Niskin bottle has been developed for clean sampling. This is teflon-coated and uses a latex cord to close the caps rather than a metal spring. The clean version of the Levered Action Niskin bottle is also teflon-coated and uses epoxy covered springs in place of the stainless steel springs. These bottles are specifically designed to minimise metal contamination when sampling trace metals.

Deployment

Bottles may be deployed singly clamped to a wire or in groups of up to 48 on a rosette. Standard bottles and Lever Action bottles have a capacity between 1.7 and 30 L. Reversing thermometers may be attached to a spring-loaded disk that rotates through 180° on bottle closure.

D233 Discrete CTD Dissolved Oxygen Sampling Document

Originator's Protocol for Data Acquisition and Analysis

Sample collection and analysis

Discrete oxygen samples were collected from CTD Niskin bottles fired during D233. Duplicate samples (between one and four) were obtained on each cast, typically from the deepest bottles. Oxygen samples were drawn immediately after those collected for CFC analysis. Samples were obtained in clear, pre-calibrated wide-necked glass bottles using a short silicon tube attached to the Niskin. Samples were fixed immediately with precise manganese chloride and alkaline iodide additions, the sample temperature at the time of fixing being recorded using a hand held thermometer. Samples were shaken for approximately 30 seconds on deck and again once the samples had stabilised for 30 minutes in the ship's Constant Temperature Laboratory. Care was taken not to introduce bubbles to the sample at any stage, if this occurred the sample was discarded. Samples were stored underwater prior to analysis.

The samples were analysed onboard using the Winkler whole bottle titration method with amperometric endpoint detection (Culberson and Haung, 1987). The equipment used was supplied by Metrohm. The normality of the thiosulphate titrant was verified with an in-house standard prior to each analytical run and adjustments made accordingly. Blank measurements were also made and accounted for according to WOCE protocols.

A mean difference of 0.457 (+/- 0.282) µmol L^-1 was found between duplicate oxygen pairs sampled on each station, once high duplicate differences had been removed from the data set.

BODC Data Processing Procedures

PSTAR-formatted CTD sample data from this cruise were supplied to BODC during December 1999. The oxygen data were extracted from these files and loaded into BODC's Oracle database. Flags were assigned if values were considered suspect.

Content of data series

References

Culberson, C. H., and Haung, S., (1987). Automated amperometric oxygen titration. Deep Sea Res., 34, 875 - 880.

Smythe-Wright, D., (1999). RRS Discovery Cruise 233, 23 APR - 01 JUN 1998. CHAOS. Cruise Report No. 24 Southampton Oceanography Centre.

Project Information

UK WOCE

The UK made a substantial contribution to the international World Ocean Circulation Experiment (WOCE) project by focusing on two important regions:

1. Southern Ocean - links all the worlds oceans, controlling global climate.
2. North Atlantic - directly affects the climate of Europe.

A major part of the UK effort was in the Southern Ocean and work included:

• Two surveys, in the South Atlantic as part of the WOCE Hydrographic Programme.
• SWINDEX, a year long study of the Antarctic Circumpolar Current (ACC) where it crosses major topography south of Africa.
• ADOX, a study of deep water flow from the Atlantic to the Indian Ocean.
• ACCLAIM, a study of the ACC by altimetry and island measurements.

In the North Atlantic the UK undertook:

• NATRE, a purposeful tracer experiment to look at cross isopycnic processes.
• CONVEX, a study of the deep ocean circulation and its changes.
• VIVALDI, a seven year programme of seasonally repeated surveys to study the upper ocean.
• Long-term observations of ocean climate in the North West Approaches.

Satellite ocean surface topography, temperature and wind data were merged with in situ observations and models to create a complete description of ocean circulation, eddy motion and the way the ocean is driven by the atmosphere.

The surveys were forerunners to the international Global Ocean Observing System (GOOS). GOOS was later established to monitor annual to decadal changes in ocean circulation and heat storage which are vital in the prediction of climate change.

Data Activity or Cruise Information

Data Activity

BODC Sample Metadata Report for DI233_CTD_CTD13547

Please note:the supplied parameters may not have been sampled from all the bottle firings described in the table above. Cross-match the Sample Reference Number above against the SAMPRFNM value in the data file to identify the relevant metadata.

Related Data Activity activities are detailed in Appendix 1

Cruise

Complete Cruise Metadata Report is available here

Fixed Station Information

No Fixed Station Information held for the Series

BODC Quality Control Flags

The following single character qualifying flags may be associated with one or more individual parameters with a data cycle:

SeaDataNet Quality Control Flags

The following single character qualifying flags may be associated with one or more individual parameters with a data cycle:

Appendix 1: DI233_CTD_CTD13547

Related series for this Data Activity are presented in the table below. Further information can be found by following the appropriate links.

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