Metadata Report for BODC Series Reference Number 1303926

• 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.

D230 Discrete CTD Inorganic Nutrient Sampling Document

Originator's Protocol for Data Acquisition and Analysis

Sample collection and analysis

Discrete dissolved inorganic nutrient samples were collected from Niskin bottles fired on 141 CTD casts performed during D230. Samples were collected in 30 ml plastic diluvial sample cups, each washed three times in the sample flow. Samples were stored in a fridge (up to a maximum of four hours duration) prior to onboard analysis. 8 ml subsamples were drawn into sample cups and run on the SOC Chemlab AAII-type Auto-Analyser connected to a digital-analysis microstream data capture and reduction system. Duplicates were analysed to ensure accuracy and to increase precision.

Primary standards were prepared in calibrated 500 ml glass volumetric flasks (calibrated polyethylene volumetric flasks for silicate), one standard solution for each nutrient being required for the cruise. These utilised pre-weighed salts measured prior to the cruise. Sets of working standards were typically made up from these on a daily basis in 100 ml calibrated polyethylene volumetric flasks, using artificial seawater (40 g/l NaCl). These were run in duplicate prior to each analytical run to enable sample calibration. Independent quality control samples were also prepared from standard solutions supplied by OSI and run (in duplicate) at intervals throughout the analysis.

The cruise report contains more in depth details of each nutrient analysis performed during the cruise.

BODC Data Processing Procedures

ASCII-formatted CTD sample data from this cruise were supplied to BODC during March 2001. The inorganic nutrient 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

Bacon, S., (1998). RRS Discovery Cruise 230, 07 AUG - 17 SEP 1997. FOUREX. Cruise Report No. 16 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 DI230_CTD_A25CTD034

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: DI230_CTD_A25CTD034

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

If you are interested in these series, please be aware we offer a multiple file download service. Should your credentials be insufficient for automatic download, the service also offers a referral to our Enquiries Officer who may be able to negotiate access.