Metadata Report for BODC Series Reference Number 1868270

• 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

Public domain data

These data have no specific confidentiality restrictions for users. However, users must acknowledge data sources as it is not ethical to publish data without proper attribution. Any publication or other output resulting from usage of the data should include an acknowledgment.

The recommended acknowledgment is

"This study uses data from the data source/organisation/programme, provided by the British Oceanographic Data Centre and funded by the funding body."

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.

Dissolved Oxygen for cruises Belgica BG9309, BG9322, BG9412, BG9506, BG9521 and BG9522

Document History

Converted from CDROM documentation.

Content of data series

Data Originator

Dr Michel Frankignoulle, University of Liege, Belgium.

Sampling strategy and methodology

Water samples taken from CTD rosette bottles were analysed using the classical Winkler technique using a Metrohm automatic titration system.

Comments on data quality

Cruise Belgica BG9506

The Winkler oxygen data from this cruise are exceptionally low with surface saturations of 90 per cent or less and values in the oxygen minimum below 180 µM. Compared to data from the same area at the same time of year (1993 and 1994), the data are systematically low by 10 per cent. The CTD data, prior to calibration against the bottle data, look as expected with surface saturations scattered around 100 per cent and values in the oxygen minimum of 190-200 µM.

The conclusion from examination of the data is that there is a systematic error in the bottle data from this cruise. Consequently, all bottle data have been flagged suspect and no bottle calibration has been applied to the CTD data.

Cruises Belgica BG9521 and BG9522

The CTD oxygen data from these cruises were detrimentally affected by temperature gradients in the water column and the oxygen sensor appeared slow to equilibrate. Empirical correction on a cast by cast basis was attempted for BG9521 but there were insufficient bottle data to do this for BG9522 and all shallow (above 200m) CTD oxygen data from this cruise have been jettisoned.

The shallow CTD derived values from BG9521 should be used with caution and wherever possible the Winkler data should be used instead. The deep CTD data from both cruises are of better quality. See the CTD data documents from these cruises for further details.

References

Aminot, A. and Chaussepied, M. (eds), 1983. Manuel des analyses chimiques en milieau marin. C.N. L'Exploitation des Oceans. 395 pp.

Benson, B.B., Krause D. (1984). The concentration and isotopic fractionation of oxygen dissolved in fresh water and sea water in equilibrium with the atmosphere. Limnol.Oceanogr., 29, 620-632.

Project Information

No Project Information held for the Series

Data Activity or Cruise Information

Data Activity

BODC Sample Metadata Report for BG9309_CTD_GC11

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: BG9309_CTD_GC11

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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