Metadata Report for BODC Series Reference Number 1787973

• 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.

Oxygen concentrations from CTD bottle samples collected during AMT15

Originator's Protocol for Data Acquisition and Analysis

This data originates from analyses on samples collected from 34 CTD casts. Water samples were taken directly from the bottles in the Sea-Bird CTD rosette system using silicon tubing.

Dissolved oxygen concentration was determined by automated Winkler titration with photometric end-point detection (Williamson and Jenkinson, 1982).

References Cited

Williams P.J.leB. and Jenkinson N.W., 1982. A transportable micro processor controlled precise Winkler titration suitable for field station and shipboard use. Limnology and Oceanography, 27, 576-584.

Instrumentation Description

Not applicable for this data set.

BODC Data Processing Procedures

Data were submitted via email in an Excel spreadsheet archived under BODC's accession number PML060015. The data were received in a spreadsheet containing CTD station number, Niskin bottle number, Depth, Oxygen bottle number, fixation temperature, in situ temperature and salinity. Sample metadata (CTD cast, bottle number and depth) were checked against information held in the database. There were a number of discrepancies:

• For a number of samples the bottle numbers did not match the depths of bottle firing from the SeaBird files and in these cases the data were loaded against the depth provided.
• The data provided for cast 1 had sample depths which matched cast 2 not cast 1 and were loaded to cast 2.
• Cast 18 bottle number 10 had depth 120 m provided. The SeaBird files indicate this bottle was fired at 86 m and the value provided was a more accurate fit for the oxygen sensor calibration at 86m bottle firing.
• Cast 25 bottle number 10 had no depth provided. The SeaBird files indicate this bottle was fired at 86 m.
• Cast 48 had data from an unidentified cast included. This was seperated out and compared against the bottle firing and depth pattern for titanium rig casts after cast 48. The data were loaded against cast 51 but flagged as the cast number was not confirmed.
• Cast 71 had data from an unidentified cast included. This was seperated out and compared against the bottle firing and depth pattern for stainless steel rig casts after cast 71. The data were loaded against cast 82 but flagged as the cast number was not confirmed.
• Cast 95 had a bottle number/depth combinations (6/125 m and 1/500m) that could not be matched to the SeaBird bottle firing depths (6/499 m and 1/1m). These data were loaded to the database based on the rosette bottle number and have been flagged as there appears to have been a mix up with the bottles.

The concentration data were provided in micromoles per litre. These units for the concentration data were consistent with the BODC parameter code units and no conversion was applied.

The data were reformatted and loaded in BODC's samples database under Oracle Relational Database Management System. Data were marked up with BODC parameter codes and loaded into the database. Individual samples were matched through rosette sampling bottle and depth.

A parameter mapping table is provided below;

Data Quality Report

BODC was not advised of any specific quality issues with the data. The data were checked visually and used for the calibration of the CTD sensor. Where there were questions over the metadata flags have been added.

Problem Report

Not relevant to this data set.

Project Information

The Atlantic Meridional Transect - Phase 2 (2002-2006)

Who was involved in the project?

The Atlantic Meridional Transect Phase 2 was designed by and implemented by a number of UK research centres and universities. The programme was hosted by Plymouth Marine Laboratory in collaboration with the National Oceanography Centre, Southampton. The universities involved were:

• University of Liverpool
• University of Newcastle
• University of Plymouth
• University of Southampton
• University of East Anglia

What was the project about?

AMT began in 1995, with scientific aims to assess mesoscale to basin scale phytoplankton processes, the functional interpretation of bio-optical signatures and the seasonal, regional and latitudinal variations in mesozooplankton dynamics. In 2002, when the programme restarted, the scientific aims were broadened to address a suite of cross-disciplinary questions concerning ocean plankton ecology and biogeochemistry and the links to atmospheric processes.

The objectives included the determination of:

• how the structure, functional properties and trophic status of the major planktonic ecosystems vary in space and time
• how physical processes control the rates of nutrient supply to the planktonic ecosystem
• how atmosphere-ocean exchange and photo-degradation influence the formation and fate of organic matter

The data were collected with the aim of being distributed for use in the development of models to describe the interactions between the global climate system and ocean biogeochemistry.

When was the project active?

The second phase of funding allowed the project to continue for the period 2002 to 2006 and consisted of six research cruises. The first phase of the AMT programme ran from 1995 to 2000.

Brief summary of the project fieldwork/data

The fieldwork on the first three cruises was carried out along transects from the UK to the Falkland Islands in September and from the Falkland Islands to the UK in April. The last three cruises followed a cruise track between the UK and South Africa, only deviating from the traditional transect in the southern hemisphere. During this phase the research cruises sampled further into the centre of the North and South Atlantic Ocean and also along the north-west coast of Africa where upwelled nutrient rich water is known to provide a significant source of climatically important gases.

Who funded the project?

Natural Environment Research Council (NERC)

Data Activity or Cruise Information

Data Activity

BODC Sample Metadata Report for AMT15_CTD_CTD048t

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: AMT15_CTD_CTD048t

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.