Metadata Report for BODC Series Reference Number 2105234

• 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.

AMT20 (JC053) dissolved oxygen concentrations from CTD bottle samples

Originator's Protocol for Data Acquisition and Analysis

This data originates from analyses on samples collected from 64 CTD casts during the cruise. Samples were taken from between 3 to 7 bottles fired during the cast and samples were collected from one cast of each of the two rigs (stainless and titanium) used every day. This ensured there were data for the calibration of the oxygen sensor on each rig throughout the cruise.

Dissolved oxygen concentration was determined by whole-bottle Winkler titration to a photometric endpoint. A thiosulpohate solution of approx. 0.1770 mol L^-1 was used, standardised with a KIO₃ solution of 0.1N (prepared gravimetrically at UEA and shipped as a solution). Blanks were determined in MQ water (Dickson, 1996).

References Cited

Dickson A.G., 1996. Determination of dissolved oxygen in seawater by Winkler titration, in WOCE Operations Manual. Volume 3: The Observational Programme. Section 3.1: WOCE Hydrographic Programme. Part 3.1.3: WHP Operations and Methods, edited by World Ocean Circulation Experiment, Woods Hole, Massachussetts, USA.

Instrumentation Description

Not applicable for this data set.

BODC Data Processing Procedures

Data were submitted via email in an Excel spreadsheet after the cruise and archived under BODC's accession number UEA110074. Sample metadata (CTD cast, date, bottle number and depth) were checked against information held in the database. There was one minor depth discrepancy, CTD88s rosette bottle 5 was provided with depth 64.9m where the actual bottle firing depth recorded in the SeaBird bottle file for this bottle was 74.9m. Data was loaded with depth 74.9m. The samples from two casts (CTD04s and CTD16s) were provided without rosette bottle numbers or sample depths, therefore these data were not loaded to the database.

The oxygen concentration data were provided in micromoles per litre and no unit conversions were applied. There were 18 samples with replicate data and 17 of these samples had the average and standard deviation of the replicate values calculated for loading into the database. One sample (CTD38t, rosette bottle 21, depth 1.3m) was supplied with one of the replicates flagged suspect, in this case the replicates were not averaged and the unflagged data was loaded.

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 before being loaded into the database. Individual samples were matched through rosette sampling bottle and depth.

A parameter mapping table is provided below;

Data Quality Report

There were 11 data points flagged as suspect by the data originator. One of these suspect data points was not loaded (CTD38t, rosette bottle 21, depth 1.3m, oxy concⁿ = 189.32 µmol l^-1)as there was a replicate measurement from the same sample that was considered to be of good quality. The 10 suspect data points loaded to the database have been flagged accordingly. No further values were flagged by BODC.

Problem Report

Not relevant to this data set.

Project Information

Oceans 2025 Theme 10, Sustained Observation Activity 1: The Atlantic Meridional Transect (AMT)

The Atlantic Meridional Transect has been operational since 1995 and through the Oceans 2025 programme secures funding for a further five cruises during the period 2007-2012. The AMT programme began in 1995 utilising the passage of the RRS James Clark Ross between the UK and the Falkland Islands southwards in September and northwards in April each year. Prior to Oceans 2025 the AMT programme has completed 18 cruises following this transect in the Atlantic Ocean. This sustained observing system aims to provide basin-scale understanding of the distribution of planktonic communities, their nutrient turnover and biogenic export in the context of hydrographic and biogeochemical provinces of the North and South Atlantic Oceans.

The Atlantic Meridional Transect Programme is an open ocean in situ observing system that will:

• give early warning of any fundamental change in Atlantic ecosystem functionng
• improve forecasts of the future ocean state and associated socio-economic impacts
• provide a "contextual" logistical and scientific infrastructure for independently-funded national and international open ocean biogeochemical and ecological research.

The specific objectives are:

• To collect hydrographic, chemical, ecological and optical data on transects between the UK and the Falkland Islands
• To quantify the nature and causes of ecological and biogeochemical variability in planktonic ecosystems
• To assess the effects of variability in planktonic ecosystems on biogenic export and on air-sea exchange of radiatively active gases

The measurements taken and experiments carried out on the AMT cruises will be closely linked to Themes 2 and 5. The planned cruise track also allows for the AMT data to be used in providing spatial context to the Sustained Observation Activities at the Porcupine Abyssal Plain Ocean Observatory (SO2) and the Western Channel Observatory (SO10).

More detailed information on this Work Package is available at pages 6 - 9 of the official Oceans 2025 Theme 10 document: Oceans 2025 Theme 10

Weblink: http://www.oceans2025.org/

Data Activity or Cruise Information

Data Activity

BODC Sample Metadata Report for JC053_CTD_CTD77s

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: JC053_CTD_CTD77s

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.