Metadata Report for BODC Series Reference Number 1873597

• 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.

AMT15 pigment composition (HPLC)

Data Acquisition and Analysis

Samples from the five main light depths were collected from 35 casts during the cruise. Samples were taken from niskin bottles fired during the early morning cast and filtered through GF/F filters. The filters were then frozen until the samples were returned to the lab in the UK at the end of the cruise. HPLC analysis was carried out after Barlow et al. (1997).

References Cited

Barlow R.G. , Cummings D.G. and Gibb S.W., 1997. Improved resolution of mono- and divinyl chlorophylls a and b and zeaxanthin and lutein in phytoplankton extracts using reverse phase C8 HPLC. Marine Ecology Progress Series, 161 , 303-307.

Instrumentation Description

Section not relevant.

BODC Data Processing Procedures

Data were submitted to BODC in Microsoft Excel spreadsheet format and archived in accession SOC090128. The file was provided to BODC with cast number, date, sampling position (LAT and LON) and depth as metadata.

Sample metadata were checked against information held in the database - there were three discrepancies. In the data file the LAT figures had the decimal point in the wrong place. Also a number of samples were identified with two cast numbers in the file, these corresponded to stations where two casts were taken to collect water. The samples were matched to the cast where the range of depths provided in the file matched the depths sampled. Finally for cast 41 the range of depths sampled matched the bottle firing depths for cast 42, both these casts were carried out pre-dawn at the same station and so the data were linked to cast 42.

Parameter codes defined in BODC parameter dictionary were assigned to the variables as shown in the table below. Two additional parameters in the file were not loaded to the database: "Fluor Chl" had been supplied to BODC previously and already been loaded, the data were included by the data originator as part of the QC process; "Tot Chl a" was derived as the sum of "Divinyl chl a" and "Chl a" and so was not uploaded to the database. The data were provided in units that were consistent with those used for the relevant parameters in the BODC database, with the exception of "Chl a" where a unit conversion was applied from ng l^-1 to mg m^-3.

Data loaded into BODC's database without any changes.

Data Quality Report

The data originator has carried out a QC analysis of the data by comparing the extracted chl-a fluorometry profiles with the pigment profiles generated from the HPLC analysis. BODC were not advised by the data originator of any suspect data points.

Problem Report

This section is 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_CTD013t

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_CTD013t

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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