Metadata Report for BODC Series Reference Number 1095050

• 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 Quality Report - see processing documentation

Data quality information is included in the general documentation for this series. Please read.

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

Technicon AutoAnalyzer II (AAII)

The AAII is a segmented flow analyzer used for automated colorimetric analysis. The apparatus uses 2 mm diameter glass tubing and pumps reagents at flow rates of 2 to 3 ml s^-1, producing results at a typical rate of 30 to 60 samples per hour. The system comprises an autosampler, peristaltic pump, chemistry manifold a detector and a data acquisition software.

This instrument was replaced by the AA3 in 1997 which was upgraded to the AA3 HR systems in 2006.

Specifications

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.

AMT10 Nutrient (micromolar) measurements from CTD bottle samples

Originator's Protocol for Data Acquisition and Analysis

This data originates from analyses of bottle samples taken from 20 CTD casts.

Macro-nutrient analysis was carried out using air-segmented-flow, colorimetric techniques, with a Technicon Autoanalyser II. Samples for nutrient analysis were collected in 60 ml HDPE (Nalgene) bottles and analysed as soon as possible, but no later than three hours after collection.

Nutrients were analysed using a four-channel Technicon segmented-flow auto-analyser. The determinations were made using a Tehnicon AAII Autoanalyser running conventional chemistries: phosphate and silicate as described by Kirkwood (1989) and nitrate and nitrite using a modified version of Grasshoff's method as described by Brewer and Riley (1965). The nitrate was determined as nitrite using a copper-cadmium reduction column to reduce nitrate to nitrite and is, therefore, measured as nitrate plus nitrite. All results are presented as mmol m^-3 (µmol l^-1) of the elements nitrogen, phosphorus and silicon.

References Cited

Brewer, P.G. and J.P. Riley (1965) The automatic determination of nitrate in sea water. Deep-Sea Res., 12, 765-772.

Kirkwood, D.S. (1989) Simultaneous determination of selected nutrients in seawater. ICES CM1989/C:29, 12pp.

Instrumentation Description

Not relevant to this data set.

BODC Data Processing Procedures

Data were submitted to BODC in Microsoft Excel spreadsheet format and saved to the BODC archive with referebce PML030076. Sample metadata were checked against information held in the database. Originator's sample ID was matched based on latitude/longitude and bottle firing depth. These were matched to the CTD casts that took place at midday (ship's time) each day on the cruise.

Originator's id was matched in on latitude and bottle firing pattern. A discrepancy was found in the data for the date of latitude 27.533N. The date at this latitude in the data was 01/05/00 but all latitudes on this date were greater than 36.0N. It was assumed that the date is an error in the data. The date was changed to 29/04/00 for cast AMT10-28, which fit well with the bottle firing pattern and the sequence of positions sampled.

The data contained some replicate samples (i.e. multiple samples at a single depth). These were averaged so that only one bottle id is allocated to each depth. There was one sample depth (49.6 m) from the first CTD cast (AMT10-01) with replicate values, where one of the silicate readings is below the detection level (< 0.08 µmol l^-1) and once above (0.15 µmol l^-1). This is problematic to average and so the reading that was above the detection limit has been entered into the database.

Parameter codes defined in BODC parameter dictionary were assigned to the variables. The data were assigned parameter codes defined in BODC parameter dictionary. Data loaded into BODC's database using established BODC data banking procedures.

A parameter mapping table is provided below;

Data Quality Report

The dataset has been checked by the data originator - any suspect data values were removed from the data set before submission to BODC. The data originator highlighted samples with concentrations below the specified detection limits and these are flagged in the database with a flag of "<".

Problem Report

Not relevant to this data set.

Project Information

The Atlantic Meridional Transect (AMT) - Phase 1 (1995-2000)

Who was involved in the project?

The Atlantic Meridional Transect (AMT) programme was designed by and implemented as a collaboration between Plymouth Marine Laboratory (PML) and Southampton Oceanography Centre (SOC). The programme was hosted by Plymouth Marine Laboratory and involved additional researchers from UK and international universities throughout its duration.

What was the project about?

When AMT began in 1995 the programme provided a platform for international scientific collaboration, including the calibration and validation of SeaWiFs measurements and products. The programme provided an exceptional opportunity for nationally and internationally driven collaborative research and provided a platform for excellent multi-disciplinary oceanographic research. As an in situ observation system, the data collected by the AMT consortium informed on changes in biodiversity and function of the Atlantic ecosystem during this period of rapid change to our climate and biosphere.

The scientific aims were to assess:

• mesoscale to basin scale phytoplankton processes
• the functional interpretation of bio-optical signatures
• the seasonal, regional and latitudinal variations in mesozooplankton dynamics

When was the project active?

The first phase of the AMT programme ran from 1995 to 2000 and consisted of a total of 12 cruises. A second phase of funding allowed the project to continue for the period 2002 to 2006 with a further 6 cruises.

Brief summary of the project fieldwork/data

The AMT programme undertook biological, chemical and physical oceanographic research during the annual return passage of the RRS James Clark Ross between the UK and the Falkland Islands or the RRS Discovery between the UK and Cape Town, a distance of up to 13,500 km. This transect crossed a range of ecosystems from sub-polar to tropical and from euphotic shelf seas and upwelling systems to oligotrophic mid-ocean gyres. The transect route was covered north-south in September/October and south-north in April/May of each year.

The measurements of hydrographic and bio-optical properties, plankton community structure and primary production completed on the first 12 transects (1995-2000) represent the most coherent set of repeated biogeochemical observations over ocean basin scales. This unique dataset has led to several important discoveries concerning the identification of oceanic provinces, validation of ocean colour algorithms, distributions of picoplankton, identifying new regional sinks of pCO2 and variability in rates of primary production and respiration.

Who funded the project?

The programme was funded by the Natural Environment Research Council (NERC) and further support was received from the National Aeronautics and Space Administration (NASA) with equipment and funding from the Sea-viewing Wild Field-of-view Sensor (SeaWiFS) project.

Data Activity or Cruise Information

Data Activity

BODC Sample Metadata Report for AMT10_CTD_AMT10-38

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: AMT10_CTD_AMT10-38

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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