Metadata Report for BODC Series Reference Number 1094913


Metadata Summary

Data Description

Data Category Water sample data
Instrument Type
NameCategories
Technicon AutoAnalyzer II colorimetric autoanalyser  colorimeters; autoanalysers
Niskin bottle  discrete water samplers
Instrument Mounting research vessel
Originating Country United Kingdom
Originator Mr Malcolm Woodward
Originating Organization Plymouth Marine Laboratory
Processing Status banked
Project(s) Atlantic Meridional Transect (AMT)
 

Data Identifiers

Originator's Identifier AMT10_CTD_AMT10-20_Woodward_nuts
BODC Series Reference 1094913
 

Time Co-ordinates(UT)

Start Time (yyyy-mm-dd hh:mm) 2000-04-23 11:37
End Time (yyyy-mm-dd hh:mm) -
Nominal Cycle Interval -
 

Spatial Co-ordinates

Latitude 1.94233 N ( 1° 56.5' N )
Longitude 25.26049 W ( 25° 15.6' W )
Positional Uncertainty 0.0 to 0.01 n.miles
Minimum Sensor Depth 10.2 m
Maximum Sensor Depth 200.5 m
Minimum Sensor Height 3778.25 m
Maximum Sensor Height 3968.55 m
Sea Floor Depth 3978.75 m
Sensor Distribution Variable common depth - All sensors are grouped effectively at the same depth, but this depth varies significantly during the series
Sensor Depth Datum Instantaneous - Depth measured below water line or instantaneous water body surface
Sea Floor Depth Datum Chart reference - Depth extracted from available chart
 

Parameters

BODC CODE Rank Units Short Title Title
ADEPZZ01 1 Metres DepBelowSurf Depth below surface of the water body
BOTTFLAG 1 Dimensionless C22_flag Sampling process quality flag (BODC C22)
PHOSAATX 1 Micromoles per litre PO4_Unfilt_ColAA Concentration of phosphate {PO43- CAS 14265-44-2} per unit volume of the water body [dissolved plus reactive particulate phase] by colorimetric autoanalysis
SAMPRFNM 1 Dimensionless SampRef Sample reference number
SLCAAATX 1 Micromoles per litre SiOx_Unfilt_ColAA Concentration of silicate {SiO44- CAS 17181-37-2} per unit volume of the water body [dissolved plus reactive particulate phase] by colorimetric autoanalysis
 

Definition of Rank

  • Rank 1 is a one-dimensional parameter
  • Rank 2 is a two-dimensional parameter
  • Rank 0 is a one-dimensional parameter describing the second dimension of a two-dimensional parameter (e.g. bin depths for moored ADCP data)

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

Frequency 420 kHz
Beam width 1.8° at -3 dB
Pulse lenght 0.1 m
Acoustic range precision ± 2.5 cm
Sampling rate 1 Hz
Tilt accuracy ± 0.5°
Tilt resolution ± 0.01°

Diameter of ensonified area
(dependent on acoustic range)

0.9 m for 30 m range

3.1 m for 100 m range

6.3 m for 200 m range

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 have a capacity between 1.7 and 30 L, while Lever Action bottles have a capacity between 1.7 and 12 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;

Originator's Parameter Units Description BODC Parameter Code Units Comments
Nitrate+Nitrite µmol l -1 Concentration of nitrate+nitrite {NO 3 +NO 2 } per unit volume of the water body [dissolved plus reactive particulate phase] by colorimetric autoanalysis NTRZAATX µmol l -1 -
Nitrite µmol l -1 Concentration of nitrite {NO 2 } per unit volume of the water body [dissolved plus reactive particulate phase] by colorimetric autoanalysis NTRIAATX µmol l -1 -
Phosphate µmol l -1 Concentration of phosphate {PO 4 } per unit volume of the water body [dissolved plus reactive particulate phase] by colorimetric autoanalysis PHOSAATX µmol l -1 -
Silicate µmol l -1 Concentration of silicate {SiO 4 } per unit volume of the water body [dissolved plus reactive particulate phase] by colorimetric autoanalysis SLCAAATX µmol l -1 -

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:

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

Start Date (yyyy-mm-dd) 2000-04-23
End Date (yyyy-mm-dd) 2000-04-23
Organization Undertaking ActivityPlymouth Marine Laboratory
Country of OrganizationUnited Kingdom
Originator's Data Activity IdentifierAMT10_CTD_AMT10-20
Platform Categorylowered unmanned submersible

BODC Sample Metadata Report for AMT10_CTD_AMT10-20

Sample reference number Nominal collection volume(l) Bottle rosette position Bottle firing sequence number Minimum pressure sampled (dbar) Maximum pressure sampled (dbar) Depth of sampling point (m) Bottle type Sample quality flag Bottle reference Comments
506455          9.50    9.90   10.20 Niskin bottle No problem reported    
506695        200.70  201.70  200.50 Niskin bottle No problem reported    
506696        152.90  153.50  152.80 Niskin bottle No problem reported    
506697        112.20  112.50  112.20 Niskin bottle No problem reported    
506698         80.90   81.90   81.50 Niskin bottle No problem reported    
506699         72.30   73.50   73.00 Niskin bottle No problem reported    
506700         62.40   62.80   62.80 Niskin bottle No problem reported    
506701         57.20   57.50   57.60 Niskin bottle No problem reported    
506702         46.40   47.40   47.20 Niskin bottle No problem reported    
506703         26.50   26.90   27.10 Niskin bottle No problem reported    
506704         17.40   18.30   18.30 Niskin bottle No problem reported    

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.

Cruise

Cruise Name JR20000412 (AMT10, JR49)
Departure Date 2000-04-12
Arrival Date 2000-05-08
Principal Scientist(s)Chris Gallienne (Plymouth Marine Laboratory)
Ship RRS James Clark Ross

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:

Flag Description
Blank Unqualified
< Below detection limit
> In excess of quoted value
A Taxonomic flag for affinis (aff.)
B Beginning of CTD Down/Up Cast
C Taxonomic flag for confer (cf.)
D Thermometric depth
E End of CTD Down/Up Cast
G Non-taxonomic biological characteristic uncertainty
H Extrapolated value
I Taxonomic flag for single species (sp.)
K Improbable value - unknown quality control source
L Improbable value - originator's quality control
M Improbable value - BODC quality control
N Null value
O Improbable value - user quality control
P Trace/calm
Q Indeterminate
R Replacement value
S Estimated value
T Interpolated value
U Uncalibrated
W Control value
X Excessive difference

SeaDataNet Quality Control Flags

The following single character qualifying flags may be associated with one or more individual parameters with a data cycle:

Flag Description
0 no quality control
1 good value
2 probably good value
3 probably bad value
4 bad value
5 changed value
6 value below detection
7 value in excess
8 interpolated value
9 missing value
A value phenomenon uncertain