Metadata Report for BODC Series Reference Number 1093381


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 AMT1_CTD_CTD18_Woodward_nuts
BODC Series Reference 1093381
 

Time Co-ordinates(UT)

Start Time (yyyy-mm-dd hh:mm) 1995-10-13 15:38
End Time (yyyy-mm-dd hh:mm) -
Nominal Cycle Interval -
 

Spatial Co-ordinates

Latitude 19.64470 S ( 19° 38.7' S )
Longitude 35.36176 W ( 35° 21.7' W )
Positional Uncertainty 0.0 to 0.01 n.miles
Minimum Sensor Depth 6.8 m
Maximum Sensor Depth 200.4 m
Minimum Sensor Height 3817.3 m
Maximum Sensor Height 4010.9 m
Sea Floor Depth 4017.7 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 Instantaneous - Depth measured below water line or instantaneous water body surface
 

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)
NTRIAATX 1 Micromoles per litre NO2_Unfilt_ColAA Concentration of nitrite {NO2- CAS 14797-65-0} per unit volume of the water body [dissolved plus reactive particulate phase] by colorimetric autoanalysis
NTRZAATX 1 Micromoles per litre NO3+NO2_Unfilt_ColAA Concentration of nitrate+nitrite {NO3+NO2} per unit volume of the water body [dissolved plus reactive particulate phase] by colorimetric autoanalysis
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.

AMT1 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 25 CTD casts.

The samples were taken from vertical profiles at each station. They were stored in the dark at less than 4°C in a laboratory refrigerator and were analysed as a batch shortly after the CTD samples were obtained. Thus, the vertical profile samples were usually analysed within one hour of collection.

Nutrients were analysed using a four-channel segmented-flow auto-analyser. The determinations were made using a Technicon Autoanalyser II 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.

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

Technicon Autoanalyser II

BODC Data Processing Procedures

Data were submitted to BODC in Microsoft Excel spreadsheet format. Sample metadata were checked against information held in the database. Originator's sample ID was matched based on latitude/longitude and bottle firing depth. Originator file provided latitude labelled as longitude and longitude labelled as latitude. Station/Sample reference provided is the Julian day that sampling took place on. These were matched to the CTD casts that took place at midday (ship's time) each day on the cruise.

There was no phosphate data for 1 sample (CTD24/Sample 296 at depth 40m) - indicated by ND in originator's file. There was a replicate measurement provided at 140 m on CTD16 (Station/Sample 284). The mean of these 2 measurements for each parameter was entered into the database for the bottle sampled at this depth.

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) 1995-10-13
End Date (yyyy-mm-dd) 1995-10-13
Organization Undertaking ActivityPlymouth Marine Laboratory
Country of OrganizationUnited Kingdom
Originator's Data Activity IdentifierAMT1_CTD_CTD18
Platform Categorylowered unmanned submersible

BODC Sample Metadata Report for AMT1_CTD_CTD18

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
501570   10.00      203.90  204.80  200.40 Niskin bottle No problem reported    
501571   10.00      181.90  183.00  178.60 Niskin bottle No problem reported    
501572   10.00      162.60  163.40  159.30 Niskin bottle No problem reported    
501573   10.00      141.90  142.90  138.90 Niskin bottle No problem reported    
501574   10.00      122.00  122.70  118.90 Niskin bottle No problem reported    
501575   10.00       68.10   68.60   65.30 Niskin bottle No problem reported    
501576   10.00       61.80   62.60   59.20 Niskin bottle No problem reported    
501577   10.00       13.30   13.90   10.90 Niskin bottle No problem reported    
501578   10.00       11.60   12.10    9.10 Niskin bottle No problem reported    
501579   10.00        9.20    9.80    6.80 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.

Other Series linked to this Data Activity - 1632239

Cruise

Cruise Name JR19950921 (AMT1, JRXX1)
Departure Date 1995-09-21
Arrival Date 1995-10-24
Principal Scientist(s)David Robins (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