Metadata Report for BODC Series Reference Number 1788546


Metadata Summary

Data Description

Data Category Water sample data
Instrument Type
NameCategories
Niskin bottle  discrete water samplers
Instrument Mounting lowered unmanned submersible
Originating Country United Kingdom
Originator Dr Carol Robinson
Originating Organization Plymouth Marine Laboratory
Processing Status banked
Project(s) Atlantic Meridional Transect Phase2(AMT)
 

Data Identifiers

Originator's Identifier AMT17_CTD_DOXY_57:CTD044s
BODC Series Reference 1788546
 

Time Co-ordinates(UT)

Start Time (yyyy-mm-dd hh:mm) 2005-11-16 05:01
End Time (yyyy-mm-dd hh:mm) -
Nominal Cycle Interval -
 

Spatial Co-ordinates

Latitude 21.12928 S ( 21° 7.8' S )
Longitude 22.43899 W ( 22° 26.3' W )
Positional Uncertainty 0.05 to 0.1 n.miles
Minimum Sensor Depth 1.8 m
Maximum Sensor Depth 300.3 m
Minimum Sensor Height 4698.5 m
Maximum Sensor Height 4997.0 m
Sea Floor Depth 4998.8 m
Sensor Distribution Unspecified -
Sensor Depth Datum Unspecified -
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)
DOXYWITX 1 Micromoles per litre WC_dissO2_Winkler Concentration of oxygen {O2 CAS 7782-44-7} per unit volume of the water body [dissolved plus reactive particulate phase] by Winkler titration
FIRSEQID 1 Dimensionless FireSeqNo Bottle firing sequence number
ROSPOSID 1 Dimensionless RosPos Bottle rosette position identifier
SAMPRFNM 1 Dimensionless SampRef Sample reference number
 

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 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 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.

Oxygen concentrations from CTD bottle samples collected during AMT17

Originator's Protocol for Data Acquisition and Analysis

These data originate from analyses on samples collected from 12 CTD rosette bottles from all CTD casts. Water samples were taken directly from the bottles in the Sea-Bird CTD rosette system using silicon tubing.

Dissolved oxygen concentrations were determined by automated Winkler titration with photometric end-point detection (Williamson and Jenkinson, 1982).

References Cited

Williams P.J.leB. and Jenkinson N.W., 1982. A transportable micro processor controlled precise Winkler titration suitable for field station and shipboard use. Limnology and Oceanography, 27, 576-584.

Instrumentation Description

Not applicable for this data set.

BODC Data Processing Procedures

Data were submitted via email in an Excel spreadsheet archived under BODC's accession number PML060007. Sample metadata (CTD cast, date, latitude, longitude, bottle number and depth) were checked against information held in the database. There were a number of small discrepancies. There were two CTD055 casts according to this worksheet, one with the steel and one with the titanium rig. The problem resulted from a mistyped CTD cast number, which was noted and corrected with CTD056t originally being referred to as CTD055t. Cast 55 was carried out on the steel rig and the depths and ROSPOS of the CTD055t cast match the CTD056t cast.

When comparing the data with measurements from the oxygen sensors on the CTD packages, it also became obvious that the depths provided in the originator's spreadsheet were suspect for some of the casts. Investigation was able to trace the problem back to a mix-up when attributing real depth to the data based on the Niskin bottle reference number. The depths were clearly assigned assuming the reference number was firing sequence while in fact it was rosette position. While for most casts these were identical, for a few casts this led to major errors in depth assignment. Once the depths were attributed based on rosette position rather than firing sequence the major outliers from the data calibration were no longer outliers. This provided the confidence that this was the correct way to assign the data. Decision was also corroborated against the hand-written bottle firing log sheets.

The temperature of fixation of the oxygen samples was also provided by the originators but not loaded to the database at the time of processing. These supplementary data are available on request.

The concentration data were provided in micromoles per litre. These units for the concentration data were consistent with the BODC parameter code units and no conversion was applied.

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

A parameter mapping table is provided below;

Originator's Parameter Units Description BODC Parameter Code Units Comments
O2 conc µmol l -1 Concentration of oxygen {O 2 } per unit volume of the water body [dissolved phase] by Winkler titration DOXYWITX µmol l -1 n/a

Data Quality Report

BODC was not advised of any specific quality issues with the data. The data were checked visually and used for the calibration of the CTD sensor. No values were flagged by BODC.

Problem Report

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:

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:

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

Start Date (yyyy-mm-dd) 2005-11-16
End Date (yyyy-mm-dd) 2005-11-16
Organization Undertaking ActivityPlymouth Marine Laboratory
Country of OrganizationUnited Kingdom
Originator's Data Activity IdentifierAMT17_CTD_CTD044s
Platform Categorylowered unmanned submersible

BODC Sample Metadata Report for AMT17_CTD_CTD044s

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
183857   20.00 1 1  303.00  303.20  300.30 Niskin bottle No problem reported    
183858   20.00 2 2  211.10  211.10  209.00 Niskin bottle No problem reported    
183859   20.00 3 3  210.80  211.10  208.80 Niskin bottle No problem reported    
183860   20.00 4 4  154.00  154.30  152.40 Niskin bottle No problem reported    
183861   20.00 5 5  146.20  146.50  144.70 Niskin bottle No problem reported    
183862   20.00 6 6  139.90  140.80  138.70 Niskin bottle No problem reported    
183863   20.00 7 7  139.60  140.60  138.50 Niskin bottle No problem reported    
183864   20.00 8 8  140.80  141.20  139.40 Niskin bottle No problem reported    
183865   20.00 9 9  140.00  140.30  138.50 Niskin bottle No problem reported    
183866   20.00 10 10  129.30  129.60  127.90 Niskin bottle No problem reported    
183867   20.00 11 11  116.40  116.70  115.10 Niskin bottle No problem reported    
183868   20.00 12 12   61.00   61.50   60.10 Niskin bottle No problem reported    
183869   20.00 13 13   61.20   61.50   60.20 Niskin bottle No problem reported    
183870   20.00 14 14   61.20   61.60   60.30 Niskin bottle No problem reported    
183871   20.00 15 15   33.60   33.80   32.80 Niskin bottle No problem reported    
183872   20.00 16 16   34.10   34.50   33.40 Niskin bottle No problem reported    
183873   20.00 17 17   33.80   34.20   33.10 Niskin bottle No problem reported    
183874   20.00 18 18   18.90   19.60   18.40 Niskin bottle No problem reported    
183875   20.00 19 19   18.60   19.10   18.00 Niskin bottle No problem reported    
183876   20.00 20 20   18.70   19.00   18.00 Niskin bottle No problem reported    
183877   20.00 21 21   18.60   18.70   17.80 Niskin bottle No problem reported    
183878   20.00 22 22    2.20    2.60    1.70 Niskin bottle No problem reported    
183879   20.00 23 23    2.10    2.40    1.50 Niskin bottle No problem reported    
183880   20.00 24 24    2.30    2.70    1.80 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 - 1127348 1631550

Cruise

Cruise Name D299 (AMT17)
Departure Date 2005-10-15
Arrival Date 2005-11-28
Principal Scientist(s)Patrick M Holligan (University of Southampton School of Ocean and Earth Science)
Ship RRS Discovery

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