Metadata Report for BODC Series Reference Number 1683111

Metadata Summary

Data Description

Data Category Water sample data
Instrument Type
Niskin bottle  discrete water samplers
Instrument Mounting lowered unmanned submersible
Originating Country United Kingdom
Originator Dr Andy Lane
Originating Organization National Oceanography Centre, Liverpool
Processing Status banked
Project(s) Oceans 2025 Theme 10 SO11

Data Identifiers

Originator's Identifier PD29_10_CTD_PIGX_177:cast015
BODC Series Reference 1683111

Time Co-ordinates(UT)

Start Time (yyyy-mm-dd hh:mm) 2010-08-11 21:39
End Time (yyyy-mm-dd hh:mm) -
Nominal Cycle Interval -

Spatial Co-ordinates

Latitude 53.69820 N ( 53° 41.9' N )
Longitude 3.22992 W ( 3° 13.8' W )
Positional Uncertainty Unspecified
Minimum Sensor Depth 2.0 m
Maximum Sensor Depth 16.6 m
Minimum Sensor Height 3.9 m
Maximum Sensor Height 18.5 m
Sea Floor Depth 20.5 m
Sensor Distribution Unspecified -
Sensor Depth Datum Unspecified -
Sea Floor Depth Datum Instantaneous - Depth measured below water line or instantaneous water body surface


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)
CPHLFLP1 1 Milligrams per cubic metre chl-a_water>GF/F_fluor Concentration of chlorophyll-a {chl-a CAS 479-61-8} per unit volume of the water body [particulate >GF/F phase] by filtration, acetone extraction and fluorometry
FIRSEQID 1 Dimensionless FireSeqNo Bottle firing sequence number
PHAEFLP1 1 Milligrams per cubic metre Fluor_Phae_>GFF Concentration of phaeopigments {pheopigments} per unit volume of the water body [particulate >GF/F phase] by filtration, acetone extraction and fluorometry
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.


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.

Discrete Chlorophyll a and Phaeopigment data measured by POL on Coastal Observatory cruise 71 (PD29_10)

Sampling Strategy

Discrete chlorophyll and phaeopigment samples were collected by the Proudman Oceanographic Laboratory (POL), Liverpool on Oceans 2025 SO11 cruise 71 (PD29_10) in Liverpool Bay. The cruise ran from 10 to 12 August 2010 on the RV Prince Madog.

Originators Processing

Pre-processing: The test tubes were cleaned, paired up with screw-caps, numbered and placed in racks.

Sample collection: The filters were Whatman 0.7 µm pore size 47 mm diameter GF/F filters (straight from the box). Tweezers were used to handle the filters at the edges. Clean buckets were placed beneath the Niskin bottles on the CTD frame and the entire contents were taken. The samples were stirred before being measured out, typically 500 ml was required, less if turbid conditions. The pre-weighed filter was placed on to the holder and the funnel assembled. The vacuum pump was switched on and the suction carefully set to <0.2 bar The samples were added in stages and the filter was not allowed to go dry. The filter was then placed in a test tube, the cap was put on and then the tube was wrapped in aluminium foil, labelled and returned to the freezer at -18°C.

Post-processing: A fluorometric method was used: a chlorophyll standard was made and used to calibrate the fluorometer (Turner Designs, USA). The test tubes were taken out of the freezer and 5 ml of cold 90 % acetone was added. The foil wrapped tubes were then put in a polypropylene beaker with water and sonicated in the water bath for 15 minutes. The samples were not allowed to warm up and exposure to high light levels was avoided. The filters were removed from the pigmented acetone and analysed by the fluorometer as soon as was possible. A drop of 10% hydrochloric acid was added to convert chlorophyll to phaeophytin and the sample was then analysed again.

BODC Processing

The data were supplied to BODC as an Excel spreadsheet. This was converted to an ASCII format file for loading into the BODC database. Methodology and units were checked against information held in the BODC parameter dictionary and an appropriate parameter code was attributed to each variable.

Originator's Variable Units BODC Parameter Code Definition of Parameter Code Units Comments
Chlorophyll -a concentration µg l -1 CPHLFLP1 Concentration of chlorophyll-a {chl-a} per unit volume of the water body [particulate >GF/F phase] by filtration, acetone extraction and fluorometry mg m -3 No conversion required as µg l -1 = mg m -3
    CLSDFLP1 Concentration standard deviation of chlorophyll-a {chl-a} per unit volume of the water body [particulate >GF/F phase] by filtration, acetone extraction and fluorometry mg m -3 Standard deviation values calculated by BODC
Concentration of phaeophytin-a µg l -1 PHAEFLP1 Concentration of phaeopigments per unit volume of the water body [particulate >GF/F phase] by filtration, acetone extraction and fluorometry. mg m -3 No conversion required as µg l -1 = mg m -3
    PHSDFLP1 Concentration standard deviation of phaeopigments per unit volume of the water body [particulate >GF/F phase] by filtration, acetone extraction and fluorometry. mg m -3 Standard deviation values calculated by BODC

The data and metadata fields were checked and then loaded into the database under the Oracle Relational Database Management System by matching the sample's station identifier and depth with the information already held in the database for this cruise. Where the data supplied included multiple replicates for each station, the mean value and standard deviation were loaded into the database. For single samples, the data were loaded without further modification. Data were then quality controlled by BODC and where suspect values were identified flags were applied.

Project Information

Oceans 2025 Theme 10, Sustained Observation Activity 11: Liverpool Bay and Irish Sea Coastal Observatory

Sustained, systematic observations of the ocean and continental shelf seas at appropriate time and space scales allied to numerical models are key to understanding and prediction. In shelf seas these observations address issues as fundamental as 'what is the capacity of shelf seas to absorb change?' encompassing the impacts of climate change, biological productivity and diversity, sustainable management, pollution and public health, safety at sea and extreme events. Advancing understanding of coastal processes to use and manage these resources better is challenging; important controlling processes occur over a broad range of spatial and temporal scales which cannot be simultaneously studied solely with satellite or ship-based platforms.

Considerable effort has been spent by the Proudman Oceangraphic Laboratory (POL) in the years 2001 - 2006 in setting up an integrated observational and now-cast modelling system in Liverpool Bay (see Figure), with the recent POL review stating the observatory was seen as a leader in its field and a unique 'selling' point of the laboratory. Cost benefit analysis (IACMST, 2004) shows that benefits really start to accrue after 10 years. In 2007 - 2012 exploitation of (i) the time series being acquired, (ii) the model-data synthesis and (iii) the increasingly available quantities of real-time data (e.g. river flows) can be carried out through Sustained Observation Activity (SO) 11, to provide an integrated assessment and short term forecasts of the coastal ocean state.

BODC image

Overall Aims and Purpose of SO 11

Measurement and Modelling Activities

More detailed information on this Work Package is available at pages 32 - 35 of the official Oceans 2025 Theme 10 document: Oceans 2025 Theme 10



IACMST., 2004. The Economics of Sustained Marine Measurements. IACMST Information Document, N0.11, Southampton: IACMST, 96 pp

Data Activity or Cruise Information

Data Activity

Start Date (yyyy-mm-dd) 2010-08-11
End Date (yyyy-mm-dd) 2010-08-11
Organization Undertaking ActivityNational Oceanography Centre, Liverpool
Country of OrganizationUnited Kingdom
Originator's Data Activity IdentifierPD29_10_CTD_cast015
Platform Categorylowered unmanned submersible

BODC Sample Metadata Report for PD29_10_CTD_cast015

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
445842    5.00 3 1   16.20   17.60   16.30 Niskin bottle No problem reported    
445843    5.00 4 2   17.10   17.40   16.60 Niskin bottle No problem reported    
445896    5.00 9 3    2.20    2.80    2.00 Niskin bottle No problem reported    
445897    5.00 10 4    2.30    3.00    2.20 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 - 1313202


Cruise Name PD29/10
Departure Date 2010-08-10
Arrival Date 2010-08-12
Principal Scientist(s)Jo Hopkins (National Oceanography Centre, Liverpool)
Ship RV Prince Madog

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