Metadata Report for BODC Series Reference Number 1691043

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 Naomi Greenwood
Originating Organization Centre for Environment, Fisheries and Aquaculture Science Lowestoft Laboratory
Processing Status banked
Project(s) Oceans 2025 Theme 10 SO11

Data Identifiers

Originator's Identifier PD21_10_CTD_PIGX_533:cast030
BODC Series Reference 1691043

Time Co-ordinates(UT)

Start Time (yyyy-mm-dd hh:mm) 2010-07-08 13:04
End Time (yyyy-mm-dd hh:mm) -
Nominal Cycle Interval -

Spatial Co-ordinates

Latitude 53.69943 N ( 53° 42.0' N )
Longitude 3.36475 W ( 3° 21.9' W )
Positional Uncertainty Unspecified
Minimum Sensor Depth 1.7 m
Maximum Sensor Depth 1.7 m
Minimum Sensor Height 21.0 m
Maximum Sensor Height 21.0 m
Sea Floor Depth 22.7 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

Centre for Environment, Fisheries and Aquaculture Science (Cefas) data access conditions

The Centre for Environment, Fisheries and Aquaculture Science (Cefas) is an Executive Agency of the Department of Environment, Food and Rural Affairs (Defra), formerly the Ministry of Agriculture, Fisheries and Food (MAFF). It was also known previously as the Directorate of Fisheries Research (DFR). This data policy refers to data collected by the organisation under all titles.

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.

RV Prince Madog cruise PD21_10 chlorophyll and phaeopigment series measured by Cefas

Originator's Data Processing

Samples for chlorophyll and phaeopigments were collected by the Centre for Environment, Fisheries and Aquaculture Science (Cefas) on a National Oceanography Centre, Liverpool (NOC) [previously the Proudman Oceanographic Laboratory] Oceans 2025 SO11 cruise (number 70) in Liverpool Bay. The cruise took place from 07 - 08 July 2010. Samples were collected near-surface from water bottle rosette sampling systems mounted on the lowered CTD during 13 casts. Triplicate samples were taken from cast001 and cast002 with single samples taken during all other casts.

For each sample, a 250 ml sample is passed through a Whatman GF/F filter under low vacuum. The filter paper is folded in half, loosely wrapped in aluminium foil and placed in a plastic bag. Samples are stored in this way in a box containing desiccant at -18 °C until analysis. Filters are extracted using 8 ml 90% acetone and measured fluorometrically according to Tett (1987) for chlorophyll-a and phaeopigments. Cefas use a Turner 10 AU field fluorometer, which has been calibrated using a pure solution of chlorophyll-a.

Processing Undertaken by BODC

The data were supplied to BODC as an Excel spreadsheet. This was converted to an ASCII format file for loading into the BODC archive. The variables supplied by the Data Originator were mapped to BODC parameter vocabularies as follows:

Originator's Parameter Units Description BODC Parameter Code Units Comments
CHL µg l -1 Concentration of chlorophyll-a {chl-a} per unit volume of the water body [particulate >GF/F phase] by filtration, acetone extraction and fluorometry CPHLFLP1 mg m -3 µg l -1 = mg m -3
- - 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 CLSDFLP1 mg m -3 Calculated by BODC
pheopigment µg l -1 Concentration of phaeopigments per unit volume of the water body [particulate >GF/F phase] by filtration, acetone extraction and fluorometry PHAEFLP1 mg m -3 µg l -1 = mg m -3
- - Concentration standard deviation of phaeopigments per unit volume of the water body [particulate >GF/F phase] by filtration, acetone extraction and fluorometry PHSDFLP1 mg m -3 Calculated by BODC

The data were loaded into the database by matching the sample's station identifier and depth with the information already held in the database for this cruise. The surface samples were sourced from rosette bottle 11 for each cast, with the exception of cast013 where the source of the sample was rosette bottle 12.

Triplicate samples were taken by CEFAS during cast001 and cast002. The mean and standard deviation of these samples were calculated by BODC and stored in the database. The individual sample values have been archived and are available on request.


Tett , P. 1987. Plankton. In: J.M. Baker, J.W. Wolff, eds., Biological surveys of estuaries and coasts. Cambridge University Press, Cambridge, pp 280-341.

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) 2010-07-08
End Date (yyyy-mm-dd) 2010-07-08
Organization Undertaking ActivityNational Oceanography Centre, Liverpool
Country of OrganizationUnited Kingdom
Originator's Data Activity IdentifierPD21_10_CTD_cast030
Platform Categorylowered unmanned submersible

BODC Sample Metadata Report for PD21_10_CTD_cast030

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
446083    5.00 3 1   19.00   19.10   18.40 Niskin bottle No problem reported    
446084    5.00 4 2   18.90   19.00   18.30 Niskin bottle No problem reported    
446085    5.00 8 3    5.90    7.00    5.90 Niskin bottle No problem reported    
446086    5.00 9 4    1.80    2.50    1.70 Niskin bottle No problem reported    
446087    5.00 10 5    2.10    2.30    1.70 Niskin bottle No problem reported    
446088    5.00 11 6    2.20    2.30    1.70 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 - 1676704 1309713


Cruise Name PD21/10
Departure Date 2010-07-07
Arrival Date 2010-07-08
Principal Scientist(s)Phil J Knight (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