Metadata Report for BODC Series Reference Number 1207465

Metadata Summary

Data Description

Data Category Hydrography nonvertical profile
Instrument Type
Trace Analytical RGA3 reduction gas analyser  gas chromatographs
Instrument Mounting research vessel
Originating Country Canada
Originator Dr Bob Moore
Originating Organization Dalhousie University Department of Oceanography
Processing Status banked
Online delivery of data Download available - Ocean Data View (ODV) format
Project(s) Oceans 2025 Theme 10 SO1:AMT

Data Identifiers

Originator's Identifier AMT20_UNDERWAYH2DATA_NO
BODC Series Reference 1207465

Time Co-ordinates(UT)

Start Time (yyyy-mm-dd hh:mm) 2010-10-14 10:17
End Time (yyyy-mm-dd hh:mm) 2010-11-22 17:59
Nominal Cycle Interval 240.0 seconds

Spatial Co-ordinates

Start Latitude 49.33591 N ( 49° 20.2' N )
End Latitude 47.77786 S ( 47° 46.7' S )
Start Longitude 12.17545 W ( 12° 10.5' W )
End Longitude 55.44222 W ( 55° 26.5' W )
Positional Uncertainty 0.0 to 0.01 n.miles
Minimum Sensor or Sampling Depth 0.7 m
Maximum Sensor or Sampling Depth 0.7 m
Minimum Sensor or Sampling Height -
Maximum Sensor or Sampling Height -
Sea Floor Depth -
Sea Floor Depth Source -
Sensor or Sampling Distribution Fixed common depth - All sensors are grouped effectively at the same depth which is effectively fixed for the duration of the series
Sensor or Sampling Depth Datum Approximate - Depth is only approximate
Sea Floor Depth Datum -


BODC CODERankUnitsTitle
AADYAA011DaysDate (time from 00:00 01/01/1760 to 00:00 UT on day)
AAFDZZ011DaysTime (time between 00:00 UT and timestamp)
ACYCAA011DimensionlessSequence number
ALATZZ011DegreesLatitude north
ALONZZ011DegreesLongitude east
MXRH2MSX1Nanomoles per litreMixing ratio (equilibrated marine sample) of hydrogen

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

AMT20 (JC053) Continuous Underway Dissolved Hydrogen Data Quality Document

A few isolated spikes occur throughought the data with more noise towards the end of the cruise.

A few longitudes were flagged as null data ('N') during the transfer where no longitude existed in the original submission.

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

Trace Analytical RGA3 reduction gas analyser

A mercuric oxide reduction gas analyser which detects H2 and CO. Methodology is gas chromatography followed by the reduction of mercuric oxide. Mercury vapour from this reaction is detected by UV absorption. Trace Analytical Inc. was acquired by Ametek Process Instruments in 2004. The instrument is no longer manufactured.

AMT20 (JC053) Continuous Underway Dissolved Hydrogen Instrumentation

Instrument Description

The underway system used to continuously measure the dissolved hydrogen concentration was based on the equilibrator described in Xie et al., 2001. The actual measurement was completed by a Reduced Gas Analyser (RGA3), Trace Analytical Inc.

Instrument Serial Number Paramater Measured BODC Parameter
Mercuric Oxide Reduction Gas CO Analyser RGA3 (Trace Analytical, Inc.). N/A Dissolved Hydrogen (H2) MXRH2MSX


Xie, H., Zafiriou, O. C., Wang, W. and Taylor, C. D. 2001. A simple automated continuous-flow-equilibration method for measuring carbon monoxide in seawater. Environmental Science and Technology. 35, 1475-1480.

AMT20 (JC053) Dissolved Hydrogen Concentration - Continuous Measurement from Surface Waters

Data Acquisition and Analysis

A new method of equilibrating seawater samples for Hydrogen measurement was employed for the AMT20 cruise allowing H2 to be measured from underway samples every 3.5 minutes. Underway samples were pumped from a depth of around 7 m, through the ship's non-toxic system, at a continuous flow rate of 1 L min-1 to a reservoir. A sample of this was then pumped to the equilibrator at approximately 14 mL min-1. An air segmented, continuous flow equilibrator similar to that developed by Xie et al. (2001) was used to obtain a gaseous sample from the seawater. Hydrogen measurements of the gaseous sample were made with a gas chroatograph that incorporated a reducing compound photometer. For each measurement, a chromatograph was generated from which a peak was produced. The peak from the chromatograph was compared to the peak from a reference gas it was then possible to calculate. The Hydrogen concentration of the sample was calculated by comparing chromotograph peaks from samples to peaks from known referencegas standards.

BODC Data Processing

Data were submitted to BODC as an Excel .xlsx file, containing the data and metadata, alongside a word document, containing the methodology. The data were then saved as two .csv files, one containing the data and the other containing the metadata. The data were then transferred to the BODC format and loaded to the database.

Parameter codes defined in the BODC parameter dictionary were assigned to the variable as shown in the table below:

Originator's Parameter Originator's Code BODC Parameter Code BODC Units Description
Latitude degrees +veN ALATZZ01 Degrees Latitude north
Longtiude degrees +veE ALONZZ01 Degrees Longitude east
H2 nmol/L MXRH2MSX nmol/L Mixing ratio (equilibrated marine sample) of hydrogen


Data were screened using in-house software, using the BODC flagging system. A few spikes were flagged as suspect ('M').


Xie, H., Zafiriou, O. C., Wang, W. and Taylor, C. D. 2001. A simple automated continuous-flow-equilibration method for measuring carbon monoxide in seawater. Environmental Science and Technology. 35, 1475-1480.

Project Information

Oceans 2025 Theme 10, Sustained Observation Activity 1: The Atlantic Meridional Transect (AMT)

The Atlantic Meridional Transect has been operational since 1995 and through the Oceans 2025 programme secures funding for a further five cruises during the period 2007-2012. The AMT programme began in 1995 utilising the passage of the RRS James Clark Ross between the UK and the Falkland Islands southwards in September and northwards in April each year. Prior to Oceans 2025 the AMT programme has completed 18 cruises following this transect in the Atlantic Ocean. This sustained observing system aims to provide basin-scale understanding of the distribution of planktonic communities, their nutrient turnover and biogenic export in the context of hydrographic and biogeochemical provinces of the North and South Atlantic Oceans.

The Atlantic Meridional Transect Programme is an open ocean in situ observing system that will:

The specific objectives are:

The measurements taken and experiments carried out on the AMT cruises will be closely linked to Themes 2 and 5. The planned cruise track also allows for the AMT data to be used in providing spatial context to the Sustained Observation Activities at the Porcupine Abyssal Plain Ocean Observatory (SO2) and the Western Channel Observatory (SO10).

More detailed information on this Work Package is available at pages 6 - 9 of the official Oceans 2025 Theme 10 document: Oceans 2025 Theme 10


Data Activity or Cruise Information


Cruise Name JC053 (AMT20)
Departure Date 2010-10-12
Arrival Date 2010-11-25
Principal Scientist(s)Andrew Rees (Plymouth Marine Laboratory)
Ship RRS James Cook

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
Q value below limit of quantification