Metadata Report for BODC Series Reference Number 1221575

Metadata Summary

Data Description

Data Category Water column chemistry
Instrument Type
Los Gatos Research N2O and CO 23d ICOS Analyser  cavity enhanced absorption spectrometers
Instrument Mounting research vessel
Originating Country United Kingdom
Originator Ms Imke Grefe
Originating Organization University of East Anglia School of Environmental Sciences
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 N2O_FROM_MAT_PCO2
BODC Series Reference 1221575

Time Co-ordinates(UT)

Start Time (yyyy-mm-dd hh:mm) 2010-10-26 05:45
End Time (yyyy-mm-dd hh:mm) 2010-11-19 03:48
Nominal Cycle Interval 10.0 seconds

Spatial Co-ordinates

Start Latitude 23.76980 N ( 23° 46.2' N )
End Latitude 38.73547 S ( 38° 44.1' S )
Start Longitude 41.10770 W ( 41° 6.5' W )
End Longitude 41.22140 W ( 41° 13.3' W )
Positional Uncertainty 0.0 to 0.01 n.miles
Minimum Sensor or Sampling Depth 5.0 m
Maximum Sensor or Sampling Depth 5.0 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
ALATGP011DegreesLatitude north relative to WGS84 by unspecified GPS system
ALONGP011DegreesLongitude east relative to WGS84 by unspecified GPS system
MXRM2OMS1Nanomoles per litreMixing ratio (equilibrated marine sample) of nitrous oxide {N2O CAS 10024-97-2}

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 RRS James Cook (JC053) Underway Dissolved Nitrous Oxide Data Quality Report

Data Quality Report

The data had undergone quality control by the originator. Limited BODC flagging was applied.

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

Los Gatos Research (LGR) Inc. N2O and CO Analyser

Basic Information

The Los Gatos Research (LGR) N2O/CO Analyser can measure ambient levels of N2O/CO in real time with a precision better than 0.1 ppb in 1 second. The model N2O/CO-23-d reports water vapour as mole fraction simultaneously. The analyser makes use of LGR's Off-axis Internal Cavity Output Spectroscopy (OA-ICOS), which is a laser absorption technology.

Performance Specifications

Precision(1σ, 1 second / 3 minutes): N2O: 0.1 ppb / 0.050 ppb
CO: 0.1 ppb / 0.050 ppb
H2O: 50 ppm / 10 ppm
Measurement Rates: All parameters measured simultaneously at user-selectable rates up to 10 Hz (optional pump required for flow rates >1Hz)
Maximum Drift (Exhanced Performance models)(15 min average, at STP, over 24 hrs): N2O: 0.1 ppb
CO: 0.1 ppb
H2O: 50 ppm or 1% reading, whichever greater
Linear Dynamic Range (meets all specs): N2O: 5 - 4000 ppb
CO: 5 - 4000 ppb
Dynamic Range: N2O: 0 - 10 ppm
CO: 0 - 10 ppm
Temperature/Humidity: Sample Temperature: -30 to 50 °C
Operating Temperature:

10 - 35 °C (Standard Model)

0 - 45 °C (Enhanced PerformanceModel)

Ambient Humidity: non-condensing (0-100% RH)

Other information

Dimensions (rackmount compatible): 19" x 30" x 14" (Standard Model)
17" x 34" x 17.5" (Enhanced Performance Model)
Weight: 36 kg (Standard Model)
68 kg (Enhanced Performance Model)
Fittings: Inlet: 3/8"
Outlet (internal pump): 1/4"
Outlet (optional external vacuum pump): 1/2"

Further information may be found in the LGR specification sheet.

AMT20 RRS James Cook (JC053) Underway Dissolved Nitrous Oxide Instrumentation

Instrument Model number Parameter
Los Gatos Research N2O/CO ICOS Analyser N2O/CO-23d Dissolved Nitrogen Oxide

AMT20 RRS James Cook (JC053) Underway Dissolved Nitrous Oxide Processing Document

Originator's Processing

Measurements and Methods

An N2O/CO ICOS analyser was coupled with a percolating packed bed equilibrator for continuous measurements in the surface ocean. Water flow through the equilibrator from the ship's pumped seawater supply was set to 1.8 L min-1. The water temperature in the equilibrator and the headspace were measured with two Pt100 temperature probes, and recorded every 10 seconds to monitor temperature changes between the seawater intake and equilibrator. Water vapour in the circulating gas headspace was reduced with a cold trap (5°C). Residual H2O was measured by the instrument for calculation of N2O dry mole ratios. A basic linear interpolation was applied to the latitude and longitude to get a higher spatial resolution.


Dried Air with 323.7 nmol mol-1 N2O was used as a working reference, calibrated against IMECC/NOAA primary standards. Every 8 hours, the analyser was calibrated by switching from equilibrator headspace to the reference gas for 20 minutes. This was followed by another reference measurement after 40 minutes to assess short-time drift. Only the last 5 minutes of each measurement were analysed to allow for complete flushing of the measurement cell. For the first 15 minutes after switching back to the equilibrator headspace or to the marine air measurements were not used for evaluation. Instrument offset and drift were corrected with a linear interpolation between reference gas measurements.

Originator's Quality Control

As mentioned above for calibrations, the first 15 minutes after a change of gas streams were discarded from the evaluation to allow for measurement cell and equilibrator flushing. The same was done after any changes to the setup (e.g. re-adjustment of water flow through equilibrator, pausing the analyser for maintenance). When change of water flow through the equilibrator was noticed, data back to the last observation of correct water flow were flagged.

BODC Processing

Data were submitted to BODC as a .mat file containing the data as 4 double arrays, consisting of date and time, N2O, latitude and longitude. In addition to the .mat file a Microsoft Word document was submitted containing the methodology. The data was 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 Name Originator's Units BODC Parameter Code BODC Units BODC Description
N2O partial pressure in ppb Parts per billion (ppb) MXRM2OMS Nanomoles per litre Mixing ratio (equilibrated marine sample) of nitrous oxide
Latitude   ALATGP01 Degrees Latitude north (WGS84) by unspecified GPS system
Longitude   ALONGP01 Degrees Longitude east (WGS84) by unspecified GPS system


Suspect data was flagged 'M' as suspect following screening.

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