Metadata Report for BODC Series Reference Number 1222799

Metadata Summary

Data Description

Data Category Surface temp/sal
Instrument Type
Turner 10-AU chlorophyll field fluorometer  fluorometers
Sea-Bird SBE 21 Thermosalinograph  thermosalinographs; water temperature sensor; salinity sensor
Trimble 4000DS Global Positioning System receiver  Differential Global Positioning System receivers
Instrument Mounting research vessel
Originating Country United Kingdom
Originator Dr Tony Bale
Originating Organization Plymouth Marine Laboratory
Processing Status banked
Online delivery of data Download available - Ocean Data View (ODV) format
Project(s) Atlantic Meridional Transect (AMT)

Data Identifiers

Originator's Identifier AMT2_SURF
BODC Series Reference 1222799

Time Co-ordinates(UT)

Start Time (yyyy-mm-dd hh:mm) 1996-04-22 12:10
End Time (yyyy-mm-dd hh:mm) 1996-05-22 07:17
Nominal Cycle Interval 30.0 seconds

Spatial Co-ordinates

Start Latitude 51.69170 S ( 51° 41.5' S )
End Latitude 50.28710 N ( 50° 17.2' N )
Start Longitude 57.82370 W ( 57° 49.4' W )
End Longitude 4.21400 W ( 4° 12.8' W )
Positional Uncertainty 0.0 to 0.01 n.miles
Minimum Sensor or Sampling Depth 6.0 m
Maximum Sensor or Sampling Depth 6.0 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)
ALATGP011DegreesLatitude north (WGS84) by unspecified GPS system
ALONGP011DegreesLongitude east (WGS84) by unspecified GPS system
CPHLUT011Milligrams per cubic metreConcentration of chlorophyll-a {chl-a CAS 479-61-8} per unit volume of the water body [particulate >unknown phase] by through-flow fluorometer plumbed into non-toxic supply and calibration against sample data
FVLTTDZC1DimensionlessRaw signal (arbitrary scale) of instrument output by autoranging chlorophyll fluorometer and correction to a common scale
PSALSG011DimensionlessPractical salinity of the water body by thermosalinograph and computation using UNESCO 1983 algorithm and calibration against independent measurements
TEMPSG011Degrees CelsiusTemperature of the water body by thermosalinograph and verification against independent measurements

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

RRS James Clark Ross AMT2 (JR13) Underway Hydrographic Data Quality Report

Further to the processing documentation there are no additional known data quality issues.

Data Access Policy

Public domain data

These data have no specific confidentiality restrictions for users. However, users must acknowledge data sources as it is not ethical to publish data without proper attribution. Any publication or other output resulting from usage of the data should include an acknowledgment.

The recommended acknowledgment is

"This study uses data from the data source/organisation/programme, provided by the British Oceanographic Data Centre and funded by the funding body."

Narrative Documents

Turner Designs 10AU Field Fluorometer

The Turner Designs 10AU is designed for continuous-flow monitoring or discrete sample analyses of fluorescent species. A variety of optical kits with appropriate filters and lamps are available for a wide range of applications. Individual filters and lamps are also available for customised applications.

Standard optical kits include those for chlorophyll-a (extracted and/or in vivo), phycocyanin, phycoerythrin, CDOM, ammonium, rhodamine and fluorescein dye tracing, crude oil, refined oil, histamine and optical brighteners.

The instrument's light source is a 4 watt lamp and the detector is a photomultiplier tube with a standard detection range of 300-650 nm. A red-sensitive version with a detetion range of 185-970 nm is also available.


Operating temperature 0 to 55°C
Detector PhotoMultiplier Tube

300 to 650 nm (standard)

185 to 870 nm (Red)

Detection Limits:
Extracted Chlorophyll-a
Rhodamine WT Dye
Fluorescein Dye

0.025 µg L-1
0.01 ppb (in potable water)
0.01 ppb (in potable water)
Linear range:
Extracted Chlorophyll-a
Rhodamine WT Dye
Fluorescein Dye

0 to 250µg L-1
0 to 250 ppb
0 to 250 ppb

Further details can be found in the manufacturer's specification sheet.

Trimble 4000DS Global Positioning System receiver

The Trimble 4000DS Differential Surveyor is similar to the 4000RS (a Maxwell-based receiver that is oriented toward precision positioning applications. It is intended for use as a DGPS base station, generating RTCM-104 corrections). The 4000Ds can apply RTCM-104 corrections to the satellite data it receives in order to generate accurate position fixes in real time.

RRS James Clark Ross AMT2 (JR13) Underway Hydrographic Instrumentation

The instrumentation has been collated from various sources as historic notation of instrumentation was not well maintained. Care may be required if making assumptions based on the instruments used.

The following instruments were used for hydrographic measurements:

Instrument Name Model Serial Number Parameter(s)
Trimble 4000DS Global Positioning System receiver 4000DS N/A Latitude and Longtiude
Turner 10-AU chlorophyll field fluorometer Model 10 N/A Chlorophyll/Fluoresence
Sea-Bird SBE 21 Thermosalinograph SBE 21 N/A Temperature, Conductivity/Salinity, Pressure/Depth

RRS James Clark Ross AMT2 (JR13) Underway Hydrographic Data Processing Procedures

Originator's Data Processing

Raw data were logged as ADC counts on the ship's computers. They were converted into engineering units using initial manufacturers' calibrations. Conductivity and two temperature channels were produced from the thermosalinograph counts using laboratory calibrations on board ship.

The data from the fluorometer was logged into the JCR Ocean Logger system using the internal A/D converter and range output. The fluorometer had an autoranging capability which maximises the sensitivity of the instrument in areas of different chlorophyll concentrations.

The data were submitted to BODC in RVS internal format for post-cruise processing and data banking.

BODC Data Processing


Underway data files were merged into a single binary merge file using time as the primary linking key. The time span of the file was from 22/04/1996 12:10:00 to 22/05/1996 07:17:30, with a sampling interval of 30 seconds.

Salinity was computed from housing temperature and conductivity using the UNESCO 1978 Practical Salinity Scale (Fofonoff and Millard, 1982).


Each data channel was inspected on a graphics workstation and any spikes or periods of dubious data were flagged. The power of the workstation software was used to carry out comparative screening checks between channels by overlaying data channels. A map of the cruise track was simultaneously displayed in order to take account of the oceanographic context.

Data processing, correction and calibration

Sample Calibrations


Temperature and salinity readings from the thermosalinograph were compared with precision reversing thermometers mounted on the CTD frame at the 7 m position. The calibration exercise was carried out by Tony Bale (PML), and the results are presented in the AMT2 cruise report. The station at which each comparison was made is provided, but it is not known whether it was carried out during the first or second CTD cast on station, so the data are not present in the database. However, they are presented in the table below.

Station Thermosalinograph temp (°C) Reversing thermometer temp (°C) Difference (error on thermosalinograph) (°C)
114 7.31 7.336 -0.026
115 13.39 12.765 0.625
116 19.07 19.097 -0.027
120 20.73 20.72 0.01
121 20.42 20.45 -0.03
122 23.27 23.27 0
123 24.65 24.52 0.13
124 25.21 25.17 0.04
125 27.42    
126 28.21 28.13 0.08
127 28.55 28.47 0.08
128 28.6 28.56 0.04
129 28.38 28.35 0.03
130 28.49 28.45 0.04
131 28.62 28.55 0.07
132 26.86 26.74 0.12
133 26.17 26.11 0.06

The mean and standard deviation of the offsets, for all samples, are 0.0776 and 0.1538 respectively. If the outlying values are removed (those shown in bold), the mean and standard deviation is 0.0282 and 0.0398.

The underway sea temperature channel was also compared with averaged surface values extracted from CTD profiles to 7 metres. The 49 samples gave a small offset of -0.00143 °C between CTD and surface underway data with a standard deviation 0.0310. However, the calibration sample data were derived from averaging several data points; some of these showed a high degree of variability in the underway or CTD data at the time of the calibration point (having a standard deviation of 0.02 °C or greater). When these samples were removed from the data set, the mean offset was 0.000511 °C, with a standard deviation of 0.02366 (N=45). Due to the low offset and relatively high standard deviation of the calibration samples, no correction was required for the original temperature channel.


Salinity values from the thermosalinograph were compared with the salinity of samples taken from the non-toxic supply measured on the Autolab precision salinometer. The calibration exercise was carried out by Tony Bale (PML).

The data are presented in the table below (taken from the AMT2 cruise report).

Station Thermosalinograph salinity Salinometer salinity Difference (thermosalinograph error)
114 33.986 33.978 0.008
115 34.009 34.022 -0.013
116 35.891 35.904 -0.013
120 36.054 36.055 -0.001
121 35.772 35.796 -0.024
122 36.305 36.358 -0.053
123 36.716 36.659 0.057
124 36.84 36.811 0.029
125 37.36 37.32 0.04
126 37.325 37.26 0.065
127 36.695 36.682 0.013
128 36.406 36.39 0.016
129 35.729 35.724 0.005
130 35.942 35.93 0.012
131 35.403 35.362 0.041
132 35.925 35.942 -0.017
133 36.044 36.039 0.005

The mean and standard deviation of the offset values are 0.01 and 0.03 respectively.

Surface CTD data were also extracted to calibrate the underway salinity. The offset was -0.00293 PSU, with a standard deviation of 0.00996 (N=44). The low offset indicated that the salinity channel required no correction to be applied to the data.


As the data logged from the fluorometer did not contain corrections for range changes, the exact time and scale of each range change was noted during the screening process at BODC. The data were then adjusted to the same range throughout the cruise, using the correction fluorc = fluor*(31.6/range).

Start date/time End date/time Fluorometer range
22/04/1996 12:10:00 29/04/1996 17:45:00 03.16
29/04/1996 17:45:30 12/05/1996 20:54:30 10.00
12/05/1996 20:55:00 19/05/1996 19:24:00 03.16
19/05/1996 19:24:30 22/05/1996 07:17:30 01.00

After corrections were made for the range changes, the data were compared with fluorometric chlorophyll-a concentrations measured on samples taken from the non-toxic supply. The resulting relationship was used to calibrate the underway fluorometer.

     Calibrated chlorophyll-a (mg m-3) = 0.00263 * fluorometer value - 0.0534     (n=255, R2=73.3%)

The effect of quenching was assessed by adding PAR into a multiple regression. There was no improvement in the fit, so no correction for quenching was made.


Fofonoff, N.P. and Millard Jr., R.C., 1982. Algorithms for Computation of Fundamental Properties of Seawater. UNESCO Technical Papers in Marine Science, 44.

SeaBird 21 SeaCAT Thermosalinograph SBE 21

The SBE21 is an externally powered instrument used to determine sea surface temperature and conductivity from underway vessels. Data is simultaneously stored in memory and output to a computer in real-time. Typically mounted on the ship's seawater intake, the SBE21 connects to an AC-powered interface box near a computer. TH interface box provides power and an isolated data interface, and contains a NMEA 0183 port for appending navigation data. There are options for auxiliary sensors using the RS-232 interface for a SBE32 temperature sensor and for four single-ended or two differential 0-5 volt A/D input channels for voltage output auxiliary sensors.

Components include internal-field conductivity cell eliminates proximity effects, which also permits use of expendable anti-foulant devices, for long-term bio-fouling protection. The thermistor is aged and pressure-protected.


  Conductivity Temperature, primary Temperature, SBE38 remote
Range 0 to 7 S/m -5 to 35°C -5 to 35°C
Initial Accuracy ±0.001 S/m ±0.01°C ±0.001°C
Resolution 0.000 S/m 0.001°C 0.0003°C

More information may be found in the SBE21 brochure.

Project Information

The Atlantic Meridional Transect (AMT) - Phase 1 (1995-2000)

Who was involved in the project?

The Atlantic Meridional Transect (AMT) programme was designed by and implemented as a collaboration between Plymouth Marine Laboratory (PML) and Southampton Oceanography Centre (SOC). The programme was hosted by Plymouth Marine Laboratory and involved additional researchers from UK and international universities throughout its duration.

What was the project about?

When AMT began in 1995 the programme provided a platform for international scientific collaboration, including the calibration and validation of SeaWiFs measurements and products. The programme provided an exceptional opportunity for nationally and internationally driven collaborative research and provided a platform for excellent multi-disciplinary oceanographic research. As an in situ observation system, the data collected by the AMT consortium informed on changes in biodiversity and function of the Atlantic ecosystem during this period of rapid change to our climate and biosphere.

The scientific aims were to assess:

When was the project active?

The first phase of the AMT programme ran from 1995 to 2000 and consisted of a total of 12 cruises. A second phase of funding allowed the project to continue for the period 2002 to 2006 with a further 6 cruises.

Brief summary of the project fieldwork/data

The AMT programme undertook biological, chemical and physical oceanographic research during the annual return passage of the RRS James Clark Ross between the UK and the Falkland Islands or the RRS Discovery between the UK and Cape Town, a distance of up to 13,500 km. This transect crossed a range of ecosystems from sub-polar to tropical and from euphotic shelf seas and upwelling systems to oligotrophic mid-ocean gyres. The transect route was covered north-south in September/October and south-north in April/May of each year.

The measurements of hydrographic and bio-optical properties, plankton community structure and primary production completed on the first 12 transects (1995-2000) represent the most coherent set of repeated biogeochemical observations over ocean basin scales. This unique dataset has led to several important discoveries concerning the identification of oceanic provinces, validation of ocean colour algorithms, distributions of picoplankton, identifying new regional sinks of pCO2 and variability in rates of primary production and respiration.

Who funded the project?

The programme was funded by the Natural Environment Research Council (NERC) and further support was received from the National Aeronautics and Space Administration (NASA) with equipment and funding from the Sea-viewing Wild Field-of-view Sensor (SeaWiFS) project.

Data Activity or Cruise Information


Cruise Name JR19960422 (AMT2, JR13)
Departure Date 1996-04-22
Arrival Date 1996-05-22
Principal Scientist(s)David Robins (Plymouth Marine Laboratory)
Ship RRS James Clark Ross

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