Metadata Report for BODC Series Reference Number 1222935


Metadata Summary

Data Description

Data Category Surface temp/sal
Instrument Type
NameCategories
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 Prof Jim Aiken
Originating Organization Plymouth Marine Laboratory
Processing Status banked
Project(s) Atlantic Meridional Transect (AMT)
 

Data Identifiers

Originator's Identifier AMT6_SURF
BODC Series Reference 1222935
 

Time Co-ordinates(UT)

Start Time (yyyy-mm-dd hh:mm) 1998-05-15 12:00
End Time (yyyy-mm-dd hh:mm) 1998-06-16 08:41
Nominal Cycle Interval 30.0 seconds
 

Spatial Co-ordinates

Start Latitude 33.63250 S ( 33° 37.9' S )
End Latitude 53.58640 N ( 53° 35.2' N )
Start Longitude 18.01410 E ( 18° 0.8' E )
End Longitude 0.02860 E ( 0° 1.7' E )
Positional Uncertainty 0.0 to 0.01 n.miles
Minimum Sensor Depth 6.0 m
Maximum Sensor Depth 6.0 m
Minimum Sensor Height -
Maximum Sensor Height -
Sea Floor Depth -
Sensor Distribution Fixed common depth - All sensors are grouped effectively at the same depth which is effectively fixed for the duration of the series
Sensor Depth Datum Approximate - Depth is only approximate
Sea Floor Depth Datum -
 

Parameters

BODC CODE Rank Units Short Title Title
AADYAA01 1 Days Date(Loch_Day) Date (time from 00:00 01/01/1760 to 00:00 UT on day)
AAFDZZ01 1 Days Time(Day_Fract) Time (time between 00:00 UT and timestamp)
ALATGP01 1 Degrees Lat_GPS Latitude north (WGS84) by unspecified GPS system
ALONGP01 1 Degrees Lon_GPS Longitude east (WGS84) by unspecified GPS system
FVLTTDZC 1 Dimensionless Fl_output_corr Instrument output (arbitrary scale) by autoranging chlorophyll fluorometer and correction to a common scale
FVLTTDZX 1 Dimensionless Fl_output Instrument output (arbitrary scale) by autoranging chlorophyll fluorometer
PSALSG01 1 Dimensionless P_sal_TSG_calib Practical salinity of the water body by thermosalinograph and computation using UNESCO 1983 algorithm and calibration against independent measurements
TEMPSG01 1 Degrees Celsius CalTSGTmp Temperature 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 AMT6 (JR32) 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.

Specifications

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 AMT6 (JR32) 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, Presuure/Depth

RRS James Clark Ross AMT6 (JR32) 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

Reformatting

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 15/05/1998 12:00:30 to 16/06/1998 08:41:30, 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).

Screening

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

The underway sea temperature channel was compared with averaged surface values extracted from CTD profiles up to 7 metres. The 49 samples gave a very small offset of -0.017 °C between CTD and surface underway data with a standard deviation of 0.046. As the offset was smaller than the standard deviation, no correction has been applied to the underway data.

Salinity

The salinity channel was calculated from conductivity and housing temperature. During screening, it was obvious that there was a problem with the salinity channel as it showed disturbance whenever there was a change in temperature. The housing temperature and conductivity channels were compared and a lag was found between the two. The response of conductivity lagged the housing temperature by 3 datacycles (or 90 seconds). To improve the quality of the salinity data, the conductivity and housing temperature channels were realigned by moving the conductivity back 3 datacyles. The salinity channel was then recomputed.

Surface CTD data were also extracted to calibrate the underway salinity. This indicated a problem with the underway data set that was not resolved. The salinity data should be used with caution.

Fluorescence

The Turner Designs fluorometer operated on different range settings throughout the cruise. The points at which the range setting changed can usually be identified during screening by looking for abrupt jumps in the signal with a magnitude of approximately 3. This was difficult to do during AMT6 and for this reason the data were not calibrated against discrete chl-a measurements.

Data Quality

The salinity values are suspect, particularly between 16/07/1998 to 25/07/1998. Users should use surface salinity data from CTD casts if possible.

It is not known what correction was applied to the raw fluorometer to output the results to a common scale. Users are advised to use the data with care.

References

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.

Specifications

  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

Cruise Name JR19980514 (AMT6, JR32)
Departure Date 1998-05-14
Arrival Date 1998-06-16
Principal Scientist(s)James Aiken (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