Metadata Report for BODC Series Reference Number 1012766


Metadata Summary

Data Description

Data Category CTD or STD cast
Instrument Type
NameCategories
Sea-Bird SBE 911plus CTD  CTD; water temperature sensor; salinity sensor
Instrument Mounting lowered unmanned submersible
Originating Country United Kingdom
Originator Dr Stuart Cunningham
Originating Organization National Oceanography Centre, Southampton
Processing Status banked
Project(s) Rapid Climate Change Programme
RAPIDMOC
RAPID-WATCH
 

Data Identifiers

Originator's Identifier CTD_DI344_026_2DB
BODC Series Reference 1012766
 

Time Co-ordinates(UT)

Start Time (yyyy-mm-dd hh:mm) 2009-11-15 22:04
End Time (yyyy-mm-dd hh:mm) 2009-11-15 22:30
Nominal Cycle Interval 2.0 decibars
 

Spatial Co-ordinates

Latitude 26.50170 N ( 26° 30.1' N )
Longitude 70.99670 W ( 70° 59.8' W )
Positional Uncertainty Unspecified
Minimum Sensor Depth 6.95 m
Maximum Sensor Depth 1158.1 m
Minimum Sensor Height 4337.0 m
Maximum Sensor Height 5488.15 m
Sea Floor Depth 5495.1 m
Sensor Distribution Variable common depth - All sensors are grouped effectively at the same depth, but this depth varies significantly during the series
Sensor Depth Datum Approximate - Depth is only approximate
Sea Floor Depth Datum Approximate - Depth is only approximate
 

Parameters

BODC CODE Rank Units Title
ACYCAA01 1 Dimensionless Sequence number
CNDCST01 1 Siemens per metre Electrical conductivity of the water body by CTD
CNDCST02 1 Siemens per metre Electrical conductivity of the water body by CTD (sensor 2)
PRESPR01 1 Decibars Pressure (spatial co-ordinate) exerted by the water body by profiling pressure sensor and corrected to read zero at sea level
PSALCC01 1 Dimensionless Practical salinity of the water body by CTD and computation using UNESCO 1983 algorithm and calibration against independent measurements
PSALCU02 1 Dimensionless Practical salinity of the water body by CTD and computation using UNESCO 1983 algorithm and NO calibration against independent measurements
TEMPCU01 1 Degrees Celsius Temperature of the water body by CTD and NO verification against independent measurements
TEMPCU02 1 Degrees Celsius Temperature of the water body by CTD and NO 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


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

RAPID Cruise D344 CTD instrument description

CTD unit and auxiliary sensors

The CTD system used on cruise D344 was a NOC 24-way stainless steel frame system (s/n SBE CTD1415) consisting of a Sea-Bird 911 plus, with a Sea-Bird 32 carousel. The water samples were Ocean Test Equipment 10L ES-115B and were used in alternate positions on the CTD frame. This was to allow moored instruments to be strapped to the frame for calibration purposes. During the cruise various problems with sensors required them to be replaced on the CTD frame (see Section 11.1 of the D344 cruise report). The table below shows which sensors were attached to the CTD frame and on which casts.

Sensor Serial Number Casts Last calibration date
SBE 911+ deck unit 0587 1 -
SBE 911+ deck unit 0588 2-27 -
SBE 32 carousel 0423 1-27 09 June 2008
Primary Temperature SBE-03P 4151 1-27 25 June 2009
Secondary Temperature SBE-03P 4782 1-9 16 May 2009
Secondary Temperature SBE-03P 2674 10-27 08 May 2009
Primary Conductivity SBE-04C 2571 1-2 08 July 2009
Primary Conductivity SBE-04C 3054 3-27 25 June 2009
Secondary Conductivity SBE-04C 2841 1-27 25 August 2009
Pressure-Digiquartz 90573 1-27 20 October 2008
Benthos PSA-916T Altimeter 47597 1-2 -
Tritech PA200 Altimeter 6196.118171 3-27 15 November 2006

The salinity samples from the CTD were analysed during the cruise using a Guildline Autosal model 8400B(serial number 68958).

Sea-Bird Electronics SBE 911 and SBE 917 series CTD profilers

The SBE 911 and SBE 917 series of conductivity-temperature-depth (CTD) units are used to collect hydrographic profiles, including temperature, conductivity and pressure as standard. Each profiler consists of an underwater unit and deck unit or SEARAM. Auxiliary sensors, such as fluorometers, dissolved oxygen sensors and transmissometers, and carousel water samplers are commonly added to the underwater unit.

Underwater unit

The CTD underwater unit (SBE 9 or SBE 9 plus) comprises a protective cage (usually with a carousel water sampler), including a main pressure housing containing power supplies, acquisition electronics, telemetry circuitry, and a suite of modular sensors. The original SBE 9 incorporated Sea-Bird's standard modular SBE 3 temperature sensor and SBE 4 conductivity sensor, and a Paroscientific Digiquartz pressure sensor. The conductivity cell was connected to a pump-fed plastic tubing circuit that could include auxiliary sensors. Each SBE 9 unit was custom built to individual specification. The SBE 9 was replaced in 1997 by an off-the-shelf version, termed the SBE 9 plus, that incorporated the SBE 3 plus (or SBE 3P) temperature sensor, SBE 4C conductivity sensor and a Paroscientific Digiquartz pressure sensor. Sensors could be connected to a pump-fed plastic tubing circuit or stand-alone.

Temperature, conductivity and pressure sensors

The conductivity, temperature, and pressure sensors supplied with Sea-Bird CTD systems have outputs in the form of variable frequencies, which are measured using high-speed parallel counters. The resulting count totals are converted to numeric representations of the original frequencies, which bear a direct relationship to temperature, conductivity or pressure. Sampling frequencies for these sensors are typically set at 24 Hz.

The temperature sensing element is a glass-coated thermistor bead, pressure-protected inside a stainless steel tube, while the conductivity sensing element is a cylindrical, flow-through, borosilicate glass cell with three internal platinum electrodes. Thermistor resistance or conductivity cell resistance, respectively, is the controlling element in an optimized Wien Bridge oscillator circuit, which produces a frequency output that can be converted to a temperature or conductivity reading. These sensors are available with depth ratings of 6800 m (aluminium housing) or 10500 m (titanium housing). The Paroscientific Digiquartz pressure sensor comprises a quartz crystal resonator that responds to pressure-induced stress, and temperature is measured for thermal compensation of the calculated pressure.

Additional sensors

Optional sensors for dissolved oxygen, pH, light transmission, fluorescence and others do not require the very high levels of resolution needed in the primary CTD channels, nor do these sensors generally offer variable frequency outputs. Accordingly, signals from the auxiliary sensors are acquired using a conventional voltage-input multiplexed A/D converter (optional). Some Sea-Bird CTDs use a strain gauge pressure sensor (Senso-Metrics) in which case their pressure output data is in the same form as that from the auxiliary sensors as described above.

Deck unit or SEARAM

Each underwater unit is connected to a power supply and data logging system: the SBE 11 (or SBE 11 plus) deck unit allows real-time interfacing between the deck and the underwater unit via a conductive wire, while the submersible SBE 17 (or SBE 17 plus) SEARAM plugs directly into the underwater unit and data are downloaded on recovery of the CTD. The combination of SBE 9 and SBE 17 or SBE 11 are termed SBE 917 or SBE 911, respectively, while the combinations of SBE 9 plus and SBE 17 plus or SBE 11 plus are termed SBE 917 plus or SBE 911 plus.

Specifications

Specifications for the SBE 9 plus underwater unit are listed below:

Parameter Range Initial accuracy Resolution at 24 Hz Response time
Temperature -5 to 35°C 0.001°C 0.0002°C 0.065 sec
Conductivity 0 to 7 S m-1 0.0003 S m-1 0.00004 S m-1 0.065 sec (pumped)
Pressure 0 to full scale (1400, 2000, 4200, 6800 or 10500 m) 0.015% of full scale 0.001% of full scale 0.015 sec

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

BODC CTD Screening

BODC screen both the series header qualifying information and the parameter values in the data cycles themselves.

Header information is inspected for:

Documents are written by BODC highlighting irregularities that cannot be resolved.

Data cycles are inspected using depth series plots of all parameters. These presentations undergo screening to detect infeasible values within the data cycles themselves and inconsistencies when comparing adjacent data sets displaced with respect to depth, position or time.

Values suspected of being of non-oceanographic origin may be tagged with the BODC flag denoting suspect value.

The following types of irregularity, each relying on visual detection in the time series plot, are amongst those that may be flagged as suspect:

If a large percentage of the data is affected by irregularities, deemed abnormal, then instead of flagging the individual suspect values, a caution may be documented.

The following types of inconsistency are detected automatically by software:

Inconsistencies between the characteristics of the data set and those of its neighbours are sought, and where necessary, documented. This covers inconsistencies in the following:

This screening of the parameter values seeks to confirm the qualifying information and the source laboratory's comments on the series. In screening and collating information, every care is taken to ensure that errors of BODC's making are not introduced.

RAPID Cruise D344 BODC CTD data processing

The data arrived at BODC in 27 MSTAR format files representing the CTD casts conducted during cruise D344. The data contained in the files are the downcast data averaged to a 2db pressure grid. The casts were reformatted to BODC's internal NetCDF format. The following table shows the mapping of variables within the MSTAR files to appropriate BODC parameter codes:

Originator's variable Units Description BODC parameter code Units Comments
press dbar Pressure exerted by the water column PRESPR01 dbar Manufacturer's calibration applied.
temp °C Temperature of the water column by CTD (Primary sensor) TEMPCU01 °C ITS-90
temp2 °C Temperature of the water column by CTD (Secondary sensor) TEMPCU02 °C ITS-90
psal - Practical salinity of the water column (Primary sensor data) PSALCC01 - Calculated by data originator using calibrated conductivity.
psal2 - Practical salinity of the water column (Secondary sensor data) PSALCU02 - Calculated by data originator using uncalibrated conductivity.
potemp °C Potential temperature of the water column (Primary sensor) POTMCV01 °C Not transferred
potemp2 °C Potential temperature of the water column (Secondary sensor) POTMCV02 °C Not transferred
cond mS/cm Electrical conductivity of the water column (Primary sensor) CNDCST01 S/m /10. Calibrated by data originator with discrete salinity samples.
cond2 mS/cm Electrical conductivity of the water column (Secondary sensor) CNDCST02 S/m /10
depth metres Depth below surface converted from pressure using UNESCO algorithm DEPHPR01 metres Not transferred
time seconds Time in seconds since the origin defined in the metadata field data_time_origin - - Not transferred

The reformatted data were visualised using the in-house EDSERPLO software. Suspect data were marked by adding an appropriate quality control flag, and missing data marked by setting both the data to an appropriate value and setting the quality control flag.

Detailed metadata and documentation were compiled and linked to the data.

RAPID Cruise D344 Originator's CTD data processing

Sampling Strategy

A total of 27 CTD casts were performed during the cruise along approximately 26.5°N, which includes the Eastern boundary, Mid Atlantic Ridge and Western boundary sections of the RAPIDMOC array. On each cast, up to 12 SBE37 MicroCATs were attached to the frame for calibration purposes. The CTD casts provided start-point calibrations for instruments to be deployed and end-point calibrations for recovered instruments. For recovered instruments that were re-deployed, the post-deployment cast provided a pre-deployment calibration. The instruments were set to the fastest sampling rate and the CTD lowered as normal. On the upcast, the bottle stops were increased to 5 minutes to allow time for stabilisation and the provision of more accurate data. To allow the instruments to be attached to the CTD frame using bespoke attachments, up to 12 sample bottles were removed on all casts.

Data Processing

Raw CTD data were transferred from the Sea-Bird deck unit to a LINUX machine via Sea-Bird software. The binary files are converted using Sea-Bird processing software (SBE Data Processing v7.18). Physical units were calculated from the frequency data using the manufacturer's calibration routines and the data converted to ASCII format. The ASCII files were converted to MSTAR format and MEXEC programs were run to reduce the frequency of the data from 24Hz to 1Hz, and for the downcast to be averaged to a 2db pressure grid. A calibration was produced for the CTD primary conductivity sensor by merging the salinity sample data with the CTD data. Details of the MEXEC programs used and further details of the processing performed can be found in Cunningham et al. (2010).

Field Calibrations

Independent salinity samples, obtained from the bottles on the CTD frame, were used to calibrate the CTD salinity data. Bottle samples with incorrect conductivities were identified and removed from the calibration. Data points were excluded if the residual (bottle conductivities minus CTD conductivities) was outside the limits -0.002 to 0.008 mS/cm for casts 3-27 and exceeded 0.015 mS/cm for casts 1 and 2. Also if the residual was larger than 3 standard deviations of the new station mean, the data were excluded. Out of 310 samples, 16 were removed by these criteria.

A slope correction to account for sensor drift was applied such that CCTDcorrected1=CCTD*K. Due to a change in the primary conductivity sensor (after cast 2) and grouping residuals that have similar offsets, K was calculated for groups of casts namely, casts 1-2, 4-7, 8-13 and 14-27, the values of K being 1.000232, 1.000043, 1.000010 and 1.000027, respectively. Cast 3 was excluded from the block averaging because it was a shallow cast with short bottle stops. Hence, the K value from casts 4-7 was applied to cast 3.

A quadratic fit of residual difference against pressure was then applied to remove the increase in residual with depth. The quadratic fit applied was

ΔC = Cbot - CCTD = a2p2 + a1p + a0

where a2=3.7 x 10-11 ± 2.5 x 10-11 mS cm-1db-2, a1= 2.0 x 10-7 ± 1.4 x 10-7mS cm-1db-1 and a0=-7.1 x 10-4 ± 1.5 x 10-4 mS/cm.

References

Cunningham, S.A., Wright, P.G. (ed.) (2010) RRS Discovery Cruise D344, 21 Oct-18 Nov 2009. RAPID Mooring cruise report. Southampton, UK, National Oceanography Centre, Southampton, 225pp. (National Oceanography Centre Southampton Cruise Report, 51)


Project Information

Rapid Climate Change (RAPID) Programme

Rapid Climate Change (RAPID) is a £20 million, six-year (2001-2007) programme of the Natural Environment Research Council (NERC). The programme aims to improve our ability to quantify the probability and magnitude of future rapid change in climate, with a main (but not exclusive) focus on the role of the Atlantic Ocean's Thermohaline Circulation.

Scientific Objectives

Projects

Overall 38 projects have been funded by the RAPID programme. These include 4 which focus on Monitoring the Meridional Overturning Circulation (MOC), and 5 international projects jointly funded by the Netherlands Organisation for Scientific Research, the Research Council of Norway and NERC.

The RAPID effort to design a system to continuously monitor the strength and structure of the North Atlantic Meridional Overturning Circulation is being matched by comparative funding from the US National Science Foundation (NSF) for collaborative projects reviewed jointly with the NERC proposals. Three projects were funded by NSF.

A proportion of RAPID funding as been made available for Small and Medium Sized Enterprises (SMEs) as part of NERC's Small Business Research Initiative (SBRI). The SBRI aims to stimulate innovation in the economy by encouraging more high-tech small firms to start up or to develop new research capacities. As a result 4 projects have been funded.


Monitoring the Meridional Overturning Circulation at 26.5N (RAPIDMOC)

Scientific Rationale

There is a northward transport of heat throughout the Atlantic, reaching a maximum of 1.3PW (25% of the global heat flux) around 24.5°N. The heat transport is a balance of the northward flux of a warm Gulf Stream, and a southward flux of cooler thermocline and cold North Atlantic Deep Water that is known as the meridional overturning circulation (MOC). As a consequence of the MOC northwest Europe enjoys a mild climate for its latitude: however abrupt rearrangement of the Atlantic Circulation has been shown in climate models and in palaeoclimate records to be responsible for a cooling of European climate of between 5-10°C. A principal objective of the RAPID programme is the development of a pre-operational prototype system that will continuously observe the strength and structure of the MOC. An initiative has been formed to fulfill this objective and consists of three interlinked projects:

The entire monitoring array system created by the three projects will be recovered and redeployed annually until 2008 under RAPID funding. From 2008 until 2014 the array will continue to be serviced annually under RAPID-WATCH funding.

The array will be focussed on three regions, the Eastern Boundary (EB), the Mid Atlantic Ridge (MAR) and the Western Boundary (WB). The geographical extent of these regions are as follows:

References

Baehr, J., Hirschi, J., Beismann, J.O. and Marotzke, J. (2004) Monitoring the meridional overturning circulation in the North Atlantic: A model-based array design study. Journal of Marine Research, Volume 62, No 3, pp 283-312.

Baringer, M.O'N. and Larsen, J.C. (2001) Sixteen years of Florida Current transport at 27N Geophysical Research Letters, Volume 28, No 16, pp3179-3182

Bryden, H.L., Johns, W.E. and Saunders, P.M. (2005) Deep Western Boundary Current East of Abaco: Mean structure and transport. Journal of Marine Research, Volume 63, No 1, pp 35-57.

Hirschi, J., Baehr, J., Marotzke J., Stark J., Cunningham S.A. and Beismann J.O. (2003) A monitoring design for the Atlantic meridional overturning circulation. Geophysical Research Letters, Volume 30, No 7, article number 1413 (DOI 10.1029/2002GL016776)


RAPID- Will the Atlantic Thermohaline Circulation Halt? (RAPID-WATCH)

RAPID-WATCH (2007-2014) is a continuation programme of the Natural Environment Research Council's (NERC) Rapid Climate Change (RAPID) programme. It aims to deliver a robust and scientifically credible assessment of the risk to the climate of UK and Europe arising from a rapid change in the Atlantic Meridional Overturning Circulation (MOC). The programme will also assess the need for a long-term observing system that could detect major MOC changes, narrow uncertainty in projections of future change, and possibly be the start of an 'early warning' prediction system.

The effort to design a system to continuously monitor the strength and structure of the North Atlantic MOC is being matched by comparative funding from the US National Science Foundation (NSF) for the existing collaborations started during RAPID for the observational arrays.

Scientific Objectives

This work will be carried out in collaboration with the Hadley Centre in the UK and through international partnerships.

Mooring Arrays

The RAPID-WATCH arrays are the existing 26°N MOC observing system array (RAPIDMOC) and the WAVE array that monitors the Deep Western Boundary Current. The data from these arrays will work towards meeting the first scientific objective.

The RAPIDMOC array consists of moorings focused in three geographical regions (sub-arrays) along 26.5° N: Eastern Boundary, Mid-Atlantic Ridge and Western Boundary. The Western Boundary sub-array has moorings managed by both the UK and US scientists. The other sub-arrays are solely led by the UK scientists. The lead PI is Dr Stuart Cunningham of the National Oceanography Centre, Southampton, UK.

The WAVE array consists of one line of moorings off Halifax, Nova Scotia. The line will be serviced in partnership with the Bedford Institute of Oceanography (BIO), Halifax, Canada. The lead PI is Dr Chris Hughes of the Proudman Oceanographic Laboratory, Liverpool, UK.

All arrays will be serviced (recovered and redeployed) either on an annual or biennial basis using Research Vessels from the UK, US and Canada.

Modelling Projects

The second scientific objective will be addressed through numerical modelling studies designed to answer four questions:


Data Activity or Cruise Information

Cruise

Cruise Name D344
Departure Date 2009-10-21
Arrival Date 2009-11-18
Principal Scientist(s)Stuart A Cunningham (National Oceanography Centre, Southampton)
Ship RRS Discovery

Complete Cruise Metadata Report is available here


Fixed Station Information

Fixed Station Information

Station NameWestern Boundary Array
CategoryOffshore area
Latitude26° 37.50' N
Longitude73° 37.50' W
Water depth below MSL

RAPIDMOC Western Boundary (WB) Array

The Western Boundary Array defines a box in which moorings were deployed at the western side of the North Atlantic as part of the RAPIDMOC project and the collaborative project Meridional Overturning Circulation and Heatflux Array (MOCHA). The box region has latitudinal limits of 26° N to 27.5° N and longitudinal limits of 69.5° W to 77.5° W. Moorings have occupied this region since 2004 and are typically deployed for 6 to 18 months.

Moored data summary

Year Cruise ID Number of moorings Data types (number of instruments)
2004 D278 9 (6 RAPIDMOC, 3 MOCHA) ADCP (2), BPR (8), CM (29), MCTD (52), MMP (1)
2005 KN182_2 11 (6 RAPIDMOC, 5 MOCHA) ADCP (2), BPR (6), CM (27), MCTD (56)
2006 RB06-02, SJ14-06 11 (6 RAPIDMOC, 5 MOCHA) ADCP (1), BPR (3), CM (22), IES (7), MCTD (60)
2007 RB07-01 7 (7 RAPIDMOC) ADCP (1), BPR (4), CM (16), MCTD (47)
2008 SJ08-03 11 (8 RAPIDMOC, 3 MOCHA) ADCP (2), BPR (3), CM (40), MCTD (80)
2009 RB0901, D344, D345 16 (11 RAPIDMOC, 5 MOCHA) ADCP (2), BPR (5), CM (39), MCTD (91), DVS (1)
2010 OC459-1, RB1009 9 (8 RAPIDMOC, 1 MOCHA) ADCP (1), BPR (7), CM (23), MCTD (54)
2011 KN200-4 7 (7 RAPIDMOC, 6 MOCHA) ADCP (2), BPR (7), CM (43), MCTD (86), DVS (1), IES (1)

Cruise data summary

During the cruises to service the moored array, a variety of data types are collected. The table below is a summary of these data. The number of CTD profiles performed on these cruises within the box region defined above is also included. Trans-Atlantic hydrographic CTD sections have also been performed since 2004 and are included in the table.

Cruise ID Cruise description Data types Number of CTD profiles performed within the box region
D277 Initial array deployment DIS, MET, NAV, SADCP, SURF 1
D278 Initial array deployment DIS, MET, NAV, SADCP, SURF 16
D279 Hydrographic section CTD, DIS, LADCP, MET, NAV, SADCP, SURF 31
KN182_2 Array service CTD, DIS, MET, NAV, SADCP, SURF 64
RB0601 Array service CTD, DIS, LADCP, MET, NAV, SADCP, SURF 39
SJ14-06 Array service CTD, DIS, LADCP, MET, NAV, SADCP, SURF 33
RB07-01 Array service CTD, DIS, LADCP, MET, NAV, SADCP, SURF 36
SJ08-03 Array service CTD, DIS, LADCP, MET, NAV, SADCP, SURF 33
RB0901 Array service CTD, DIS, LADCP, MET, NAV, SADCP, SURF 35
D344 Array service CTD, DIS, MET, NAV, SADCP, SURF 3
D345 Array service CTD, DIS, LADCP, MET, NAV, SADCP, SURF 24
OC459-1 Array service CTD, DIS, MET, NAV, SADCP, SURF 9
OC459-2 Western Boundary Hydrographic section CTD, DIS, LADCP, MET, NAV, SADCP, SURF 27
D346 Hydrographic section CTD, DIS, LADCP, MET, NAV, SADCP, SURF 31
RB1009 WB4 service CTD, MET, SURF, NAV 2
KN200-4 Array service CTD, DIS, MET, NAV, SURF 34

Data type ID and description

Data type ID Description
ADCP Acoustic Doppler Current Profiler
BATH Bathymetry
BPR Bottom Pressure Recorder
CM Current Meter
CTD Conductivity-Temperature-Depth profiler
DIS Discrete water bottle samples
DVS Doppler Volume sampler
IES Inverted Echo Sounder
LADCP Lowered Acoustic Doppler Current Profiler
MET Meteorology
MCTD Moored Conductivity-Temperature-Depth sensor
MMP McLane Moored Profiler - profiling CTD and current meter
NAV Navigation
SADCP Shipborne Acoustic Doppler Current Profiler
SURF Sea surface data

Other Series linked to this Fixed Station for this cruise - 1012754 1012778 1093123 1093135 1093147 1093159 1093160

Other Cruises linked to this Fixed Station (with the number of series) - D278 (90) D344 (7) D345 (41) D346 (31) KN182_2 (85) KN200-4 (86) OC459-1 (56) RB0602 (42) RB0701 (58) RB0901 (75) RB1009 (24) RB1201 (55) SJ-08-03 Leg 1 (37) SJ-08-03 Leg 2 (75) SJ-14-06 (62)


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