Metadata Report for BODC Series Reference Number 971975


Metadata Summary

Data Description

Data Category CTD or STD cast
Instrument Type
NameCategories
Neil Brown MK3 CTD  CTD; water temperature sensor; salinity sensor; dissolved gas sensors
Instrument Mounting research vessel
Originating Country United Kingdom
Originator Dr Meric Srokosz
Originating Organization James Rennell Centre for Ocean Circulation (now National Oceanography Centre, Southampton)
Processing Status banked
Online delivery of data Download available - Ocean Data View (ODV) format
Project(s) WOCE
UK WOCE
 

Data Identifiers

Originator's Identifier CTD62A11
BODC Series Reference 971975
 

Time Co-ordinates(UT)

Start Time (yyyy-mm-dd hh:mm) 1991-09-13 20:02
End Time (yyyy-mm-dd hh:mm) -
Nominal Cycle Interval 2.0 decibars
 

Spatial Co-ordinates

Latitude 62.28967 N ( 62° 17.4' N )
Longitude 4.95317 W ( 4° 57.2' W )
Positional Uncertainty 0.0 to 0.01 n.miles
Minimum Sensor or Sampling Depth 0.99 m
Maximum Sensor or Sampling Depth 198.97 m
Minimum Sensor or Sampling Height 21.72 m
Maximum Sensor or Sampling Height 219.7 m
Sea Floor Depth 220.7 m
Sea Floor Depth Source DATAHEAD
Sensor or Sampling Distribution Variable common depth - All sensors are grouped effectively at the same depth, but this depth varies significantly during the series
Sensor or Sampling Depth Datum Instantaneous - Depth measured below water line or instantaneous water body surface
Sea Floor Depth Datum Instantaneous - Depth measured below water line or instantaneous water body surface
 

Parameters

BODC CODERankUnitsTitle
POTMCV011Degrees CelsiusPotential temperature of the water body by computation using UNESCO 1983 algorithm
PRESPR011DecibarsPressure (spatial co-ordinate) exerted by the water body by profiling pressure sensor and corrected to read zero at sea level
PSALST011DimensionlessPractical salinity of the water body by CTD and computation using UNESCO 1983 algorithm
SIGTPR011Kilograms per cubic metreSigma-theta of the water body by CTD and computation from salinity and potential temperature using UNESCO algorithm
TEMPST011Degrees CelsiusTemperature of the water body by CTD or STD

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

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

Neil Brown MK3 CTD

The Neil Brown MK3 conductivity-temperature-depth (CTD) profiler consists of an integral unit containing pressure, temperature and conductivity sensors with an optional dissolved oxygen sensor in a pressure-hardened casing. The most widely used variant in the 1980s and 1990s was the MK3B. An upgrade to this, the MK3C, was developed to meet the requirements of the WOCE project.

The MK3C includes a low hysteresis, titanium strain gauge pressure transducer. The transducer temperature is measured separately, allowing correction for the effects of temperature on pressure measurements. The MK3C conductivity cell features a free flow, internal field design that eliminates ducted pumping and is not affected by external metallic objects such as guard cages and external sensors.

Additional optional sensors include pH and a pressure-temperature fluorometer. The instrument is no longer in production, but is supported (repair and calibration) by General Oceanics.

Specifications

These specification apply to the MK3C version.

Pressure Temperature Conductivity
Range

6500 m

3200 m (optional)

-3 to 32°C 1 to 6.5 S cm-1
Accuracy

0.0015% FS

0.03% FS < 1 msec

0.0005°C

0.003°C < 30 msec

0.0001 S cm-1

0.0003 S cm-1 < 30 msec

Further details can be found in the specification sheet.

RRS Charles Darwin 62A CTD Data Documentation

Introduction

CTD profile data are presented from the ERS-1 validation cruise Charles Darwin 62A, as reported by Srokosz et al. (1992). The data collection and calibration procedures have been described by Tokmakian et al. (1992).

Instrumentation and Methodology

Instrumentation Summary

The CTD profiles were taken with a Neil Brown Systems MkIIIb CTD mounted beneath a bottle rosette. The CTD was fitted with a pressure sensor, conductivity cell, platinum resistance thermometer, a dissolved oxygen sensor, an Aquatracka fluorometer, a Sea Tech 25cm path transmissometer and an IOS 10kHz pinger.

Data Acquisition

Lowering rates for the CTD package were generally in the range 0.5-1.0ms-1 but could be up to 1.5ms-1. CTD data were logged at 16 frames per second. The CTD deck unit passes raw data to a dedicated Level A microcomputer where 1 second averages are assembled. During this process the Level A calculates the rate of change of temperature and a median sorting routine detects and removes pressure spikes. These data are sent to the Level B for archival. The data are then passed to a Level C workstation for conversion to Pstar format and calibration.

A total of 27 stations (01 - 29) were occupied. Station 01 was a test dip and station 10 a failure. Station 11 was a repeat of station 10. The reversing thermometer T260 was only used at station 02.

Data Processing

The 1 second data passed to the Level C were converted to Pstar format and initially calibrated with coefficients from laboratory calibrations. The up cast data were extracted for merging with the bottle firing codes, on time, thus the CTD variables were reconciled with the bottle samples. Final calibrations were applied using the sample bottle data.

The data were worked up to WOCE standards by the data originators before being supplied to BODC. The oxygen, fluorometer and transmissometer data cannot be used because of problems with the calibration coefficients supplied by RVS.

BODC Data Processing

No further calibrations were applied to the data received by BODC. BODC were mainly concerned with the screening and banking of the data.

The CTD data were received as 2db averaged pressure sorted down cast data. Parameters were pressure (dbar), temperature (°c), and salinity (psu). The oxygen, fluorescence and attenuance data were ignored.

The data were converted into the BODC internal format (PXF) to allow the use of in-house software tools, notably the graphics editor. During this process all the oxygen, fluorometer and transmissometer data were set null. Spikes in the data were manually flagged 'suspect' by modification of the associated quality control flag. In this way none of the original data values were edited or deleted during quality control. These data from cruise CD62A required little flagging and just a few points were set suspect.

Once screened, the CTD data were loaded into a database under the Oracle relational database management system. The start time stored in the database is the CTD deployment time, and the end time is the time the CTD reached the bottom. The start time is more precisely the start of data logging. Latitude and longitude are the mean positions between the start and end times calculated from the master navigation in the binary merged file.

References

Srokosz, M.A. et al. (1992). RRS Charles Darwin Cruise 62A. Institute of Oceanographic Sciences Deacon Laboratory, Cruise Report No. 229, 49pp.

Tokmakian, R.T. et al. (1992). CTD and XBT collected on ERS-1 validation cruise RRS Charles Darwin Cruise 62A, Iceland-Faeroes region. Institute of Oceanographic Sciences Deacon Laboratory, Report No. 294, 86pp.


Project Information

World Ocean Circulation Experiment (WOCE)

The World Ocean Circulation Experiment (WOCE) was a major international experiment which made measurements and undertook modelling studies of the deep oceans in order to provide a much improved understanding of the role of ocean circulation in changing and ameliorating the Earth's climate.

WOCE had two major goals:


UK WOCE

The UK made a substantial contribution to the international World Ocean Circulation Experiment (WOCE) project by focusing on two important regions:

  1. Southern Ocean - links all the worlds oceans, controlling global climate.
  2. North Atlantic - directly affects the climate of Europe.

A major part of the UK effort was in the Southern Ocean and work included:

In the North Atlantic the UK undertook:

Satellite ocean surface topography, temperature and wind data were merged with in situ observations and models to create a complete description of ocean circulation, eddy motion and the way the ocean is driven by the atmosphere.

The surveys were forerunners to the international Global Ocean Observing System (GOOS). GOOS was later established to monitor annual to decadal changes in ocean circulation and heat storage which are vital in the prediction of climate change.


Data Activity or Cruise Information

Cruise

Cruise Name CD62A
Departure Date 1991-09-06
Arrival Date 1991-09-28
Principal Scientist(s)Meric Srokosz (James Rennell Centre for Ocean Circulation)
Ship RRS Charles Darwin

Complete Cruise Metadata Report is available here


Fixed Station Information

Fixed Station Information

Station NameWOCE-AR18
CategoryOffshore area
Latitude65° 0.00' N
Longitude9° 0.00' W
Water depth below MSL

World Ocean Circulation Experiment (WOCE) Atlantic Area 18 (AR18)

WOCE was a major international experiment which made measurements and undertook modelling studies of the deep oceans in order to provide a much improved understanding of the role of ocean circulation in changing and ameliorating the Earth's climate. WOCE established numerous areas and repeat sections in the Atlantic Ocean as illustrated in the map below.

BODC image

AR18 encompasses the Norwegian Sea basin and stations lie within a box bounded by 69°N, 38°W at the northwest corner and 60°N, 16°E at the southeast corner. The area was occupied between September 1991 to September 1997. A table of all AR18 cruises is presented below:

Cruise Cruise dates Country
Charles Darwin 62A 1991-09-06 to 1991-09-28 UK
Johan Hjort 1092 1992-07-12 to 1992-07-28 Norway
Aranda 1993 1993-08-23 to 1993-09-24 Finland
Johan Hjort 0894 1994-07-23 to 1994-08-16 Norway
Johan Hjort 19941029 1994-10-29 to 1994-11-23 Norway
Bjarni Saemundsson 1495 1995-09-05 to 1995-09-14 Iceland
Aranda 1997 1997-08-05 to 1997-09-25 Finland

Related Fixed Station activities are detailed in Appendix 1


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

Appendix 1: WOCE-AR18

Related series for this Fixed Station are presented in the table below. Further information can be found by following the appropriate links.

If you are interested in these series, please be aware we offer a multiple file download service. Should your credentials be insufficient for automatic download, the service also offers a referral to our Enquiries Officer who may be able to negotiate access.

Series IdentifierData CategoryStart date/timeStart positionCruise
971883CTD or STD cast1991-09-12 06:28:0063.94767 N, 6.201 WRRS Charles Darwin CD62A
971895CTD or STD cast1991-09-12 11:29:0063.9665 N, 5.38917 WRRS Charles Darwin CD62A
971902CTD or STD cast1991-09-12 16:52:0063.95767 N, 4.45267 WRRS Charles Darwin CD62A
971914CTD or STD cast1991-09-12 21:55:0063.96267 N, 3.53583 WRRS Charles Darwin CD62A
971926CTD or STD cast1991-09-13 02:36:0063.63667 N, 3.84733 WRRS Charles Darwin CD62A
971938CTD or STD cast1991-09-13 06:55:0063.31167 N, 4.08617 WRRS Charles Darwin CD62A
971951CTD or STD cast1991-09-13 11:32:0062.983 N, 4.35867 WRRS Charles Darwin CD62A
971963CTD or STD cast1991-09-13 15:51:0062.6465 N, 4.6325 WRRS Charles Darwin CD62A
971987CTD or STD cast1991-09-13 23:13:0062.64433 N, 5.216 WRRS Charles Darwin CD62A
971999CTD or STD cast1991-09-14 02:15:0062.977 N, 5.44533 WRRS Charles Darwin CD62A
972002CTD or STD cast1991-09-14 06:21:0063.3155 N, 5.75783 WRRS Charles Darwin CD62A
972014CTD or STD cast1991-09-14 10:26:0063.63333 N, 6.0055 WRRS Charles Darwin CD62A
972026CTD or STD cast1991-09-19 12:08:0062.265 N, 5.01783 WRRS Charles Darwin CD62A
972038CTD or STD cast1991-09-19 15:52:0062.64833 N, 5.20983 WRRS Charles Darwin CD62A
972051CTD or STD cast1991-09-19 19:20:0062.9755 N, 5.46667 WRRS Charles Darwin CD62A
972063CTD or STD cast1991-09-20 00:02:0063.31067 N, 5.76 WRRS Charles Darwin CD62A
972075CTD or STD cast1991-09-20 04:31:0063.63967 N, 5.99967 WRRS Charles Darwin CD62A
972087CTD or STD cast1991-09-20 13:40:0063.94217 N, 6.2985 WRRS Charles Darwin CD62A
972099CTD or STD cast1991-09-20 18:57:0063.96283 N, 5.38483 WRRS Charles Darwin CD62A
972106CTD or STD cast1991-09-21 06:09:0063.636 N, 3.84417 WRRS Charles Darwin CD62A
972118CTD or STD cast1991-09-21 23:29:0062.97733 N, 4.36467 WRRS Charles Darwin CD62A
972131CTD or STD cast1991-09-22 05:58:0062.64867 N, 4.63083 WRRS Charles Darwin CD62A
972143CTD or STD cast1991-09-22 10:48:0062.289 N, 4.92733 WRRS Charles Darwin CD62A
972155CTD or STD cast1991-09-23 02:37:0062.9705 N, 4.94517 WRRS Charles Darwin CD62A
972167CTD or STD cast1991-09-23 06:25:0063.307 N, 4.93883 WRRS Charles Darwin CD62A
972179CTD or STD cast1991-09-23 10:28:0063.30883 N, 4.1025 WRRS Charles Darwin CD62A