Metadata Report for BODC Series Reference Number 934830

• Metadata Summary

• Problem Reports

• Data Access Policy

• Narrative Documents

• Project Information

• Data Activity or Cruise Information

• Fixed Station Information

• BODC Quality Flags

• SeaDataNet Quality Flags

Metadata Summary

Problem Reports

No Problem Report Found in the Database

Data Access Policy

SIMORC data access conditions

The data collated and held at BODC on behalf of the SIMORC project are restricted. However, the data will be available to download from the Official SIMORC Website, as part of the project protocol. The data set will initially include data from the oil companies TOTAL, Shell and BP.

Narrative Documents

Instrument description

Valeport 600 MKIII CTD

The Model 600 MKIII measures Conductivity, Temperature and Pressure parameters and has both time and depth increment based sampling. From these measurements Salinity, Density and Speed of Sound are calculated and displayed or recorded.

Specifications

Temperature

Thermistor range: -5 to 35 °C ; precision: +/- 0.1 °C

Conductivity

Inductive coils range: 0.1 to 60 mS.cm^-1; precision: +/- 0.05 mS.cm^-1

Pressure

Strain gauge range: 50,100, 500,1000 or 2000 dBar; precision: +/-0.5%

Manufacturer specifications can be found here

Valeport CTD 600

Background

The Valeport CTD 600 is designed for Continental Shelf operation and permits the accurate measurement of seawater Conductivity and Temperature against a Depth profile. The results obtained are applicable to many fields of scientific research. The meter is particularly suited to the obtaining of Temperature and Salinity profiles for the computation of the Speed of Sound through water, as required for the calibration of survey echo sounders and acoustic navigation systems.

More information may be found:

Click here for an Oceanscan instrument description

Click here for a pdf stored by BODC.

Parameters

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:

• Irregularities such as infeasible values
• Inconsistencies between related information. For example:
  • Deepest CTD data cycle is significantly greater than the depth of the sea floor.
  • Times of the cruise and the start/end of the data series.
  • Length of the record, number of data cycles, cycle interval, clock error and the period over which data were collected.
  • Parameters stated as measured and the parameters actually present in the data series.
• Originator's comments on instrument/sampling device performance and data quality.

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:

• Spurious data at the start or end of the record where the instrument was recording in air
• Obvious spikes occurring in the data due electrical problems
• Constant, or near-constant, data channels

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:

• Data points with values outside the expected range for the parameter, as defined by the BODC parameter usage vocabulary.

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:

• Maximum and minimum values of parameters (spikes excluded).
• Anomalous readings due to the CTD package being bounced through temperature and/or salinity gradients.

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.

BODC Processing

The originator provided a Comma Separated Values format file. This series was reformatted to the internal QXF format using BODC transfer function 422. The following table shows how the variables within the file were mapped to the appropriate BODC parameter codes:

Datacycles from the up cast were deleted as only the down cast was transferred.

Following transfer to QXF, the data were screened using BODC's in-house visualisation software, EDSERPLO. Any data considered as suspect were flagged 'M'.

Project Information

System of Industry Metocean data for the Offshore and Research Communities (SIMORC)

The EU-funded SIMORC project is a collaborative effort between MARIS (Netherlands), BODC (UK), the International Association of Oil and Gas Producers (OGP) and IOC-IODE to provide a harmonised and quality controlled metocean data set from data collected by oil and gas producers, accessible through the SIMORC protocol.

Data Activity or Cruise Information

Cruise

Complete Cruise Metadata Report is available here

Fixed Station Information

Fixed Station Information

SIMORC: TOTAL Nigeria OML100 Fixed Station Document

5 CTD casts were taken from 07/01/2001 to 18/07/2002 at this site.

The nominal position of the instrument is 3.877585° N; 7.918625° E with a water depth of 100 m.

CTD casts were done on behalf of TOTAL from Nigeria OML100 fixed station as follows:

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:

SeaDataNet Quality Control Flags

The following single character qualifying flags may be associated with one or more individual parameters with a data cycle:

Appendix 1: Nigeria OML100

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.