Metadata Report for BODC Series Reference Number 325426

• 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

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

RV Aranda Cruise 7/1990 CTD Data Documentation

Calibrations

CTD profiles were corrected using calibration coefficients derived from cruise Aranda 7/1990. A summary of the results is presented herein.

Temperature

CTD temperature was corrected by applying the coefficients derived from the laboratory calibration of 21 June 1990:

T(cor) = T(ctd) + dT

where:

dT = c + b*T(ctd) + a*T(ctd)*T(ctd)
a = -0.32614x10^-4
b = -0.613104x10^-3
c = 0.925468x10^-3

Pressure

CTD pressure was corrected by applying the coefficients derived from the laboratory calibration of 21 June 1990:

P(cor) = P(ctd) + dP

where:

dP = a*T(cor) + b*P(ctd) + c
a = 0.10425532
b = 0.36670552x10^-2
c = 0.541245580

Conductivity Ratio

CTD conductivity was corrected by converting water sample salinity to in situ conductivity (from the UNESCO algorithm) and comparing it to CTD conductivity values. The water sample salinity was measured using Guildline bench salinometer. A least squares regression was performed on the corrected data to derive the calibration coefficients a, b and c and the corrected conductivity ratio is:

CR(cor) = CR(ctd) x CR

where:

CR = a*T(cor) + b*P(cor) + c
a = 0.102667575x10^-3
b = -0.238495919x10^-7
c = 0.993272182

The derived P, T and CR calibration coefficients were used to correct the CTD profiles of the cruise.

Data Quality

Station details are shown in the table below. The root mean square (rms) difference between the corrected CTD salinity and water sample salinity was 0.004 for 6 observations. This was found to be acceptable, in view of the errors inherent in the CTD and bench salinometer. Only stations 1 and 2 were used in determining the calibration coefficients.

In correcting the CTD profiles at stations 1, 2 and 3, odd values of CR were deleted from the top 100 m.

The profile of station 3 was very noisy in the first 400 m and, consequently, these were deleted.

General Data Screening carried out by BODC

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 unfeasible values
• Inconsistencies between related information, for example:
  • Times for instrument deployment and for start/end of data series
  • Length of record and the number of data cycles/cycle interval
  • Parameters expected and the parameters actually present in the data cycles
• Originator's comments on meter/mooring performance and data quality

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

Data cycles are inspected using time or depth series plots of all parameters. Currents are additionally inspected using vector scatter plots and time series plots of North and East velocity components. These presentations undergo intrinsic and extrinsic screening to detect infeasible values within the data cycles themselves and inconsistencies as seen when comparing characteristics of 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 data values will not be altered.

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

• Spurious data at the start or end of the record.
• Obvious spikes occurring in periods free from meteorological disturbance.
• A sequence of constant values in consecutive data cycles.

If a large percentage of the data is affected by irregularities then a Problem Report will be written rather than flagging the individual suspect values. Problem Reports are also used to highlight irregularities seen in the graphical data presentations.

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

• Maximum and minimum values of parameters (spikes excluded).
• The occurrence of meteorological events.

This intrinsic and extrinsic 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 making are not introduced.

Project Information

No Project Information held for the Series

Data Activity or Cruise Information

Cruise

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:

SeaDataNet Quality Control Flags

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