Metadata Report for BODC Series Reference Number 62741

• 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 Prince Madog Cruise DW7 CTD Data Documentation

Introduction

Documentation for the CTD data collected on RV Prince Madog Cruise DW7 (March 1978) by the School of Ocean Sciences, University College of North Wales, Menai Bridge, Gwynedd, U.K., under the direction of Steve Czitrom.

Instrumentation

The instrument used was the NIO temperature-salinity (T-S) probe because the Plessey model 9400 CTD system was not operational during this cruise. The T-S probe sampled the water column at 1 metre intervals. This instrument has accuracies of ±0.05ppt and ±0.1°C in the salinity and temperature measurements.

Calibrations and Data Quality

Temperature and Salinity

A hydrocast was performed after every second T-S probe station for salinity and temperature sensor calibration checks. Surface, mid-depth and bottom salinity and temperature samples were taken with NIO bottles after the T-S probe was back on deck. Each bottle carried 2 protected reversing thermometers and readings were made after equilibration to ambient temperature. Salinity was determined from samples drawn from the bottles using a Bissett Berman model 6230 salinometer.

The T-S probe temperature sensor calibration was checked using corrected reversing thermometer measurements while salinity sensor calibrations were checked using in-situ salinities derived from the NIO bottles.

A linear regression was carried out using the results from the NIO bottles and the T-S probe data. T-S probe salinity and temperature records were chosen from the profiles so that the T-S probe depth measurement was close to the depth of the hydrocast sample. Measurements taken near strong vertical temperature or salinity gradients were not used in the regressions to prevent errors arising from internal waves, or inaccuracies in the determination of depth.

Fit of T-S probe data to NIO bottle sample values

The mean difference (bottle - T-S) averaged over this cruise and some measurements made during cruise DW8 with the T-S probe gives a value of -0.039°C for the temperature sensor. The temperature calibrations were such that adding this value to all the temperature measurements was a sufficient calibration. The accuracy ofthe temperature sensor appeared to be slightly better than that quoted by the manufacturers and good enough to register the temperature differences encountered at stations in Liverpool Bay. The salinity regressions showed weaker agreement between the probe and the NIO bottles data and the observed salinities were calibrated using the slope and intercept shown above. The accuracy of the salinity sensor appeared to be slightly lower than that quoted by the manufacturers but still good enough to register the salinity differences in Liverpool Bay.

Reference

Czitrom, S. (1983).
Density stratification and associated front in Liverpool Bay. PhD thesis, University of Wales.

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: