Metadata Report for BODC Series Reference Number 72587

• 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

The salinity data are of unknown accuracy due to problems with the bench salinometer used for analysis of the calibration bottle samples.

Climatological checks indicate accuracy of the order of +/- 0.02 PSU. Noise of this magnitude occurs in the profile, particularly between the surface and 500 dbar.

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

Bissett-Bermann 9040 Conductivity Temperature and Depth

The basic configuration of the B-B 9040 CTD incorporates pressure, temperature and conductivity sensors which could be logged digitally. This system also made it possible to derive other parameters, such as salinity, depth and sound velocity.

The instrument was versatile and it was possible to attach a dissolved oxygen sensor or to change the CTD housing, allowing it to obtain data from deeper layers in the water column. The accuracy for salinity is ±0.02 ppt , and ±0.02°C for temperature.

This instrument was also known as the Plessey 9040.

RRS John Biscoe Cruise 02 CTD Data Documentation

Introduction

Documentation for the CTD data collected on RRS John Biscoe Cruise 02 (27 February - 15 April 1980) by the British Antarctic Survey, Cambridge, U.K., under the direction of R.B. Heywood.

Data Collection

The instrument used was a Plessey 90/40 CTD. Observed parameters were pressure, temperature and conductivity. All sensors were calibrated before and after the cruise. Up to 12 water bottles were mounted on a Rosette sampler and 4 pairs of reversing thermometers were attached. Water bottles were triggered on the downcast at 10m and at the bottom of the cast, the remainder being fired on the upcast (mainly for chemical samples). Data were collected on the downcast.

Calibration

Reversing thermometers were calibrated at the Deacon Laboratory of the Institute of Oceanographic Sciences. The pressure sensor was compared with a Bourdon gauge which had been calibrated at the National Physical Laboratory. The salinities were determined at the British Antarctic Survey using a Guildline Salinometer. Some time after these data were supplied to BODC the salinometer was found to have been faulty. However the original data were no longer recoverable from the original magnetic tapes to be reprocessed, so this version of the data has been retained. The salinities should be treated with great caution. The accuracy of the temperature data is thought to be ±0.01 °C.

Data Processing

Calibrations were applied and derived quantities were computed from algorithms published by Fofonoff and Millard (1983). Data were then averaged into 1 decibar intervals, centred on unit values. BODC has visually inspected the data and flagged spikes in the data as appropriate. However the salinity data from this cruise are very noisy (±0.02 psu), especially between 0 and 500 decibars.

Data Quality

The salinity data from the CTD have been compared with other measurements made in the same region and also with the Levitus Atlas. Deep water values are within 0.01 ppt of other data, for example that collected on Discovery II (1929-1931) and within 0.02 ppt of Levitus Atlas values.

References

Fofonoff, N.P. and Millard Jr., R.C. 1983.
Algorithms for the computation of fundamental properties of sea water. UNESCO Technical Paper on Marine Science 44

Levitus, S. 1982.
Climatological Atlas of the World Ocean. NOAA Professional Paper No. 13. US Government Printing Office. 173pp

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: