Metadata Report for BODC Series Reference Number 489745

• 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

Falmouth Scientific Integrated CTD (ICTD) Profiler

The FSI ICTD is designed to collect high precision conductivity, temperature and pressure data with self calibrating electronics. This instrument can support five primary sensors (including up to three temperature sensors) and can be coupled with a water bottle sampler. The ICTD is equipped with a titanium housing rated to 7000 m and has a sampling rate of 32 Hz.

Three temperature sensors are available: primary platinum, redundant platinum and exposed thermistor. Any combination of these can be used in the primary channels. The instrument also has multiple RS-232 serial inputs for a variety of sensors including: ADCP, Benthos PSA-916 Altimeter and WetLabs SAFire. There are an additional eight DC input channels that can support virtually any sensor that has a DC output.

Specifications:

*Optional

Further details can be found in the manufacturer's specification sheet.

Corystes 11/95 CTD Data Documentation

Introduction

CTD sensor calibrations for Cruise Corystes 11B/1995 Irish Sea, Stations 44 - 57

Instrumentation and Protocols

For this cruise, the Falmouth Scientific Instruments CTD (s/n 1351) was used. Fourteen CTD profiles were obtained. Water samples were collected for salinity analysis and the measurement of suspended load. No samples were collected for nutrient analysis. The station positions are shown in Fig. 1.

No reversing thermometers, mercury-in-glass or electronic, were used on this cruise.

Water samples were taken at all stations for later analysis. Only three pairs of duplicate samples were collected.

Sensor Calibration for FSI CTD

Pressure

The laboratory calibration of October 1995 was used to correct the pressure sensor.

Ptrue = Pctd +dP

where:

dP = (Pctd * -0.002) + 0.203

Temperature

In the absence of any reversing thermometer data, the laboratory calibrations of the 'fast' and 'slow' sensors in October 1995 were used.

Tcor = Tctd + dT

where:

dT = ax**2 + bx + c

and for the `slow' sensor

a = 0.0001379015
b = -0.0028631233
c = 0.0143711189

and for the `fast' sensor

a = 0.0001378481
b = -0.0026625387
c = 0.0086709023

Salinity

Fig. 2 shows the differences between the water sample salinity as measured with the salinometer and that derived from the CTD before any calibrations have been applied to the latter.

Fig. 3 shows the ratio of CTD conductivity to water sample conductivity after the CTD pressure and temperature have been corrected using the coefficients in 3a and 3b above.

From these data, coefficients have been derived to calibrate the CTD conductivity sensor using a least square fit between the ratio of water sample conductivity to CTD conductivity and the CTD temperature and pressure.

CR(cor) = CR(ctd)*{a*T(cor) + b*P(cor) + c}

where:

T(cor) and P(cor) are the corrected CTD temperature and pressure
a = -0.155474894e-03
b = 0.485560894e-05
c = 0.100145154e+01

RMS salinity difference between water sample salinity and corrected CTD = 0.002 for 27 observations.

Fig. 4 shows the difference between water sample salinity and CTD salinity after calibration of all sensors.

In Fig. 5, the upper histogram shows the differences between water sample salinity and CTD salinity (uncorrected); the lower panel shows the situation for corrected data.

Transmission and Suspended Load

A 25 cm transmissometer (s/n 2300) was used during this cruise. Samples were taken at both surface and bottom for laboratory suspended load determination.

A regression was calculated from these values and the %transmission values recorded by the transmissometer. It was in the form:

suspended load = b*loge(%transmission) + c

where
b = -8.52
c = 39.09

S R Jones March 1996

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: