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Metadata Report for BODC Series Reference Number 489604


Metadata Summary

Data Description

Data Category CTD or STD cast
Instrument Type
NameCategories
Unknown transmissometer  transmissometers
Falmouth Scientific Instruments Integrated CTD Profiler  CTD; water temperature sensor; salinity sensor
Instrument Mounting research vessel
Originating Country United Kingdom
Originator -
Originating Organization Ministry of Agriculture, Fisheries and Food Lowestoft Fisheries Laboratory (now Centre for Environment, Fisheries and Aquaculture Science Lowestoft Laboratory)
Processing Status banked
Online delivery of data Download available - Ocean Data View (ODV) format
Project(s) -
 

Data Identifiers

Originator's Identifier CO11/95/44
BODC Series Reference 489604
 

Time Co-ordinates(UT)

Start Time (yyyy-mm-dd hh:mm) 1995-11-17 09:55
End Time (yyyy-mm-dd hh:mm) -
Nominal Cycle Interval 1.0 metres
 

Spatial Co-ordinates

Latitude 54.43000 N ( 54° 25.8' N )
Longitude 3.64550 W ( 3° 38.7' W )
Positional Uncertainty Unspecified
Minimum Sensor or Sampling Depth 2.0 m
Maximum Sensor or Sampling Depth 20.8 m
Minimum Sensor or Sampling Height 3.2 m
Maximum Sensor or Sampling Height 22.0 m
Sea Floor Depth 24.0 m
Sea Floor Depth Source -
Sensor or Sampling Distribution Variable common depth - All sensors are grouped effectively at the same depth, but this depth varies significantly during the series
Sensor or Sampling Depth Datum Instantaneous - Depth measured below water line or instantaneous water body surface
Sea Floor Depth Datum Instantaneous - Depth measured below water line or instantaneous water body surface
 

Parameters

BODC CODERankUnitsTitle
ACYCAA011DimensionlessSequence number
ATTNMR011per metreAttenuation (red light wavelength) per unit length of the water body by 20 or 25cm path length transmissometer
PRESPR011DecibarsPressure (spatial coordinate) exerted by the water body by profiling pressure sensor and correction to read zero at sea level
PSALPR011DimensionlessPractical salinity of the water body by conductivity cell and computation using UNESCO 1983 algorithm
TEMPST011Degrees CelsiusTemperature of the water body by CTD or STD

Definition of Rank

  • Rank 1 is a one-dimensional parameter
  • Rank 2 is a two-dimensional parameter
  • Rank 0 is a one-dimensional parameter describing the second dimension of a two-dimensional parameter (e.g. bin depths for moored ADCP data)

Problem Reports

No Problem Report Found in the Database


Data Access Policy

Centre for Environment, Fisheries and Aquaculture Science (Cefas) data access conditions

The Centre for Environment, Fisheries and Aquaculture Science (Cefas) is an Executive Agency of the Department of Environment, Food and Rural Affairs (Defra), formerly the Ministry of Agriculture, Fisheries and Food (MAFF). It was also known previously as the Directorate of Fisheries Research (DFR). This data policy refers to data collected by the organisation under all titles.

  • These data have no specific confidentiality restrictions for academic users. However data are restricted for commercial requests and clearance must be obtained by BODC from Cefas before they are released.
  • 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 acknowledgement.
  • The recommended acknowledgement is: "This study uses data from the Centre for Environment, Fisheries and Aquaculture Science (Cefas), provided by the British Oceanographic Data Centre."

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:

Parameter Conductivity Temperature Pressure
Sensor Inductive cell Platinum thermometer Precision-machined Silicon
Range 0 to 70 mS cm-1 -2 to 35°C Customer specified
Accuracy ±0.002 mS cm-1 0.002°C ±0.01 % full scale
Resolution 0.0001 mS cm-1 0.00005°C 0.0004 % full scale
Response 5.0 cm at 1 ms-1

150 ms Platinum

20 ms Thermistor*

25 ms

*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

BODC image BODC image BODC image BODC image BODC image

Project Information


No Project Information held for the Series

Data Activity or Cruise Information

Cruise

Cruise Name COR11B/95
Departure Date 1995-11-08
Arrival Date 1995-11-20
Principal Scientist(s)Jonathon Mark Rees (Ministry of Agriculture, Fisheries and Food Lowestoft Fisheries Laboratory)
Ship RV Corystes

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:

Flag Description
Blank Unqualified
< Below detection limit
> In excess of quoted value
A Taxonomic flag for affinis (aff.)
B Beginning of CTD Down/Up Cast
C Taxonomic flag for confer (cf.)
D Thermometric depth
E End of CTD Down/Up Cast
G Non-taxonomic biological characteristic uncertainty
H Extrapolated value
I Taxonomic flag for single species (sp.)
K Improbable value - unknown quality control source
L Improbable value - originator's quality control
M Improbable value - BODC quality control
N Null value
O Improbable value - user quality control
P Trace/calm
Q Indeterminate
R Replacement value
S Estimated value
T Interpolated value
U Uncalibrated
W Control value
X Excessive difference

SeaDataNet Quality Control Flags

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

Flag Description
0 no quality control
1 good value
2 probably good value
3 probably bad value
4 bad value
5 changed value
6 value below detection
7 value in excess
8 interpolated value
9 missing value
A value phenomenon uncertain
Q value below limit of quantification