Search the data

Metadata Report for BODC Series Reference Number 747703


Metadata Summary

Data Description

Data Category CTD or STD cast
Instrument Type
NameCategories
Seapoint Turbidity Meter  optical backscatter sensors
Seapoint chlorophyll fluorometer  fluorometers
LI-COR LI-192 PAR sensor  radiometers
Falmouth Scientific Instruments Integrated CTD Profiler  CTD; water temperature sensor; salinity sensor
Instrument Mounting research vessel
Originating Country United Kingdom
Originator Dr Liam Fernand
Originating Organization 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 CO15/04/31
BODC Series Reference 747703
 

Time Co-ordinates(UT)

Start Time (yyyy-mm-dd hh:mm) 2004-10-14 12:31
End Time (yyyy-mm-dd hh:mm) 2004-10-14 12:33
Nominal Cycle Interval 0.1 decibars
 

Spatial Co-ordinates

Latitude 51.52750 N ( 51° 31.7' N )
Longitude 1.02933 E ( 1° 1.8' E )
Positional Uncertainty 0.05 to 0.1 n.miles
Minimum Sensor or Sampling Depth 1.0 m
Maximum Sensor or Sampling Depth 14.0 m
Minimum Sensor or Sampling Height 1.0 m
Maximum Sensor or Sampling Height 14.0 m
Sea Floor Depth 15.0 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
CPHLPS011Milligrams per cubic metreConcentration of chlorophyll-a {chl-a CAS 479-61-8} per unit volume of the water body [particulate >unknown phase] by in-situ chlorophyll fluorometer and calibration against sample data
FVLTWS011VoltsRaw signal (voltage) of instrument output by linear-response chlorophyll fluorometer
IRRDUV011MicroEinsteins per square metre per secondDownwelling vector irradiance as photons of electromagnetic radiation (PAR wavelengths) in the water body by cosine-collector radiometer
LVLTLD011VoltsRaw signal (voltage) of instrument output by cosine-collector downwelling PAR radiometer
NVLTSP011VoltsRaw signal (voltage) of instrument output by SeaPoint turbidity meter
POTMCV011Degrees CelsiusPotential temperature of the water body by computation using UNESCO 1983 algorithm
PPSBZZ011MetresDepth below surface of the water body by unknown instrument and correction to zero at sea level and conversion to depth using unspecified algorithm
PRESPR011DecibarsPressure (spatial coordinate) exerted by the water body by profiling pressure sensor and correction to read zero at sea level
PSALCC011DimensionlessPractical salinity of the water body by CTD and computation using UNESCO 1983 algorithm and calibration against independent measurements
SIGTEQ011Kilograms per cubic metreSigma-theta of the water body by computation from salinity and potential temperature using UNESCO algorithm
SIGTEQST1Kilograms per cubic metreSigma-T of the water body by computation from salinity and temperature using UNESCO algorithm
SVELCT011Metres per secondSound velocity in the water body by CTD and computation from temperature and salinity by unspecified algorithm
TEMPCC011Degrees CelsiusTemperature of the water body by CTD and verification against independent measurements
TSEDBSCL1Milligrams per litreConcentration of suspended particulate material {SPM} per unit volume of the water body [particulate >unknown phase] by in-situ optical backscatter measurement and calibration against sample data

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.

Seapoint Chlorophyll Fluorometer

The Seapoint Chlorophyll Fluorometer (SCF) is a low power instrument for in situ measurements of chlorophyll a. The SCF uses modulated blue LED lamps and a blue excitation filter to excite chlorophyll a. The fluorescent light emitted by the chlorophyll a passes through a red emission filter and is detected by a silicon photodiode. The low level signal is then processed using synchronous demodulation circuitry which generates an output voltage proportional to chlorophyll a concentration. The SCF may be operated with or without a pump.

Sensor specifications, current at August 2006, are given in the table below. More information can be found at the manufacturer's web site.

Sensor Specifications

Power requirements 8 - 20 VDC, 15 mA avg., 27 mA pk.
Output 0 - 5.0 VDC
Output Time Constant 0.1 sec.
Power-up transient period < 1 sec.
Excitation Wavelength 470 nm CWL, 30 nm FWHM
Emission Wavelength 685 nm CWL, 30 nm FWHM
Sensing Volume 340 mm3
Minimum Detectable Level 0.02 µg l-1

  Gain Sensitivity, V µg-1 l-1 Range, µg l-1
Sensitivity/Range 30x
10x
3x
1x
1.0
0.33
0.1
0.033
5
15
50
150

LI-COR LI-192 Underwater Quantum Sensor

The LI-192 Underwater Quantum Sensor is used to measure photosynthetic photon flux density and is cosine corrected. The sensor is often referred to as LI-192SA or LI-192SB (the LI-192SB model was superseded by LI-192SA). One of the main differences is that the LI-192SA model includes a built-in voltage output for interfacing with NexSens iSIC and SDL data loggers.

Sensor specifications, current at January 2012, are given in the table below. More information can be found in the manufacturer's LI-192SA andLI-192SB specification sheets.

Sensor Specifications

(Specifications apply to both models unless otherwise stated)

Absolute Calibration ± 5 % in air traceable to NBS.
Sensitivity Typically 3 µA per 1000 µmol s-1 m-2 for LI-192SB and 4 µA per 1000 µmol s-1 m-2 for LI-192SA in water.
Linearity Maximum deviation of 1 % up to 10,000 µmol s-1 m-2.
Stability < ± 2 % change over a 1 year period.
Response Time 10 µs.
Temperature Dependence ± 0.15 % per °C maximum.
Cosine Correction Optimized for both underwater and atmospheric use.
Azimuth < ± 1 % error over 360 ° at 45 ° elevation.
Detector High stability silicon photovoltaic detector (blue enhanced).
Sensor Housing Corrosion resistant metal with acrylic diffuser for both saltwater and freshwater applications. Waterproof to withstand 800 psi (5500 kPa) (560 meters).

Seapoint Turbidity Meter

The Seapoint Turbidity Meter detects light scattered by particles suspended in water, generating an output voltage proportional to turbidity or suspended solids. Range is selected by two digital lines which can be hard wired or microprocessor controlled, thereby choosing the appropriate range and resolution for measurement of extremely clean to very turbid waters. The offset voltage is within 1 mV of zero and requires no adjustment across gains. The optical design confines the sensing volume to within 5 cm of the sensor allowing near-bottom measurements and minimizing errant reflections in restricted spaces.

Sensor specifications, current at August 2006, are given in the table below.

Sensor Specifications

Power requirements 7 - 20 VDC, 3.5 mA avg., 6 mA pk.
Output 0 - 5.0 VDC
Output Time Constant 0.1 sec.
RMS Noise> < 1 mV
Power-up transient period < 1 sec.
Light Source Wavelength 880 nm
Sensing Distance (from windows) < 5 cm (approx.)
Linearity < 2% deviation 0 - 750 FTU

  Gain Sensitivity (mV FTU-1) Range (FTU)
Sensitivity/Range 100x
20x
5x
1x
200
40
10
2
25
125
500
**

** output is non-linear above 750 FTU.

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

RV CORYSTES: CRUISE 15/04: CTD data document

Sampling strategy

A total of 14 full depth CTD profiles were obtained. CTD were deployed at West Gabbard and at the Warp. CTD profiles were not collected during the transect between the Warp and West Gabbard due to the weather.

For further detail please refer to the cruise report

Instrument Description

Instrumentation and data processing

The CTD used was a Falmouth Scientific Inc with serial number 1351. Samples were collected for salinity analysis (using a Guildline salinometer) to derive a calibration for the instrument conductivity sensor. A pair of digital reversing thermometers were used to compare with the CTD temperature estimates. A CHELSEA fluorometer and SEAPOINT turbidity sensor were used at all CTD stations. A LICOR photosynthetically-active- radiation sensor (with a six-decade log amplifier was fitted to the rosette at all CTD stations. Chlorophyll samples were collected to calibrate the fluorometer and samples for suspended particulate matter analysis were used to calibrate the turbidity sensor.

A list of calibrated parameters and instrumentation used is shown below.

Measurment Parameter Units Instrumentation Calibration
pres Pressure dbar Not listed Corrected from deck measurements
temp Temperature °C Temperature sensor Calibrated December 2004
salinity Salinity n/a Guildline Salinometer Calibrated against bottle samples
turb Turbidity volts Seapoint Turbidity sensor Calibrated against bottle samples
sl Suspended Load mg/L Seapoint Turbidity sensor Used to calibrate turbidity
light Light volts Licor Light sensor (s/n 5672) Used to calculate PAR
fluor Fluorescence volts Seapoint Fluorometer Calibrated against bottle samples

Change of sensors during cruise: None reported.

The data sets were calibrated by CEFAS:

(a) Pressure

During the cruise the 'on deck' CTD pressure immediately prior to lowering the CTD was recorded. These 'on deck' observations have been used to correct recorded CTD pressure as follows:

P(cor) = P(unc) + dP

Station Pctd on deck
2 -0.05
3 -0.05
5 -0.05
6 -0.067
9 -0.083
11 -0.0667
12 -0.1
21 -0.15
27 -0.18
28 -0.14
29 -0.13
31 -0.14
29 -0.13
Mean -0.1

dp = 0.1 was used in the CTD (pressure sensor) calibration

(b) Temperature

The Platinum Resistance Thermometer (PRT) temperature sensor fitted to CTD 1351 was calibrated using PRT's during December 2004, and this was used to correct the CTD temperature :

T(cor) = T(unc) + dT

dT = a*T(unc)*T(unc) + b*T(unc) + c

where

a = 1.42e-5 b = -2.734e-4 c = -1.7166e-3 for s/n 1322

(c) Conductivity

For this cruise it is assumed that the tolerance between salinity (water samples) and CTD (salinity) is accurate to 0.1 plus the manufacturer tolerance of 0.003. Most of the stations for CTD s/n 1351B, 1366B and 1397B are within the required tolerance. All CTD readings not within this tolerance have not been used for any calculations. Salinometer reading takes precedence over the CTD reading.

A least square fit was used to determine appropriate calibration coefficients:

CR(cor) = CR(ctd) [a*T(cor) + b*P(cor) + c]

where T(cor) and P(cor) are the corrected CTD temperature and pressure and

s/n 1322B

a -3.117E-06

b -1.473E-06

c 1.00040132

Using these coefficients the rms difference between water sample (salinometer) and corrected CTD salinity for s/n 1322B is 0.004 (26 values).

d) Suspended Load - Turbidity Sensor Calibration

The Seapoint turbidity sensor was calibrated by comparing recorded voltages with samples collected (during ascent of the CTD) for suspended load analysis

suspended load (mg/l) = a * Turbidity (volts) + b

where

a = 7.99E+00 b = -8.51E+00 R2 = 0.6861 (for stations 2 - 32)

e) Fluorometer - Chlorophyll Calibration

A Seapoint fluorometer (s/n unknown) was fitted to the rosette sampler and used to estimate chlorophyll levels. The sensor was calibrated by comparing recorded voltages with measured chlorophyll of samples collected in niskin bottles as the CTD rosette returned to the surface.

Chlorophyll (ug/l) = a*Fluorometer (volts) + b

a = 81.97 b = -1.131 R2 = 0.815 (for stations 2 - 32)

f) Photosynthetically Active Radiation

The Licor light sensor (s/n 5672) was calibrated according to the LiCor Amplifier and Sensor calibrations which gave overall factors for calculating uE s-1 m-2.

Offset X=3.44824

L.C=0.170237

BODC post-processing and screening

Reformatting

Data for the 14 CTD casts was provided in ASCII format as .cor files. The data files were converted from ASCII format into BODC internal format (QXF). Source file parameters have been mapped to BODC parameter codes (see table below). No unit conversions were necessary.

Originators Parameter Units Description BODC Parameter BOBC Units Comments
Pres dbars Pressure PRESPR01 dbars Calibration by Cefas
Temp deg C Temperature TEMPCC01 deg C Calibration by Cefas
Salinity no units Salinity PSALCC01 no units Calibration by Cefas
Pot deg C Potential Temperature POTMCV01 deg C Derived from temperature readings
SVEL m/sec Sound Velocity SVELCT01 m/sec -
Sig-th kg m-3 Sigma-Theta SIGTPR01 kg m-3 -
Sigma-t kg m-3 Sigma-t SIGTEQST kg m-3 -
Svan 10-8 Specific volume anomaly - 10-8 Not transfered
dynht - Dynamic Hight No data - Not transfered
bvf cph Brunt Wiesler frequency - cph Not transfered
Depth M Depth DEPHFP01 M Calculated from pressure readings
Turb Volts Turbidity NVLTSP01 Volts Raw voltages - uncalibrated
sl mg/L Suspended load TSEDBSCL mg/L Calibrated by Cefas
light Volts - LVLTLD01 Volts Raw voltages - uncalibrated
PAR µE M-2 S-1 Photosynthetically Active Radiation IRRDUV01 µE M-2 S-1 Calibrated by Cefas
Fluor Volts Fluorescence FVLTWS01 Volts Used to calculate chlorophyll
Chl mg/m3 Chlorophyll CPHLPS01 mg/m3 Calibrated by Cefas

Parameters such as Specific Volume Anomaly (SVAN) were not transferred as they are not considered environmental measurements and can be readily reproduced from the other data.

Screening

Reformatted CTD data were visualised using the in-house editor EDSERPLO. EDSERPLO provides a graphical representation of the data so that parameters can be checked for anomolies. All parameters were plotted against depth. Checks include identifying data spikes, gaps in the data and values that lie outside of expected limits for the environment. No data values are deleted. Suspect data are marked by adding an appropriate quality control flag.


Project Information


No Project Information held for the Series

Data Activity or Cruise Information

Cruise

Cruise Name COR15/04
Departure Date 2004-10-13
Arrival Date 2004-10-14
Principal Scientist(s)David Brian Sivyer (Centre for Environment, Fisheries and Aquaculture Science Lowestoft 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