Metadata Report for BODC Series Reference Number 1113549
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
Data Description |
|||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|
|||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Data Identifiers |
|||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|
|||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Time Co-ordinates(UT) |
|||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|
|||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Spatial Co-ordinates | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|
|||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Parameters |
|||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|
|||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|
Problem Reports
No Problem Report Found in the Database
James Cook Cruise JC079 AMT22 CTD Data Quality Document
Temperature, salinity, potential temperature and sigma-theta: Entrainment features were visible in a number of casts, both in the frame mounted (primary) and vane mounted (secondary channels). These features were apparent throughout the thermocline/pycnocline and continued down to approximately 200 dbar. The level of entrainment can be indicated by a variation between data points of 0.2 °C in the temperature, of 0.02-0.03 in the salinity and 0.1 kg m-3 in sigma-theta. The vane mounted sensors should theoretically be of better quality than the frame mounted sensors as they are held outside the water mass being carried down within the CTD frame structure, however there was a lot of spiking with spurious data that was not present on the primary channels. Therefore the primary temperature, salinity and density were retained for banking in the NODB, while secondary channels were discarded.
Chlorophyll: In circumstances where data were collected at pressures > 200 dbar, negative concentrations were frequently visible. These were flagged as anomalous. These resulted from the chlorophyll calibration being optimised for the euphotic zone, in particular the fluorescence/chlorophyll maximum.
Dissolved oxygen concentration and oxygen saturation: Cast 63 showed a step in the values and these were flagged suspect in the profile below this point. Overall profiles appear good.
Attenuance and transmissance: As with some of the other channels there were a few spikes that were flagged suspect. Cast 65 (down and up casts) appeared noisy in the surface. Overall the profiles appear of good quality.
Down and up-welling PAR irradiance: Optics casts were taken pre-dawn and at solar noon. Therefore, for almost half the casts, the PAR values are negligible as they were recorded in the dark.
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
Sea-Bird Dissolved Oxygen Sensor SBE 43 and SBE 43F
The SBE 43 is a dissolved oxygen sensor designed for marine applications. It incorporates a high-performance Clark polarographic membrane with a pump that continuously plumbs water through it, preventing algal growth and the development of anoxic conditions when the sensor is taking measurements.
Two configurations are available: SBE 43 produces a voltage output and can be incorporated with any Sea-Bird CTD that accepts input from a 0-5 volt auxiliary sensor, while the SBE 43F produces a frequency output and can be integrated with an SBE 52-MP (Moored Profiler CTD) or used for OEM applications. The specifications below are common to both.
Specifications
Housing | Plastic or titanium |
Membrane | 0.5 mil- fast response, typical for profile applications 1 mil- slower response, typical for moored applications |
Depth rating | 600 m (plastic) or 7000 m (titanium) 10500 m titanium housing available on request |
Measurement range | 120% of surface saturation |
Initial accuracy | 2% of saturation |
Typical stability | 0.5% per 1000 h |
Further details can be found in the manufacturer's specification sheet.
RRS James Cook Cruise JC079 AMT22 CTD Instrumentation
The CTD unit was a Sea-Bird Electronics 911plus system, with dissolved oxygen sensor. The CTD was fitted with an altimeter, up and downwelling PAR sensors, two BB-RTD sensors (one red light and one green light), transmissometer and a fluorometer as auxilliary sensors. All instruments were attached to a 24 position stainless steel Sea-Bird SBE 32 carousel. The table below lists more detailed information about the various sensors.
Sensor | Model | Serial Number | Calibration Date | Comments |
---|---|---|---|---|
Sea-Bird deck unit | 11plus | n/a | - | - |
Sea-Bird underwater unit | 9plus | 0943 | - | - |
Pressure transducer | Paroscientific 410K-134 Digiquartz temperature compensated pressure sensor | 110557 | 2012-05-29 | - |
Conductivity sensor 1 | SBE 4C | 2571 | 2012-08-21 | - |
Conductivity sensor 2 | SBE 4C | 3054 | 2012-08-31 | - |
Temperature sensor 1 | SBE 3P | 2919 | 2012-09-11 | - |
Temperature sensor 2 | SBE 3P | 4151 | 2012-09-13 | - |
Dissolved oxygen | SBE 43 | 0363 | 2012-01-26 | Voltage 0 for casts 1-58. |
Dissolved oxygen | SBE 43 | 2055 | 2012-06-27 | Voltage 0 for casts 59-74. |
Scattering meter | WetLabs BBRTD - red light (700 nm wavelength) | BBRTD-849 | 2011-03-19 | Voltage 1 for casts 1-15 and 17-58. Voltage 2 for cast 16. Voltage 3 for casts 59-74. |
Scattering meter | WetLabs BBRTD - green light (532 nm wavelength) | BBRTD-949 | 2012-03-08 | Voltage 2 for casts 1-15 and 17-58. Voltage 1 for cast 16. |
Altimeter | - | 112522 | - | Voltage 3 for casts 1 to 58. |
Transmissometer | WetLabs C-star - 0.25 m path red light | CST-1426DR | 2011-06-22 | Voltage 4 |
Fluorometer | Chelsea AQUA tracka MkIII | 088195 | 2012-08-21 | Voltage 5 |
PAR sensor - upwelling irradiance | Chelsea 2-pi PAR sensor | 05 | 2011-06-14 | Voltage 6 |
PAR sensor - downwelling irradiance | Chelsea 2-pi PAR sensor | 01 | 2011-06-14 | Voltage 7 |
Change of sensors during cruise: The SBE43 oxygen sensor was changed from cast 59 until the end of the cruise. The backscatter sensors were switched for cast 16 and then swiched back for cast 17. The altimeter on voltage 3 was removed from cast 59 and the backscatter sensor moved from voltage 1 to voltage 3 for the rest of the cruise.
Sampling device
Rosette sampling system equipped with 24 x 20 l sampling bottles (manufactured by Ocean Test Equipment Inc.).
Sea-Bird Electronics SBE 911 and SBE 917 series CTD profilers
The SBE 911 and SBE 917 series of conductivity-temperature-depth (CTD) units are used to collect hydrographic profiles, including temperature, conductivity and pressure as standard. Each profiler consists of an underwater unit and deck unit or SEARAM. Auxiliary sensors, such as fluorometers, dissolved oxygen sensors and transmissometers, and carousel water samplers are commonly added to the underwater unit.
Underwater unit
The CTD underwater unit (SBE 9 or SBE 9 plus) comprises a protective cage (usually with a carousel water sampler), including a main pressure housing containing power supplies, acquisition electronics, telemetry circuitry, and a suite of modular sensors. The original SBE 9 incorporated Sea-Bird's standard modular SBE 3 temperature sensor and SBE 4 conductivity sensor, and a Paroscientific Digiquartz pressure sensor. The conductivity cell was connected to a pump-fed plastic tubing circuit that could include auxiliary sensors. Each SBE 9 unit was custom built to individual specification. The SBE 9 was replaced in 1997 by an off-the-shelf version, termed the SBE 9 plus, that incorporated the SBE 3 plus (or SBE 3P) temperature sensor, SBE 4C conductivity sensor and a Paroscientific Digiquartz pressure sensor. Sensors could be connected to a pump-fed plastic tubing circuit or stand-alone.
Temperature, conductivity and pressure sensors
The conductivity, temperature, and pressure sensors supplied with Sea-Bird CTD systems have outputs in the form of variable frequencies, which are measured using high-speed parallel counters. The resulting count totals are converted to numeric representations of the original frequencies, which bear a direct relationship to temperature, conductivity or pressure. Sampling frequencies for these sensors are typically set at 24 Hz.
The temperature sensing element is a glass-coated thermistor bead, pressure-protected inside a stainless steel tube, while the conductivity sensing element is a cylindrical, flow-through, borosilicate glass cell with three internal platinum electrodes. Thermistor resistance or conductivity cell resistance, respectively, is the controlling element in an optimized Wien Bridge oscillator circuit, which produces a frequency output that can be converted to a temperature or conductivity reading. These sensors are available with depth ratings of 6800 m (aluminium housing) or 10500 m (titanium housing). The Paroscientific Digiquartz pressure sensor comprises a quartz crystal resonator that responds to pressure-induced stress, and temperature is measured for thermal compensation of the calculated pressure.
Additional sensors
Optional sensors for dissolved oxygen, pH, light transmission, fluorescence and others do not require the very high levels of resolution needed in the primary CTD channels, nor do these sensors generally offer variable frequency outputs. Accordingly, signals from the auxiliary sensors are acquired using a conventional voltage-input multiplexed A/D converter (optional). Some Sea-Bird CTDs use a strain gauge pressure sensor (Senso-Metrics) in which case their pressure output data is in the same form as that from the auxiliary sensors as described above.
Deck unit or SEARAM
Each underwater unit is connected to a power supply and data logging system: the SBE 11 (or SBE 11 plus) deck unit allows real-time interfacing between the deck and the underwater unit via a conductive wire, while the submersible SBE 17 (or SBE 17 plus) SEARAM plugs directly into the underwater unit and data are downloaded on recovery of the CTD. The combination of SBE 9 and SBE 17 or SBE 11 are termed SBE 917 or SBE 911, respectively, while the combinations of SBE 9 plus and SBE 17 plus or SBE 11 plus are termed SBE 917 plus or SBE 911 plus.
Specifications
Specifications for the SBE 9 plus underwater unit are listed below:
Parameter | Range | Initial accuracy | Resolution at 24 Hz | Response time |
---|---|---|---|---|
Temperature | -5 to 35°C | 0.001°C | 0.0002°C | 0.065 sec |
Conductivity | 0 to 7 S m-1 | 0.0003 S m-1 | 0.00004 S m-1 | 0.065 sec (pumped) |
Pressure | 0 to full scale (1400, 2000, 4200, 6800 or 10500 m) | 0.015% of full scale | 0.001% of full scale | 0.015 sec |
Further details can be found in the manufacturer's specification sheet.
Chelsea Technologies Group Aquatracka MKIII fluorometer
The Chelsea Technologies Group Aquatracka MKIII is a logarithmic response fluorometer. Filters are available to enable the instrument to measure chlorophyll, rhodamine, fluorescein and turbidity.
It uses a pulsed (5.5 Hz) xenon light source discharging along two signal paths to eliminate variations in the flashlamp intensity. The reference path measures the intensity of the light source whilst the signal path measures the intensity of the light emitted from the specimen under test. The reference signal and the emitted light signals are then applied to a ratiometric circuit. In this circuit, the ratio of returned signal to reference signal is computed and scaled logarithmically to achieve a wide dynamic range. The logarithmic conversion accuracy is maintained at better than one percent of the reading over the full output range of the instrument.
Two variants of the instrument are available, both manufactured in titanium, capable of operating in depths from shallow water down to 2000 m and 6000 m respectively. The optical characteristics of the instrument in its different detection modes are visible below:
Excitation | Chlorophyll a | Rhodamine | Fluorescein | Turbidity |
---|---|---|---|---|
Wavelength (nm) | 430 | 500 | 485 | 440* |
Bandwidth (nm) | 105 | 70 | 22 | 80* |
Emission | Chlorophyll a | Rhodamine | Fluorescein | Turbidity |
Wavelength (nm) | 685 | 590 | 530 | 440* |
Bandwidth (nm) | 30 | 45 | 30 | 80* |
* The wavelengths for the turbidity filters are customer selectable but must be in the range 400 to 700 nm. The same wavelength is used in the excitation path and the emission path.
The instrument measures chlorophyll a, rhodamine and fluorescein with a concentration range of 0.01 µg l-1 to 100 µg l-1. The concentration range for turbidity is 0.01 to 100 FTU (other wavelengths are available on request).
The instrument accuracy is ± 0.02 µg l-1 (or ± 3% of the reading, whichever is greater) for chlorophyll a, rhodamine and fluorescein. The accuracy for turbidity, over a 0 - 10 FTU range, is ± 0.02 FTU (or ± 3% of the reading, whichever is greater).
Further details are available from the Aquatracka MKIII specification sheet.
Chelsea Technologies Photosynthetically Active Radiation (PAR) Irradiance Sensor
This sensor was originally designed to assist the study of marine photosynthesis. With the use of logarithmic amplication, the sensor covers a range of 6 orders of magnitude, which avoids setting up the sensor range for the expected signal level for different ambient conditions.
The sensor consists of a hollow PTFE 2-pi collector supported by a clear acetal dome diverting light to a filter and photodiode from which a cosine response is obtained. The sensor can be used in moorings, profiling or deployed in towed vehicles and can measure both upwelling and downwelling light.
Specifications
Operation depth | 1000 m |
Range | 2000 to 0.002 µE m-2 s-1 |
Angular Detection Range | ± 130° from normal incidence |
Relative Spectral Sensitivity | flat to ± 3% from 450 to 700 nm down 8% of 400 nm and 36% at 350 nm |
Further details can be found in the manufacturer's specification sheet.
Paroscientific Absolute Pressure Transducers Series 3000 and 4000
Paroscientific Series 3000 and 4000 pressure transducers use a Digiquartz pressure sensor to provide high accuracy and precision data. The sensor comprises a quartz crystal resonator that responds to pressure-induced stress, and temperature is measured for thermal compensation of the calculated pressure.
The 3000 series of transducers includes one model, the 31K-101, whereas the 4000 series includes several models, listed in the table below. All transducers exhibit repeatability of better than ±0.01% full pressure scale, hysteresis of better than ±0.02% full scale and acceleration sensitivity of ±0.008% full scale /g (three axis average). Pressure resolution is better than 0.0001% and accuracy is typically 0.01% over a broad range of temperatures.
Differences between the models lie in their pressure and operating temperature ranges, as detailed below:
Model | Max. pressure (psia) | Max. pressure (MPa) | Temperature range (°C) |
---|---|---|---|
31K-101 | 1000 | 6.9 | -54 to 107 |
42K-101 | 2000 | 13.8 | 0 to 125 |
43K-101 | 3000 | 20.7 | 0 to 125 |
46K-101 | 6000 | 41.4 | 0 to 125 |
410K-101 | 10000 | 68.9 | 0 to 125 |
415K-101 | 15000 | 103 | 0 to 50 |
420K-101 | 20000 | 138 | 0 to 50 |
430K-101 | 30000 | 207 | 0 to 50 |
440K-101 | 40000 | 276 | 0 to 50 |
Further details can be found in the manufacturer's specification sheet.
WETLabs C-Star transmissometer
This instrument is designed to measure beam transmittance by submersion or with an optional flow tube for pumped applications. It can be used in profiles, moorings or as part of an underway system.
Two models are available, a 25 cm pathlength, which can be built in aluminum or co-polymer, and a 10 cm pathlength with a plastic housing. Both have an analog output, but a digital model is also available.
This instrument has been updated to provide a high resolution RS232 data output, while maintaining the same design and characteristics.
Specifications
Pathlength | 10 or 25 cm |
Wavelength | 370, 470, 530 or 660 nm |
Bandwidth | ~ 20 nm for wavelengths of 470, 530 and 660 nm ~ 10 to 12 nm for a wavelength of 370 nm |
Temperature error | 0.02 % full scale °C-1 |
Temperature range | 0 to 30°C |
Rated depth | 600 m (plastic housing) 6000 m (aluminum housing) |
Further details are available in the manufacturer's specification sheet or user guide.
RRS James Cook Cruise JC079 AMT22 CTD Processing
Sampling strategy
All casts were conventional profiling casts with water sampling. A stainless steel (SS) CTD system was used. The frame was normally deployed pre-dawn and at solar noon each day.
A total of 73 out of 74 CTD casts were completed for water bottle sampling during the cruise. Cast 01 was cancelled due to a termination problem at the bottom of the downcast before any bottles could be fired. There was a problem during cast 65 where communication was lost for part of the downcast.
BODC Cruise processing
CTD casts were recorded using the Sea-Bird data collection software Seasave-Win32. The software outputs were then processed following the BODC recommended guidelines using SBE Data Processing-Win32 v7.20g; the processing routines are named after each stage in brackets < >. The software applied the calibrations as appropriate through the instrument configuration file to the data in engineering units output by the CTD hardware.
An ascii file (CNV) containing the 24 Hz data for up and down casts was generated from the binary Sea-Bird files for each cast <DatCnv>. Files were created for each cast containing the mean values of all the variables at the bottle firing events <Bottle Summary>. Using the CNV files processing routines were applied to remove pressure spikes <WildEdit>, the oxygen sensor was then shifted relative to the pressure by 2 seconds, to compensate for the lag in the sensor response time <AlignCTD> and the effect of thermal 'inertia' on the conductivity cells was removed <CellTM>. The surface soak was identified for each cast, removed and LoopEdit run. Salinity and oxygen concentration were re-derived and density (sigma-theta) were derived <Derive> after the corrections for sensor lag and thermal 'inertia' had been applied. The CTD files produced from Sea-Bird processing were converted from 24 Hz ascii files into 2 Hz ascii files of the complete cast (down and upcasts) with all channels for archive at BODC and also to 1 dbar downcast files for calibration and visualisation onboard <BinAverage>. The initial salinity and oxygen channels produced at the DatCnv stage, along with the conductivity, voltage and altimeter channels were removed from the 1 dbar downcast files <Strip>.
The Sea-Bird 1 dbar downcast files were converted from the Sea-Bird CNV format to the tab delimited ODV format using the mapping described below:
Parameter Name in Sea-Bird CNV | Units | Parameter Name in ODV file | Units | Comments |
---|---|---|---|---|
prDM: Pressure, Digiquartz | dbar | Pressure | dbar | - |
t090C: Temperature | ITS-90, °C | Temperature_1 | ITS-90, °C | - |
t190C: Temperature, 2 | ITS-90, °C | Temperature_2 | ITS-90, °C | - |
flC: Fluorescence, Chelsea Aqua 3 Chl Con | µg l-l | Fluorometer_notional_calibration | mg m-3 | Units equivalent. No conversion applied. |
par: PAR/Irradiance, Biospherical/Licor | W m-2 | PAR_up | W m-2 | - |
par1: PAR/Irradiance, Biospherical/Licor, 2 | W m-2 | PAR_down | W m-2 | - |
turbWETbb0: Turbidity, WET Labs ECO BB | m-1 sr-1 | Backscatter@700nm | m-1 sr-1 | Provisional calibration applied during the cruise. Final calibration to be applied post cruise and data supplied as a separate series. |
turbWETbb1: Turbidity, WET Labs ECO BB, 2 | m-1 sr-1 | Backscatter@532nm | m-1 sr-1 | Provisional calibration applied during the cruise. Final calibration to be applied post cruise and data supplied as a separate series. |
xmiss: Beam Transmission, Chelsea/Seatech/WET Labs CStar | % | Beam transmission | % | - |
bat: Beam Attenuation, Chelsea/Seatech/WET Labs CStar | m-1 | Beam attenuance | m-1 | - |
sal00: Salinity, Practical | PSU | Salinity_1_SBEcal | PSU | - |
sal11: Salinity, Practical, 2 | PSU | Salinity_2_SBEcal | PSU | - |
sbeox0ML/L: Oxygen, SBE 43 | ml l-1 | Oxy conc ml/l | ml l-1 | - |
sbeox0Mg/L: Oxygen, SBE 43 | mg l-1 | Oxy conc mg/l | mg l-1 | - |
sigma-é00: Density | kg m-3 | Density(sigma-theta)_1 | kg m-3 | - |
sigma-é11: Density, 2 | kg m-3 | Density(sigma-theta)_2 | kg m-3 | - |
Calibrated salinity, oxygen and fluorometer channels were then added to the profiles using calibration equations derived from the bottle file data compared against discrete samples collected from the CTD water bottles on each cast.
Field Calibrations
-
Pressure
No adjustments were made to the values resulting from application of manufacturer's coefficients during the initial processing.
-
Temperature
Temperature readings from the two temperature sensors were almost identical outside of entrainment features and no other independent measurements of better quality were available. No further correction was therefore applied to the data.
-
Salinity
The salinity data were calibrated by comparing the sensor readings from the up-cast at the point when the bottles were fired with the discrete salinity data measured using the bench salinometer on water samples collected from fired bottles. The samples collected were from four depths for each cast. Offsets were generated between the salinometer and CTD sensor values and plotted against cast and salinometer values. The linear regressions from the offset against bench salinometer data were significant for both sensors (sensor 1, p = 0.006; sensor 2, p = 0.026).
Calibration N R2 Salinity_1_calibrated = 0.9992 * Salinity_1_SBEcal + 0.0274 177 0.037 Salinity_2_calibrated = 0.9993 * Salinity_2_SBEcal + 0.0265 173 0.023 The calibration reduction to the RMS residual (sensor 1: uncalibrated = 0.0055, calibrated = 0.0054; sensor 2: uncalibrated = 0.0059, calibrated = 0.0058) although small, indicated an improved match to the bench salinometer sample dataset after calibration.
-
Dissolved oxygen
The oxygen sensors were calibrated by comparing the SBE43 sensor readings from the CTD up-cast at the point when the bottles were fired with the dissolved oxygen concentrations from Winkler titrations on water samples collected from the fired bottles. The samples collected were from a range of depths on a number of casts throughout the cruise. The linear regressions from the offset (Winkler titration data - SBE43 data) against Winkler titration data were significant for casts 1-58 (p < 0.001) but not for the sensor deployed from cast 59 (p = 0.245).
Casts Calibration (in ml l-1) N R2 1-58 Oxygen concentration calibrated = 1.0782 * Oxygen conc ml + 0.0284 168 0.517 59-74 Oxygen concentration calibrated = Oxygen conc ml + 0.3531 67 0.006 The reduction in the RMS residual (uncalibrated = 0.369, calibrated = 0.122) indicated an improved match to the Winkler titration dataset after calibration.
-
Fluorescence
The CTD deployed Chelsea AQUAtracka MkIII fluorometer was calibrated against extracted chlorophyll-a measurements made on seawater collected by Niskin bottles on each cast. Samples of seawater from CTD niskin bottles were collected to calibrate the CTD fluorometer with the analytical method following Welschmeyer (1994). Samples were collected at 73 stations from an average of 9 depths including light depths from 97, 55, 33, 14, 7, 1 and 0.1%. Each sample of 250 ml was filtered through 47 mm 0.2 µm polycarbonate filters. The filters were then placed in a vial with 10 ml 90% acetone and left in a freezer for 24 hours. The samples were then analysed on a pre-calibrated Turner Designs Trilogy fluorometer with a non-acidified chl module (CHL NA #046) fitted. The calibration was checked against dilutions of pure chlorophyll stock during the cruise and no modifications to the calibration were necessary.
The Chelsea AQUAtracka MkIII fluorometer attached to the CTD rig operated without problem. The sample calibrations were applied on a cast by cast basis.
References
Welschmeyer N.A., 1994. Fluorometric analysis of chlorophyll-a in the presence of chlorophyll-b and phaeopigments. Limnology and Oceanography, 39(8), 1985-1992.
Cast Calibration (in mg m-3) N R2 1 No samples collected - - 2 Fluorometer_sample_calibration = 1.8654 * Fluorometer_notional_calibration - 0.0448 8 0.978 3 Fluorometer_sample_calibration = 1.3096 * Fluorometer_notional_calibration - 0.0231 8 0.901 4 Fluorometer_sample_calibration = 3.1427 * Fluorometer_notional_calibration - 0.0814 9 0.955 5 Fluorometer_sample_calibration = 3.9604 * Fluorometer_notional_calibration - 0.0658 9 0.992 6 Fluorometer_sample_calibration = 3.2744 * Fluorometer_notional_calibration - 0.1405 9 0.995 7 Fluorometer_sample_calibration = 2.8944 * Fluorometer_notional_calibration - 0.0684 8 0.994 8 Fluorometer_sample_calibration = 2.4637 * Fluorometer_notional_calibration + 0.0986 9 0.938 9 Fluorometer_sample_calibration = 2.8051 * Fluorometer_notional_calibration + 0.0399 9 0.979 10 Fluorometer_sample_calibration = 4.2481 * Fluorometer_notional_calibration - 0.0447 9 0.984 11 Fluorometer_sample_calibration = 4.1877 * Fluorometer_notional_calibration - 0.0143 9 0.996 12 Fluorometer_sample_calibration = 5.8039 * Fluorometer_notional_calibration - 0.1527 9 0.991 13 Fluorometer_sample_calibration = 4.2159 * Fluorometer_notional_calibration - 0.0561 9 0.993 14 Fluorometer_sample_calibration = 6.0241 * Fluorometer_notional_calibration - 0.1681 9 0.993 15 Fluorometer_sample_calibration = 4.5809 * Fluorometer_notional_calibration - 0.0605 9 0.999 16 Fluorometer_sample_calibration = 7.2099 * Fluorometer_notional_calibration - 0.1334 9 0.989 17 Fluorometer_sample_calibration = 5.8140 * Fluorometer_notional_calibration - 0.1099 9 0.998 18 Fluorometer_sample_calibration = 6.2618 * Fluorometer_notional_calibration - 0.1572 9 0.990 19 Fluorometer_sample_calibration = 7.2993 * Fluorometer_notional_calibration - 0.1599 9 0.997 20 Fluorometer_sample_calibration = 7.8125 * Fluorometer_notional_calibration - 0.2719 9 0.997 21 Fluorometer_sample_calibration = 5.9631 * Fluorometer_notional_calibration - 0.1897 9 0.997 22 Fluorometer_sample_calibration = 5.8310 * Fluorometer_notional_calibration - 0.1668 9 0.984 23 Fluorometer_sample_calibration = 6.1882 * Fluorometer_notional_calibration - 0.2173 9 0.987 24 Fluorometer_sample_calibration = 4.9801 * Fluorometer_notional_calibration - 0.0942 9 0.997 25 Fluorometer_sample_calibration = 5.6851 * Fluorometer_notional_calibration - 0.1547 9 0.997 26 Fluorometer_sample_calibration = 5.9277 * Fluorometer_notional_calibration - 0.1109 9 0.997 27 Fluorometer_sample_calibration = 5.4055 * Fluorometer_notional_calibration - 0.1422 9 0.991 28 Fluorometer_sample_calibration = 4.8403 * Fluorometer_notional_calibration - 0.1017 9 0.981 29 Fluorometer_sample_calibration = 4.8286 * Fluorometer_notional_calibration - 0.1010 9 0.992 30 Fluorometer_sample_calibration = 3.8775 * Fluorometer_notional_calibration - 0.0101 9 0.973 31 Fluorometer_sample_calibration = 4.4803 * Fluorometer_notional_calibration - 0.1694 9 0.992 32 Fluorometer_sample_calibration = 4.2230 * Fluorometer_notional_calibration - 0.0499 9 0.972 33 Fluorometer_sample_calibration = 4.0833 * Fluorometer_notional_calibration - 0.1495 8 0.993 34 Fluorometer_sample_calibration = 3.5766 * Fluorometer_notional_calibration - 0.0215 9 0.988 35 Fluorometer_sample_calibration = 3.5113 * Fluorometer_notional_calibration - 0.0453 9 0.994 36 Fluorometer_sample_calibration = 3.5150 * Fluorometer_notional_calibration - 0.0029 9 0.993 37 Fluorometer_sample_calibration = 4.4823 * Fluorometer_notional_calibration - 0.0955 9 0.991 38 Fluorometer_sample_calibration = 4.3764 * Fluorometer_notional_calibration - 0.0530 9 0.986 39 Fluorometer_sample_calibration = 3.9448 * Fluorometer_notional_calibration - 0.0912 8 0.982 40 Fluorometer_sample_calibration = 3.0322 * Fluorometer_notional_calibration - 0.0695 9 0.986 41 Fluorometer_sample_calibration = 4.1221 * Fluorometer_notional_calibration - 0.1559 9 0.986 42 Fluorometer_sample_calibration = 4.1598 * Fluorometer_notional_calibration - 0.1610 9 0.989 43 Fluorometer_sample_calibration = 3.4495 * Fluorometer_notional_calibration - 0.0421 9 0.985 44 Fluorometer_sample_calibration = 3.3423 * Fluorometer_notional_calibration - 0.1047 9 0.991 45 Fluorometer_sample_calibration = 3.3245 * Fluorometer_notional_calibration - 0.0606 9 0.991 46 Fluorometer_sample_calibration = 3.2269 * Fluorometer_notional_calibration - 0.0588 8 0.967 47 Fluorometer_sample_calibration = 3.2259 * Fluorometer_notional_calibration - 0.0562 9 0.981 48 Fluorometer_sample_calibration = 2.9604 * Fluorometer_notional_calibration - 0.0314 9 0.991 49 Fluorometer_sample_calibration = 3.6024 * Fluorometer_notional_calibration - 0.0055 9 0.994 50 Fluorometer_sample_calibration = 4.0113 * Fluorometer_notional_calibration - 0.1220 9 0.996 51 Fluorometer_sample_calibration = 4.2284 * Fluorometer_notional_calibration - 0.1235 9 0.994 52 Fluorometer_sample_calibration = 5.2939 * Fluorometer_notional_calibration - 0.1864 9 0.989 53 Fluorometer_sample_calibration = 5.0839 * Fluorometer_notional_calibration - 0.1953 9 0.989 54 Fluorometer_sample_calibration = 5.5773 * Fluorometer_notional_calibration - 0.2282 9 0.997 55 Fluorometer_sample_calibration = 5.1467 * Fluorometer_notional_calibration - 0.1869 9 0.998 56 Fluorometer_sample_calibration = 4.0049 * Fluorometer_notional_calibration - 0.1162 9 0.993 57 Fluorometer_sample_calibration = 4.4884 * Fluorometer_notional_calibration - 0.1096 9 0.981 58 Fluorometer_sample_calibration = 3.4519 * Fluorometer_notional_calibration - 0.0553 9 0.976 59 Fluorometer_sample_calibration = 4.0568 * Fluorometer_notional_calibration - 0.0877 9 0.996 60 Fluorometer_sample_calibration = 2.9045 * Fluorometer_notional_calibration - 0.0523 9 0.987 61 Fluorometer_sample_calibration = 5.2855 * Fluorometer_notional_calibration - 0.2035 9 0.995 62 Fluorometer_sample_calibration = 2.5394 * Fluorometer_notional_calibration - 0.1204 9 0.985 63 Fluorometer_sample_calibration = 3.3750 * Fluorometer_notional_calibration - 0.1334 9 0.979 64 Fluorometer_sample_calibration = 2.5498 * Fluorometer_notional_calibration - 0.1574 9 0.985 65 Fluorometer_sample_calibration = 4.2106 * Fluorometer_notional_calibration - 0.1769 9 0.950 66 Fluorometer_sample_calibration = 2.0404 * Fluorometer_notional_calibration - 0.0815 9 0.988 67 Fluorometer_sample_calibration = 3.0322 * Fluorometer_notional_calibration - 0.1022 9 0.862 68 Fluorometer_sample_calibration = 1.9791 * Fluorometer_notional_calibration - 0.0596 9 0.996 69 Fluorometer_sample_calibration = 2.7926 * Fluorometer_notional_calibration - 0.0939 9 0.908 70 Fluorometer_sample_calibration = 1.1972 * Fluorometer_notional_calibration - 0.0465 6 0.887 71 Fluorometer_sample_calibration = 1.7245 * Fluorometer_notional_calibration - 0.0199 9 0.886 72 Fluorometer_sample_calibration = 1.4014 * Fluorometer_notional_calibration - 0.0589 9 0.512 73 Fluorometer_sample_calibration = 1.7341 * Fluorometer_notional_calibration - 0.0162 9 0.965 74 Fluorometer_sample_calibration = 2.4120 * Fluorometer_notional_calibration - 0.0734 9 0.997 The reduction in the RMS residual (uncalibrated = 0.347, calibrated = 0.137) over the entire cruise indicated an improved match to the extracted chl-a sample dataset after calibration.
BODC post-processing and screening
-
Reformatting
The data were converted from tab delimited ODV format into BODC internal format using BODC transfer function 480. Only the final calibrated channels were transferred and the following table shows how these variables were mapped to appropriate BODC parameter codes. Oxygen saturation and sigma-theta were derived and added to the profiles during the transfer.
Originator's Parameter Name Units Description BODC Parameter Code Units Comments Pressure dbar Pressure of the water column PRESPR01 dbar - Temperature_1 °C Temperature of water column by CTD TEMPST01 °C Frame mounted sensor Temperature_2 °C Temperature of water column by CTD TEMPST02 °C Vane mounted sensor Salinity_1_calibrated - Practical salinity of the water body by CTD PSALCC01 - Frame mounted sensor. Calibration against bench salinometer samples Salinity_2_calibrated - Practical salinity of the water body by CTD PSALCC02 - Vane mounted sensor. Calibration against bench salinometer samples Oxygen concentration calibrated ml l-1 Oxygen DOXYSC01 µmol l-1 Calibration against Winkler samples. Unit conversion *44.66 applied. Fluorometer_sample_calibration mg m-3 Chlorophyll-a CPHLPS01 mg m-3 Calibration against extracted chl-a samples PAR_down W m-2 Downwelling PAR irradiance DWIRPP01 W m-2 - PAR_up W m-2 Upwelling PAR irradiance UWIRPP01 W m-2 - Beam transmissance % Beam transmissance in the water column POPTDR01 % - Beam attenuance m-1 Beam attenuance in the water column ATTNDR01 m-1 - - - Oxygen saturation OXYSSC01 % Generated by BODC using the Benson and Krause (1984) algorithm with parameters DOXYSC01, PSALCC01 and TEMPST01 - - Sigma-theta SIGTPR01 kg m-3 Generated by BODC using the Fofonoff and Millard (1982) algorithm from frame mounted sensors. - - Potential temperature POTMCV01 °C Generated by BODC using the Fofonoff and Millard (1982) algorithm from frame mounted sensors. -
References
Benson, B.B. and Krause, D., 1984. The concentration and isotopic fractionation of oxygen dissolved in freshwater and seawater in equilibrium with the atmosphere. Limnology and Oceanography, 29(3), 620-632.
Fofonoff, N.P. and Millard, R.C., 1983. Algorithms for computations of fundamental properties of seawater. UNESCO Technical Papers in Marine Science No. 44, 53pp.
-
Screening
Reformatted CTD data were transferred onto a graphics work station for visualisation using the in-house editor EDSERPLO. No data values were edited or deleted. Flagging was achieved by modification of the associated BODC quality control flag for suspect or null values.
The vane mounted sensors suffered more from spiking and spuious data values than did the sensors in the frame and therefore the primary temperature, salinity and density were retained for banking in the NODB, while the secondary channels were discarded.
Banking
The profiles were banked to the National Oceanographic Database (NODB) following BODC procedures.
Project Information
No Project Information held for the Series
Data Activity or Cruise Information
Cruise
Cruise Name | JC079 (AMT22) |
Departure Date | 2012-10-10 |
Arrival Date | 2012-11-24 |
Principal Scientist(s) | Glen A Tarran (Plymouth Marine Laboratory) |
Ship | RRS James Cook |
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 |
B | nominal value |
Q | value below limit of quantification |