Metadata Report for BODC Series Reference Number 1113642

• 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

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

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.

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:

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:

* 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

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:

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

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:

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

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: