Metadata Report for BODC Series Reference Number 2158425

• 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

RRS Discovery DY110 (AMT29) CTD Data Quality Report

BODC flag M is applied to all height from seafloor data (AHSFZZ01) which were collected further than 100m from the sea floor. Beyond this point the altimeter was not able to accurately measure distance from the sea floor.

Spikes in attenuance data (ATTNDR01) have been flagged M by BODC.

Where spikes in temperature (TEMPST01) and salinity (PSALCC01)/ conductivity (CNDCST01) have caused a spike in water density (SIGTPR01), these data have been flagged M.

Data Access Policy

Open 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.

If the Information Provider does not provide a specific attribution statement, or if you are using Information from several Information Providers and multiple attributions are not practical in your product or application, you may consider using the following:

"Contains public sector information licensed under the Open Government Licence v1.0."

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.

Benthos Programmable Sonar Altimeter (PSA) 916 and 916T

The PSA 916 is a submersible altimeter that uses the travel time of an acoustic signal to determine the distance of the instrument from a target surface. It provides the user with high resolution altitude or range data while simultaneously outputting data through a digital serial port. A wide beam angle provides for reliable and accurate range measurements under the most severe operational conditions. The instrument is electronically isolated to eliminate any potential signal interference with host instrument sensors. The PSA 916 is an upgrade of the PSA 900.

The standard model (PSA 916) has an operational depth range of 0 - 6000 m, while the titanium PSA 916T has a depth range of 0 - 10000 m. All other specifications for the two versions are the same.

Specifications

Further details can be found in the manufacturer's specification sheets for the PSA 916 and the PSA 916T.

RRS Discovery DY110 CTD Instrumentation

A stainless steel Sea-Bird 911 plus CTD system was used on cruise DY110. This was mounted on a SBE-32 carousel water sampler holding 24 x 20-litre Niskin bottles. The CTD was fitted with the following scientific sensors:

Some calibration dates are unavailable.

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.

Biospherical Instruments QCP-2350-HP [underwater] PAR sensor

A cosine-corrected PAR quantum irradiance profiling sensor. For use in high-pressure underwater applications with 24 bit ADC systems. Measures light available for photosynthesis on a flat surface. Operation is by a single channel compressed analog output voltage that is proportional to the log of incident PAR (400-700 nm) irradiance. A variant of the QCP-2350 model, it uses a pressure-tolerant BH-4-MP connector. The sensor is designed for operation in waters to depths of up to 10,000 m.

For more information, please see this document: https://www.bodc.ac.uk/data/documents/nodb/pdf/Biospherical_QCP2300_QCP2350_Apr2014.pdf

WETLabs Single-angle Backscattering Meter ECO BB

An optical scattering sensor that measures scattering at 117°. This angle was determined as a minimum convergence point for variations in the volume scattering function induced by suspended materials and water. The measured signal is less determined by the type and size of the materials in the water and is more directly correlated to their concentration.

Several versions are available, with minor differences in their specifications:

• ECO BB(RT)provides analog or RS-232 serial output with 4000 count range
• ECO BB(RT)D adds the possibility of being deployed in depths up to 6000 m while keeping the capabilities of ECO BB(RT)
• ECO BB provides the capabilities of ECO BB(RT) with periodic sampling
• ECO BBB is similar to ECO BB but with internal batteries for autonomous operation
• ECO BBS is similar to ECO BB but with an integrated anti-fouling bio-wiper
• ECO BBSB has the capabilities of ECO BBS but with internal batteries for autonomous operation

Specifications

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.

Originators Data Processing of CTD casts from cruise DY110 (AMT29)

Sampling Strategy

In total 55 CTD cast deployments, including 1 shakedown, were used to obtain profiles of the water column and section plots along the cruise transect from a range of sensors comprising of pressure, temperature, conductivity, oxygen, fluorescence, down-welling and upwelling PAR, turbidity, transmittance, and attenuance. Deployments were conventional profiling casts using 24 x 20L OTE Niskin bottles for sampling water. CTD’s were deployed, weather permitting, at pre-dawn between 04:00 and 04:30 am and at solar noon around 12.30 pm ship time each day. Overall, pre-dawn casts consisted of 29 deployments, including 1 to 250 m, 26 to 500 m, 1 to 1000 m, and 1 to 2000 m. Noon casts included 26 deployments, comprising 3 to 1000 m, 22 to 2000 m, and 1 to 5000 m.

Data Processing

For the processing of the data, the Sea-Bird data collection software Seasave-Win32 were used to record the raw data output from the CTD casts. Processing the raw data occurred daily, following the BODC recommended guidelines using SBE Data processing-Win32 v7.26.7. Outlined below are the processing routines used to convert the raw CTD data into CNV files.

• DatCnv was used for the conversion of the raw binary Sea-Bird files to 24 Hz ASCII (CNV) containing data for up and down casts.
• Bottle Summary was applied for the generation of bottle firing files which contain the mean values of all the variables at the time of bottle firing events.
• WildEdit was applied to the CNV files to remove pressure spikes.
• AlignCTD was used to shift, relative to the pressure, the oxygen sensor by two seconds, to compensate for the lag in the sensor response time.
• CellTM was used to remove the effect of thermal inertia on the conductivity cells.
• SeaPlot was used for the identification of the surface soak for each cast which was removed manually until CTD cast 40, from CTD cast 41 onwards LoopEdit was applied.
• Derive was used for recalculating salinity and oxygen concentrations after the corrections for sensor lag and thermal inertia were applied.
• BinAverage was used to convert 24 Hz ASCII files into 1 dbar downcast files for calibration and visualisation purposes.
• Strip was applied for the removal of the initial salinity and oxygen values produced at the DatCnv stage.

The sensor values obtained at the Bottle Summary stage formed the dataset for calibrating the two CTD salinity sensors and oxygen sensor against discrete bench salinometer measurements and oxygen Winkler titration measurements, respectively. The fluorometer sensor was calibrated post-cruise using AC-9 data calibrated against HPLC data.

Preliminary results

temperature

There were no independent measurements of temperature made during the cruise and the two CTD temperature sensors on the rig returned consistent values. There was no further calibration of these sensors.

Salinity

The salinity sensors were calibrated against discrete salinity measurements (autosal) versus corresponding sensor measurements from the four samples on average collected from CTD casts every day. Further details of these measurements can be found in the NMF-SS cruise report section. Preliminary results of the calibrations indicate good agreement between bench salinometer measurements and CTD sensor values, suggesting there was no significant drift in the sensors. For both sensors, calibration regression parameters were calculated with 95% confidence intervals using a Robust-Regression linear model. Data have been calibrated using the following equation:

Salinity_calibrated = intercept + Slope * Salinity_uncalibrated

Where:

For primary salinity: Slope = -0.00073(±0.00020); Y-intercept = 0.0257 (±0.0072)

For secondary salinity: Slope = -0.00164(±0.00025); Y-intercept = 0.0580 (±0.00890)

Oxygen

Corrected_O2 = 1.027(±0.005) * CTD_O2 + 1.029(±0.936)

Preliminary results of the O₂ calibration indicate good agreement between the O₂ concentrations derived by the sensor and Winkler determinations.

Fluorometer

Two fluorometers were used during the cruise. The first one (SN 88-2960-163) was used for the first 20 casts. It was replaced, after faulting consecutive on the upcast, by the second one (SN 88-2615-126). The wrong Calibration file was used to derive fluorescence Chl concentration for CTD casts DY110_001 to DY110_020, thus, data for these stations must be reprocessed using the corresponding file. However, the voltage values obtained by the first fluorometer were extracted from the original files, and the corresponding calibration equation was applied to obtain the fluorescence Chl concentration.

RRS Discovery DY110 (AMT29) CTD BODC Processing

The CTD data were supplied to BODC as one ODV file which was converted to a .txt file and then transferred to the BODC internal format.

During transfer the originator's variables were mapped to unique BODC parameter codes. The following table shows the parameter mapping.

Following transfer, the data were screened using BODC in-house visualisation software. Improbable data values were assigned the appropriate BODC data quality flag. Missing data values, where present, were changed to the missing data value and assigned a BODC data quality flag.

BODC flag M is applied to all data for AHSFZZ01 which were collected further than 100m from the sea floor. Beyond this point the altimeter was not able to accurately measure distance from the sea floor.

Parameters found in the file and that were not transferred are available upon request. Second sensor parameters have been removed from the final file but can also be provided on request.

Project Information

Marine LTSS: CLASS (Climate Linked Atlantic Sector Science)

Introduction

CLASS is a five year (2018 to 2023) programme, funded by the Natural Environment Research Council (NERC) and extended until March 2024.

Scientific Rationale

The ocean plays a vital role in sustaining life on planet Earth, providing us with both living resources and climate regulation. The trajectory of anthropogenically driven climate change will be substantially controlled by the ocean due to its absorption of excess heat and carbon from the atmosphere, with consequent impacts on ocean resources that remain poorly understood. In an era of rapid planetary change, expanding global population and intense resource exploitation, it is vital that there are internationally coordinated ocean observing and prediction systems so policy makers can make sound evidence-based decisions about how to manage our interaction with the ocean. CLASS will underpin the UK contribution to these systems, documenting and understanding change in the marine environment, evaluating the impact of climate change and effectiveness of conservation measures and predicting the future evolution of marine environments. Over the five-year period CLASS will enhance the cost-effectiveness of observing systems by migrating them towards cutting edge autonomous technologies and developing new sensors. Finally, CLASS will create effective engagement activities ensuring academic partners have transparent access to NERC marine science capability through graduate training partnerships and access to shipborne, lab based and autonomous facilities, and modelling capabilities.

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: