Metadata Report for BODC Series Reference Number 1084654

• 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

Data Access Policy

Open Data supplied by Natural Environment Research Council (NERC)

You must always use the following attribution statement to acknowledge the source of the information: "Contains data supplied by Natural Environment Research Council."

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.

Instrument Descriptions UCCTD JC057

Titanium CTD Unit and Auxiliary Sensors

Depth profiles for dissolved and suspended particulate TEIs were obtained using the NIOZ Ultra Clean sampling system.

The system consists of 3 major modules:

A box-shaped titanium CTD frame with 24 Ultraclean PRISTINE 27 litre water samplers with butterfly lids and Teflon valves. The UC samplers are produced by NIOZ and are made of PVDF and titanium. Due to the butterfly-type closure on both ends of the sampler the flow-through is excellent. The samplers are controlled with a hydraulic system.

A clean air container for contamination-free (sub)sampling

A deep sea winch with a an iron free Kevlar CTD-cable

To avoid contamination the frame of the UCC- system is made of titanium and all the electronic pressure housing and other parts are made of titanium or clean plastics like Teflon, PETP or POM. The frame can be parked and secured 'seasave' inside the clean air container. Prior to a cast the frame is prepared inside this container and transported to the CTD-launching spot. After the cast the frame can be returned to the clear air container within minutes thereby avoiding contamination of the equipment from the ship.

The electronic system consists of a SBE 9 plus CTD, a SBE 11 plus V2 Deck Unit and a NIOZ developed multivalve bottle-controller with the use of the following additional sensors:

For in situ calibration of the profiling thermometer a high-accuracy reference-thermometer (SBE 35) was installed, for bottom detection 2 devices were installed: A Benthos PSA-916 altimeter and a bottom switch with a weight.

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.

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.

BODC Processing JC057

Reformatting

The data arrived at BODC as 44 ASCII files (22 standard CTD casts and 22 trace metal CTD casts) representing all of the CTD casts taken during the cruise. Data were reformatted to BODC internal QXF format (subset of NETcdf). The following table shows how the variables within the ASCII files were mapped to the appropriate BODC parameter codes.

BODC assigned each CTD event with a unique identifier (OID) based on the originator's event log. OID was assembled from the originator's station, cast number and cast type i.e. 01_01_UCC (station_cast_cast type). Definition of CAST TYPE
ROS -CTD with 25 dm3 bottle in rosette sampler
UCC -CTD with 27 dm3 bottles in Ultra Clean frame
ISP- sampling with In Situ Pump

Screening

Reformatted CTD data were visualised using the in-house graphical editor EDSERPLO. No data values were edited or deleted. Quality control flags were applied to data as necessary.

References

Fofonoff, NP and Millard, RC (1983). Algorithms for computations of fundamental properties of seawater. UNESCO Technical Papers in Marine Science No. 44, 53pp.

UNESCO, 1981. Background papers and supporting data on the International Equation of State of Seawater 1980. UNESCO Technical Papers in Marine Science No. 38, 192pp

Originator's Data Processing JC057

Sampling Strategy

The main objective of the RRS James Cook (JC057) cruise was to complete the third and last leg of the Dutch Geotraces project. The Dutch Geotraces project aimed to map the distribution of important trace elements and isotopes in the West Atlantic Ocean. With 18 full depth stations sampled during this cruise (leg 3) a transect of 59 stations from 65°N to 50°S was completed. On board were scientists from Brazil, Germany, France, UK, USA, Austria and the Netherlands. An extensive set of parameters were sampled with direct on board measurement of Fe, Al, Mn, Co, Zn, Cd, the CO2 system, nutrients, organic speciation, size fractionation of Fe, 234Th, bacterial and Archaeal production. Additional samples were also collected for the international community for the following parameters Ag, Pt, Cu, Zn, Hg, Ba, U, Mo, REE, the isotopes of Cd, Cr, Ni, Nd (water column and bottom sediments), Pb, Fe, Zn, Si, 15N, 13/14C, 230Th, 231Pa, 232Th, D and 18O.

Two CTD systems, both with large volume samplers were used throughout the cruise (ultraclean all-titanium trace metal clean CTD and a 25L stainless steel CTD rosette). Overall 12 normal stations (st 1, 3, 4, 5, 7, 8, 10, 11, 13, 15, 16, 18), 2 superstations (st 9, 14) and 4 hyperstations (st 2, 6, 12, 17) were carried out during the cruise. Normal stations typically consisted of 1 CTD 25L and 1 UC CTD to the bottom. Superstations were defined by the additional use of in situ pumps. Hyperstations consisted typically of 1 x CTD 25 L to the bottom, 2 x UC CTD to the bottom and the use of the in situ pumps.

More information can be found in the cruise report.

The Clean CTD frame was parked and 'seasave' secured inside the clean air container. Prior to a cast the frame was prepared inside that container and transported to the CTD-launching spot using a custom made aluminium pallet and an extra long forklift. After each clean CTD cast the frame was returned to the clear air container within minutes avoiding contamination of the equipment with grease, rust or smoke particles from the ship. After closing of the container the air treatment system was started to clean the air using HEPA-filters and the frame, bottles and electronics were rinsed with fresh water.

Data Processing

All CTD data was processed using Seasave V7.20 and SBE Data Processing V7.20.

The CTD data were recorded with a frequency of 24 data cycles per second. A bottle file was produced from the up cast for each CTD. The raw CTD data were processed and reduced to ASCII files, giving 1 dbar values. Full data processing was completed at NIOZ, Texel using WOCE guidelines.

Field Calibrations

Discrete salinity and oxygen samples were collected to calibrate the CTD sensor data, all calibrations were performed by NIOZ.

Project Information

GEOTRACES

Introduction

GEOTRACES is an international programme sponsored by SCOR which aims to improve our understanding of biogeochemical cycles and large-scale distribution of trace elements and their isotopes (TEIs) in the marine environment. The global field programme started in 2009 and will run for at least a decade. Before the official launch of GEOTRACES, fieldwork was carried out as part of the International Polar Year (IPY)(2007-2009) where 14 cruises were connected to GEOTRACES.

GEOTRACES is expected to become the largest programme to focus on the chemistry of the oceans and will improve our understanding of past, present and future distributions of TEIs and their relationships to important global processes.

This initiative was prompted by the increasing recognition that TEIs are playing a crucial role as regulators and recorders of important biogeochemical and physical processes that control the structure and productivity of marine ecosystems, the dispersion of contaminants in the marine environment, the level of greenhouse gases in the atmosphere, and global climate.

Scientific Objectives

GEOTRACES mission is: To identify processes and quantify fluxes that control the distribution of key trace elements and isotopes in the ocean, and to establish the sensitivity of these distributions to changing environmental conditions.

Three overriding goals support the GEOTRACES mission

• Determine ocean distributions of selected TEIs at all major ocean basins
• Evaluate the sources, sinks, and internal cycling of these TEIs and thereby characterize more completely their global biogeochemical cycles
• Provide a baseline distribution in the Polar Regions as reference for assessing past and future changes.

These goals will be pursued through complementary research strategies, including observations, experiments and modelling.

Fieldwork

The central component of GEOTRACES fieldwork will be a series of cruises spanning all Ocean basins see map below.

Three types of cruise are required to meet the goals set out by GEOTRACES. These are

• Section cruises - These will measure all the key parameters (see below) over the full depth of the water column. The sections were discussed and approved by the International GEOTRACES Scientific Steering Committee at the basin workshops.
• Process Studies - These will investigate a particular process relevant to the cycling of trace metal and isotopes. They must follow the "Criteria for Establishing GEOTRACES Process Studies" and be approved by the International GEOTRACES Scientific Steering Committee.
• Cruises collecting GEOTRACES compliant data - These will collect some trace element or isotope data. They must follow the GEOTRACES Intercalibration and Data Management protocols

IPY-GEOTRACES

The IPY-GEOTRACES programme comprised of 14 research cruises on ships from 7 nations; Australia, Canada, France, Germany, New Zealand, Japan and Russia. The cruises will not be classified in the same way as the full GEOTRACES programme since the intercalibration protocols and data management protocols had not been established before the start of the IPY. But IPY-GEOTRACES data will still be quality controlled by GDAC and in the majority of cases verified versus Intercalibration standards or protocols.

Key parameters

The key parameters as set out by the GEOTRACES science plan are as follows: Fe, Al, Zn, Mn, Cd, Cu; 15N, 13C; 230Th, 231Pa; Pb isotopes, Nd isotopes; stored sample, particles, aerosols.

Weblink:

http://www.bodc.ac.uk/geotraces/
http://www.geotraces.org/

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: