Metadata Report for BODC Series Reference Number 2219280

• 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 James Cook Cruise JC071 navigation quality control report

Bathymetry

Bathymetry obtained from the single-beam echo-sounder contained many signal drop-outs ('0') converted to absent data values. The data also contained a large number of poor signal returns which were edited out where it was clear there was a trace of the sea floor. (BODC assessment)

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

RRS James Cook Cruise JC071 underway document

Cruise details

Kongsberg EA600 Single Beam Echosounder

The EA600 is a single beam echosounder with full ocean depth capability designed for bathymetric surveys. It measures water depth by monitoring the travel time of an acoustic signal that is transmitted from the ship, reflected off the seabed and received back at the ship.

The main components of the system are hull-mounted transducers linked to general purpose transceivers (GPTs). Up to four GPTs, each controlling one or more transducers, may be operated simultaneously. The GPT generates a signal, which is transmitted into the water column as an acoustic pulse by the transducer array, and the returning echo is recorded by the GPT. GPTs are in turn linked to a combined display and processor, where adjustments (such as sound-speed corrections) may be applied to the data. Available frequencies span from 12 to 710 kHz, and each GPT may operate at a separate frequency. A variety of transducers is available for water depths up to 11,000 m.

The EA600 stores all data internally but has a USB port which allows the possibility of connecting a CD-ROM/DVD drive to read and write the data. All echo data can be stored as files: bitmap, sample, depth or sidescan data.

In deeper waters, the EA600 supports a multipulse function, allowing for a higher pinger rate. While on passive mode, the pinger is normally attached to a device, with the purpose of tracking and displaying its current depth.

The EA600 replaced the EA500 in 2000.

Specifications

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

Chernikeeff Aquaprobe Mk5 Electromagnetic Speed Log

The Aquaprobe Mk5 EM Speed Log operates on the principle that a conductor (such as water) passing through an electromagnetic field will create a voltage whose magnitude increases as the speed of the conductor increases. The EM log includes one or two hull-mounted transducers, which generate an electromagnetic field and measure the voltage created by the flow of water through that field, thereby deducing the speed of the vessel through the water.

The EM log has the options of single or twin transducers, single or dual axis speed measurements and gate-valved (retractable) hull fitting or fixed transducers. The microprocessor calibration control ensures a high accuracy through the entire speed range.

Specifications

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

RRS James Cook Cruise JC071 navigation instrumentation

Instrumentation

The POSMV was used as the primary positional source in the RVS process, bestnav. The POSMV was used as the primary gyro source in the RVS process, relmov. The single beam echo sounder used a constant sound velocity of 1500 m s^-1.

Sperry Marine NAVIGAT X MK 2 Digital Gyrocompass

A digital gyrocompass for use in marine navigation. The system comprises a gyrosphere supported in fluid, suspended at a single point. The system can drive up to 4 analogue repeaters and has 5 independent serial outputs and 1 dependent 6 steps/° heading outputs. The NAVIGAT X MK2 is a low cost model based on the NAVIGAT X MK 1 and is a member of the Sperry Marine range of heading sensors, which comprises the NAVIGAT 3000 fiberoptic gyrocompass, the NAVIGAT X MK 1 and the NAVIGAT X MK 2 digital gyrocompasses.

Specifications

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

Trimble Applanix Position and Orientation Systems for Marine Vessels (POSMV)

The Position and Orientation Systems for Marine Vessels (POSMV) is a real time kinematic (RTK) and differential global positioning system (DGPS) receiver for marine navigation. It includes an inertial system that provides platform attitude information. The instrument provides accurate location, heading, velocity, attitude, heave, acceleration and angular rate measurements.

There are three models of Applanix POSMV, the POS MV 320, POS MV Elite and the POS MV WaveMaster. POS MV 320 and POS MV WaveMaster are designed for use with multibeam sonar systems, enabling adherence to IHO (International Hydrographic Survey) standards on sonar swath widths of greater than ± 75 degrees under all dynamic conditions. The POS MV Elite offers true heading accuracy without the need for dual GPS installation and has the highest degree of accuracy in motion measurement for marine applications.

Specifications

POS MV 320

POS MV WaveMaster

POS MV Elite

¹ One Sigma, depending on quality of differential corrections
² Whichever is greater, for periods of 20 seconds or less

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

RRS James Cook Cruise JC071 navigation data processing procedure

Originator's Data Processing

All underway sensors/instruments were initially logged via the Ifremer TECHSAS (TECHnical and Scientific sensors Acquisition System) system. The data were then broadcast in UDP/IP frames via the on-board LAN. Data were broadcast in two formats: NMEA broadcasting format and XML broadcasting format. The XML broadcast was used to create TECHSAS NetCDF files while the NMEA broadcast was used to transfer data to the RVS Level-C UNIX system where it was parsed into RVS data streams (RVS format files). For more information please see the JC071 cruise report. Data were further processed in Level-C as described below:

bestnav

The process reads position fixes from up to three GPS sources along with the ship's motion as calculated by relmov. The GPS sources are used to populate navigation position in a hierarchal order. When the primary GPS source fails, the program resorts to the secondary GPS source until the primary source resumes and so on. Bestnav will resort to the next GPS system only after the previous source has failed for a specified (user-defined) amount of time. Dead-reckoning is used to fill gaps in the navigation or if all 3 GPS systems fail. Dead-reckoning of the ship's track is estimated from the relative motion of the ship (as calculated by relmov) and is corrected for ship's drift using an estimated drift velocity. This velocity is estimated from the difference between the dead-reckoned position and GPS fix position at the end of a gap and normalised over time. The POS MV navigational unit was used as the primary GPS source on JC071.

relmov

The process calibrates and calculates the relative movement of the ship. Data are usually obtained from the electromagnetic speed log and ship's gyros, however, alternative gyro sources may be used. The electromagnetic log is calibrated for misalignment, maximum slew rate and a multiplier. The program then calculates the ship's northward and eastward velocities. The relative movement of the ship is used by the bestnav program to calculate the ship's track during dead-reckoning. The POS MV navigational unit was used as the primary gyro source on JC071.

bestdrf

Bestdrf is a product of bestnav. When run, bestnav uses the relmov data which contains a predicted vn and ve (ship's velocities) based upon direction and speed through the water. The bestdrf file is the accurate drift velocity of what actually occurred based on the GPS changes between each record.

Files delivered to BODC

BODC Data Processing

Of the files submitted to BODC, bestnav, adu5pat and ea600m were selected for data banking because they contained the most accurate and processed versions of position, attitude and bathymetry. Data were banked at BODC following standard data banking procedures. The originator's variables were mapped to appropriate BODC parameter codes as follows:

bestnav

adu5pat

ea600m

All the reformatted data were visualised using the in-house EDSERPLO software. Suspect data were marked by adding an appropriate quality control flag, missing data by both setting the data to an appropriate value and setting the quality control flag.

Position

The following gaps and improbable values (identified by improbable ship speeds) were observed in the latitude and longitude channels:

Small gaps (<30 mins) were interpolated. The file was then trimmed to span the length of the data logging (29/04/2012 09:27:00 to 11/05/2012 21:00:00).

Distance Run

Distance run was calculated from the main latitude and longitude channels, starting from the beginning of the file.

Ship Velocities

Although bestnav contained ship velocities, the resultant channels were found to have areas of interpolated data and noisy data. Consequently, the ship velocities were calculated from the main latitude and longitude channels at BODC.

Bathymetry

Zeroes (drop-outs) were removed from bathymetry data. The data were then edited of poor signal returns and corrected for sound velocity (1500 m s^-1) using Carter Areas.

Project Information

Oceans 2025 - The NERC Marine Centres' Strategic Research Programme 2007-2012

Who funds the programme?

The Natural Environment Research Council (NERC) funds the Oceans 2025 programme, which was originally planned in the context of NERC's 2002-2007 strategy and later realigned to NERC's subsequent strategy (Next Generation Science for Planet Earth; NERC 2007).

Who is involved in the programme?

The Oceans 2025 programme was designed by and is to be implemented through seven leading UK marine centres. The marine centres work together in coordination and are also supported by cooperation and input from government bodies, universities and other partners. The seven marine centres are:

• National Oceanography Centre, Southampton (NOCS)
• Plymouth Marine Laboratory (PML)
• Marine Biological Association (MBA)
• Sir Alister Hardy Foundation for Marine Science (SAHFOS)
• Proudman Oceanographic Laboratory (POL)
• Scottish Association for Marine Science (SAMS)
• Sea Mammal Research Unit (SMRU)

Oceans2025 provides funding to three national marine facilities, which provide services to the wider UK marine community, in addition to the Oceans 2025 community. These facilities are:

• British Oceanographic Data Centre (BODC), hosted at POL
• Permanent Service for Mean Sea Level (PSMSL), hosted at POL
• Culture Collection of Algae and Protozoa (CCAP), hosted at SAMS

The NERC-run Strategic Ocean Funding Initiative (SOFI) provides additional support to the programme by funding additional research projects and studentships that closely complement the Oceans 2025 programme, primarily through universities.

What is the programme about?

Oceans 2025 sets out to address some key challenges that face the UK as a result of a changing marine environment. The research funded through the programme sets out to increase understanding of the size, nature and impacts of these changes, with the aim to:

• improve knowledge of how the seas behave, not just now but in the future;
• help assess what that might mean for the Earth system and for society;
• assist in developing sustainable solutions for the management of marine resources for future generations;
• enhance the research capabilities and facilities available for UK marine science.

In order to address these aims there are nine science themes supported by the Oceans 2025 programme:

• Climate, circulation and sea level (Theme 1)
• Marine biogeochemical cycles (Theme 2)
• Shelf and coastal processes (Theme 3)
• Biodiversity and ecosystem functioning (Theme 4)
• Continental margins and deep ocean (Theme 5)
• Sustainable marine resources (Theme 6)
• Technology development (Theme 8)
• Next generation ocean prediction (Theme 9)
• Integration of sustained observations in the marine environment (Theme 10)

In the original programme proposal there was a theme on health and human impacts (Theme 7). The elements of this Theme have subsequently been included in Themes 3 and 9.

When is the programme active?

The programme started in April 2007 with funding for 5 years.

Brief summary of the programme fieldwork/data

Programme fieldwork and data collection are to be achieved through:

• physical, biological and chemical parameters sampling throughout the North and South Atlantic during collaborative research cruises aboard NERC's research vessels RRS Discovery, RRS James Cook and RRS James Clark Ross;
• the Continuous Plankton Recorder being deployed by SAHFOS in the North Atlantic and North Pacific on 'ships of opportunity';
• physical parameters measured and relayed in near real-time by fixed moorings and ARGO floats;
• coastal and shelf sea observatory data (Liverpool Bay Coastal Observatory (LBCO) and Western Channel Observatory (WCO)) using the RV Prince Madog and RV Quest.

The data is to be fed into models for validation and future projections. Greater detail can be found in the Theme documents.

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: