Metadata Report for BODC Series Reference Number 1763971
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
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Problem Reports
No Problem Report Found in the Database
UK Ocean Acidification (UKOA) RRS James Clark Ross Cruise JR20120601/JR271 Underway Navigation and Bathymetry Data Quality Report
The navigation data have been through BODC quality control screening. Overall the data for the cruise duration appeared good.
The bathymetric data were also quality controlled during BODC screening procedures. There were extensive periods of large-scale noise that hide the real bathymetry in the channel. On these occasions, flags have been applied to the whole section. For time periods where the noise was clearly above or below the bathymetric signal, the data points were flagged as suspect. Users should use caution when interpreting the bathymetric depth channel due to the highly noisy nature of the channel.
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
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
| Maximum Ping rate | 20 Hz |
| Resolution | 1 cm |
| Accuracy | 1 cm at 710 and 200 kHz |
| Operating frequencies | 1 or 2 kHz |
| Single Beam frequencies | 12, 18, 33, 38, 50, 70, |
| Dynamic range | 160 dB |
Further details can be found in the manufacturer's specification sheet.
Kongsberg Seatex Seapath 320+ Precise Heading, Attitude and Positioning Sensor
The Seapath 320+ is a navigational system that combines two Global Navigation Satellite System (GNSS) receivers with a MRU 5+ inertial sensor to provide high resolution and accuracy positional data. The inertial sensor employs linear accelerometers and unique microelectromechanical systems (MEMS)-type angular rate gyros to provide 0.01 RMS pitch and roll accuracy. The GNSS receivers can use multiple satellite constellations (GPS, GLONASS and Galileo, when available), and combine data from these to improve heading and positional measurements. In case of missing data from one GNSS receiver, the other receiver provides position and velocity, and the inertial sensor provides heading from its internal rate sensors.
The main characteristics are presented below, and the specification sheet can be accessed here Kongsberg Seatex Seapath 320+ .
Specifications
| Heading accuracy | 0.04° RMS (4m baseline) 0.065° RMS (2.5 baseline) |
| Roll and pitch accuracy | 0.02° RMS for ± 5° amplitude |
| Scale factor error in roll, pitch and heading | 0.05% RMS |
| Heave accuracy (real time) | 5 cm or 5%, whichever is highest |
| Heave accuracy (delayed signal) | 2 cm or 2%, whichever is highest |
| Heave motion periods (real time) | 1 to 20 seconds |
| Heave motion periods (delayed signal) | 1 to 50 seconds |
| Position accuracy (DGPS/DGlonass) | 1 m (95% CEP) |
| Position accuracy (SBAS) | 1 m (95% CEP) |
| Position accuracy (with RTK corrections) | 0.2 m (95% CEP) |
| Velocity accuracy | 0.07 m s-1 (95% CEP) |
| Data update rate | Up to 100Hz |
Sperry Marine MK-37 Gyrocompass
A family of instruments that contain a controlled gyroscope which seeks and aligns itself with the meridian and points to true north. They use the properties of the gyroscope in combination with the rotation of the earth and the effect of gravity. The effects of varying speed and latitude are compensated for by the use of manually operated controls. Models MOD I, MOD O, MOD D, MOD D/E are all with an analog output Step or/and Syncro. MOD VT is the latest model with NMEA Data output as well.
Further specifications for MOD VT can be found in the manufacturer's specification document.
Further information for MOD D/E can be found in the user manual.
UK Ocean Acidification (UKOA) RRS James Clark Ross Cruise JR20120601/JR271 Underway Navigation and Bathymetry Instrumentation
The navigation instruments used to collect this dataset are displayed in the table below.
| Manufacturer | Model | Parameter measured |
| Ashtech | ADU-5 GPS | Positional data |
| Ashtech | GLONASS GG24 GPS | Ship's speed and direction (over ground) |
| Seatex | Seapath 320+ | Ship's Orientation and navigation |
| Sperry Marine Gyro | Mk37 Model D | Heading |
| Simrad Kongsberg | EA600 | Echo sounder bathymetry |
| Chernikeef Aquaprobe | Mk5 Aquaprobe | Ship's speed |
UK Ocean Acidification (UKOA) RRS James Clark Ross Cruise JR20120601/JR271 Underway Navigation and Bathymetry Data Processing Document
Originator's Data Processing
The navigation and bathymetric data were measured by several different instruments and the data were logged every second to the SCS system and stored in comma separated format ACO files. The header information was stored in TPL files. Each instrument logged data to one individual file, although many of the original files contained data that were not transferred as they were not relevant to the final dataset.
The transferred latitude and longitude navigation data originated from the Seatex Seapath 320+ GPS as this was the best quality positional dataset out of the original files. Bathymetry data originated from the EA600 Kongsberg echo sounder and the ship's orientation originated from the Sperry Marine gyrocompass and Ashtech GPS. The ship's speed and direction over ground came from the Furuno GPS. The speed through water and total distance originated from the Chernikeef Aquaprobe.
The table below shows details of the original files that were delivered to BODC.
| Filename | Content Description | Start Date | Start Time | End Date | End Time |
| seatex-gga.ACO | Position | 01/06/2012 | 14:40:31 | 05/07/2012 | 13:00:51 |
| emlog-vlw.ACO | Distance | 01/06/2012 | 14:40:31 | 05/07/2012 | 13:00:50 |
| gyro.ACO | Heading | 01/06/2012 | 14:40:30 | 05/07/2012 | 13:00:50 |
| furuno-vtg.ACO | Ship's speed and direction over ground | 01/06/2012 | 14:40:31 | 05/07/2012 | 13:00:50 |
| emlog-vhw.ACO | Ship's speed through water | 01/06/2012 | 14:40:32 | 05/07/2012 | 13:00:49 |
| ea600.ACO | Bathymetry | 01/06/2012 | 17:40:32 | 05/07/2012 | 13:00:25 |
BODC Data Processing
Reformatting
The underway data were reformatted from the originator's ASCII format to BODC's in-house standard. All parameters were merged into a single file, with a common time channel. Data supplied at higher frequency than the BODC file were bin-averaged to the appropriate time-interval. The channel has an interval of 60 seconds.
The originator's variables were mapped to the appropriate BODC parameter codes as follows:
| Originator's file | Originator's parameter | Originator's Units | Description | BODC parameter | BODC Units | Conversion Factor | Comments |
|---|---|---|---|---|---|---|---|
| seatex-gga.ACO | lat | Degrees (+ve N) | Latitude north (WGS84) by Seatex Seapath DGPS | ALATGP01 | Degrees (+ve N) | ||
| seatex-gga.ACO | lon | Degrees (+ve E) | Longitude east (WGS84) by Seatex Seapath DGPS | ALONGP01 | Degrees (+ve E) | ||
| Distance traveled | DSRNCV01 | m | Channel derived using Matlab routine from Seatex navigation channels | ||||
| gyro.ACP | heading | degrees | Orientation (horizontal relative to true north) of measurement platform {heading} by compass | HEADCM01 | degrees | ||
| Eastward velocity (over ground) of measurement platform | APEWGP01 | cm s-1 | Channel derived after transfer using BODC Matlab routine 'velcal' | ||||
| Northward velocity (over ground) of measurement platform | APNSGP01 | cm s-1 | Channel derived after transfer using BODC Matlab routine 'velcal' | ||||
| depth | ea600.ACO | m | Sea-floor depth (below instantaneous sea level) {bathymetric depth} in the water body by echo sounder | MBANZZ01 | m | ||
| furuno-vtg.ACO | sog | knots | Speed (over ground) of measurement platform by unspecified GPS system | APSAGP01 | m s-1 | * 0.514444 | Channel not transferred |
| furuno-vtg.ACO | cmg | degrees | Direction of motion (over ground) of measurement platform {course made good} by unspecified GPS system | APDAGP01 | degrees | Channel not transferred | |
| ashtech.ACO | pitch | degrees | Orientation (pitch) of measurement platform by unspecified GPS system | PTCHGP01 | degrees | Channel not transferred | |
| ashtech.ACO | roll | degrees | Orientation (roll angle) of measurement platform by unspecified GPS system | ROLLGP01 | degrees | Channel not transferred | |
| emlog-vhw.ACO | velocity_f | knots | Speed (through water) of measurement platform by electromagnetic log | APSAWW01 | m s-1 | * 0.514444 | Channel not transferred |
Data Processing
Navigation channels
Latitude and longitude channels were checked and the best quality channels were from the seatex.ACO file. BODC Matlab procedure 'navint' was run to interpolate the 1 minute gap present between 2012/06/05 09:16:00 and 2012/06/05 09:17:00.
Distance Run
Distance run was re-derived using the seatex latitude and longitude channels using the BODC Matlab utility 'disrun'.
Ship's north and east velocity
The ship's north and east velocities were re-derived using BODC Matlab routine 'velcal'.
Screening
Each data channel was inspected on a graphics workstation and any spikes or periods of dubious data were flagged. The power of the workstation software was used to carry out comparative screening checks between channels by overlaying data channels. A map of the cruise track was simultaneously displayed in order to take account of the oceanographic context.
Calibrations
No sample or manufacturer's calibrations were applied to the navigation or bathymetry data.
Project Information
UKOARP Theme B: Ocean acidification impacts on sea surface biology, biogeochemistry and climate
The overall aim of this theme is to obtain a quantitative understanding of the impact of ocean acidification (OA) on the surface ocean biology and ecosystem and on the role of the surface ocean within the overall Earth System.
The aims of the theme are:
- To ascertain the impact of OA on planktonic organisms (in terms of physiological impacts, morphology, population abundances and community composition).
- To quantify the impacts of OA on biogeochemical processes affecting the ocean carbon cycle (both directly and indirectly, such as via availability of bio-limiting nutrients).
- To quantify the impacts of OA on the air-sea flux of climate active gases (DMS and N2O in particular).
The main consortium activities will consist of in-situ measurements on three dedicated cruises, as well as on-deck bioassay experiments probing the response of the in-situ community to elevated CO2. Most of the planned work will be carried out on the three cruises to locations with strong gradients in seawater carbon chemistry and pH; the Arctic Ocean, around the British Isles and the Southern Ocean.
Weblink: http://www.oceanacidification.org.uk/research_programme/surface_ocean.aspx
Data Activity or Cruise Information
Cruise
| Cruise Name | JR20120601 (JR271) |
| Departure Date | 2012-06-01 |
| Arrival Date | 2012-07-02 |
| Principal Scientist(s) | Ray Leakey (Scottish Association for Marine Science) |
| Ship | RRS James Clark Ross |
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 |
