Metadata Report for BODC Series Reference Number 1762365
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
Data Description |
|||||||||||||||||||||||||||||||||||||||||
|
|||||||||||||||||||||||||||||||||||||||||
Data Identifiers |
|||||||||||||||||||||||||||||||||||||||||
|
|||||||||||||||||||||||||||||||||||||||||
Time Co-ordinates(UT) |
|||||||||||||||||||||||||||||||||||||||||
|
|||||||||||||||||||||||||||||||||||||||||
Spatial Co-ordinates | |||||||||||||||||||||||||||||||||||||||||
|
|||||||||||||||||||||||||||||||||||||||||
Parameters |
|||||||||||||||||||||||||||||||||||||||||
|
|||||||||||||||||||||||||||||||||||||||||
|
|||||||||||||||||||||||||||||||||||||||||
Problem Reports
No Problem Report Found in the Database
RRS James Clark Ross Cruise JR15001 (AMT25, JR864) Navigation and Bathymetry Data Quality Document
Navigation
The navigation data have been through BODC quality control screening. Overall the data for the cruise duration appear good.
Bathymetry
The bathymetric data were also quality controlled during BODC screening procedures. There were periods of large-scale noise that obscured the baseline bathymetry in the channel. Where this occurred, the sections have been flagged. For time periods where the noise was clearly above or below the bathymetric signal, the data points were also flagged. 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 |
RRS James Clark Ross Cruise JR15001 (AMT25, JR864) Navigation and Bathymetry Instrument Description Document
The navigation instruments used to collect this dataset are displayed in the table below.
| Instrument Manufacturer | Model | Main Function |
| Furuno | GP32 | Ship's speed and course (over ground) |
| Seatex | Seapath 320+ | Ship's position |
| Sperry Marine Gyro | Mk37 Model D | Gyrocompass Heading |
| Simrad Kongsberg | EA600 | Bathymetry by single-beam echo-sounder |
| Kongsberg | EM122 | Bathymetry by multi-beam echo-sounder |
| Chernikeeff Aquaprobe | Mk5 Aquaprobe | Ship's speed through the water |
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.
RRS James Clark Ross Cruise JR15001 (AMT25, JR864) Navigation and Bathymetry 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 ACO format. The header information was in TPL files. Each instrument logged data to one individual file. 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 were obtained from both the EA600 Kongsberg single-beam echo-sounder and the EM122 multi-beam echo-sounder. The ship's orientation comes from the Sperry Marine gyrocompass. The ship's speed and direction over ground came from the Furuno GPS and the speed through water originates from the Chernikeeff Aquaprobe.
The originator's data files exhibited the same common format for the first four columns: Year (yyyy), Julian day.day fraction (days), Julian day (days), day fraction (days). The remaining columns contain the actual data values.
The table below shows the original files delivered to BODC that contained the data in the final data series, along with start and end dates and times of each file.
| Filename | Content Description | Format | Interval | Start date | Start Time | End date | End Time |
| seatex-gga.ACO | Latitude and Longitude | ASCII (.ACO) | 1 sec | 14/09/2015 | 16:54:55 | 04/11/2015 | 14:51:01 |
| gyro.ACO | Ships Heading | ASCII (.ACO) | ~1 sec | 14/09/2015 | 16:54:55 | 04/11/2015 | 14:50:37 |
| furuno-vtg.ACO | Speed and direction over ground | ASCII (.ACO) | ~1 sec | 14/09/2015 | 16:54:55 | 04/11/2015 | 14:50:05 |
| emlog-vhw.ACO | Speed through water | ASCII (.ACO) | ~ 3 sec | 14/09/2015 | 16:54:55 | 04/11/2015 | 14:49:11 |
| ea600.ACO | Single-beam echo-sounder | ASCII (.ACO) | ~1 sec | 14/09/2015 | 16:54:54 | 04/11/2015 | 14:49:08 |
| em122.ACO | Multi-beam echo-sounder | ASCII (.ACO) | ~1 sec | 25/09/2015 | 14:45:47 | 02/11/2015 | 15:43:57 |
BODC Data Processing
The ACO files provided by the originator were transferred into internal BODC format using established BODC data banking procedures. The originators files contained many parameters that were not transferred because they were not relevant to the final data set; some were related with the instruments behaviour or acquisition checks. Several channels were re-derived by BODC.
The table below provides a description of the originators channels transferred, along with the BODC parameter codes and units assigned. Unit conversions were applied when data were supplied in knots and nautical miles. BODC processing procedures then included reduction through averaging, checking navigation channels for improbable values, working out speed over ground, and screening the data for anomalous values.
| Originator's File | Originator's Parameter | Originator's Units | Description | BODC parameter | BODC Units | Comments and unit conversions |
|---|---|---|---|---|---|---|
| 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 | meters | Channel derived using Matlab routine from Seatex navigation channels |
| gyro.ACO | heading | degrees | Orientation (horizontal relative to true north) of measurement platform {heading} by compass | HEADCM01 | degrees | - |
| - | - | - | Eastward velocity (over ground) of measurement platform by unspecified GPS system | APEWGP01 | cm s-1 | Channel derived after transfer using BODC Matlab routine 'velcal' |
| - | - | - | Northward velocity (over ground) of measurement platform by unspecified GPS system | APNSGP01 | cm s-1 | Channel derived after transfer using BODC Matlab routine 'velcal' |
| ea600.ACO | depth | m | Sea-floor depth (below instantaneous sea level) {bathymetric depth} in the water body by echo sounder | MBANZZ01 | meters | Best quality bathymetry channel |
| furuno-vtg.ACO | sog | knots | Speed (over ground) of measurement platform by unspecified GPS system | APSAZZ01 | m s-1 | * 0.514444. Channel not transferred to final series. |
| furuno-vtg.ACO | cmg | degrees | Direction of motion (over ground) of measurement platform {course made good} by unspecified GPS system | APDAZZ01 | degrees | Channel not transferred to final series. |
| emlog-vhw.ACO | velocity_f | knots | Speed (through water) of measurement platform by electromagnetic log | APSAWW01 | m s-1 | * 0.514444. Channel not transferred to final series. |
| em122.ACO | depth | meters | multi-beam depth by echo-sounder | MBANSWCB | meters | Channel not transferred to final series. |
| - | - | - | GEBCO depth | MBANGB08 | meters | Channel added by BODC during processing. Channel not transferred to final series. |
Navigation channels
Latitude and longitude channels were checked and the best quality channels were from the seatex.ACO file. There were only gaps at the start and end of the file. These gaps were trimmed off the data stream.
- Gap 1 Start: 2015/09/13 00:00:00 End: 2015/09/14 16:54:30 Duration: 2455 minutes
- Gap 2 Start: 2015/11/04 14:51:30 End: 2015/11/05 00:00:00 Duration: 549 minutes
Distance Run
Distance run was re-derived using the seatex latitude and longitude channels using the BODC Matlab utility 'disrun'.
Ship velocities
The ship's north and east velocities were re-derived using the seatex latitude and longitude channels, using the BODC Matlab routine 'velcal'.
Bathymetry
A channel was added to the dataset for the sea-floor depth (below mean sea level) in the water body by derivation from GEBCO_08 30 arc-second global grid. This was to aid in screening the single and multi-beam echo-sounder channels. There was good agreement between the GEBCO depth and bathymetry channels where the bathymetry line was clear.
Calibrations
No sample or manufacturers calibrations were applied to these data.
Project Information
No Project Information held for the Series
Data Activity or Cruise Information
Cruise
| Cruise Name | JR15001 (AMT25, JR864) |
| Departure Date | 2015-09-15 |
| Arrival Date | 2015-11-04 |
| Principal Scientist(s) | David Barnes (British Antarctic Survey), Jonathan Sharples (University of Liverpool Department of Earth, Ocean and Ecological Sciences), Tim Smyth (Plymouth Marine Laboratory) |
| 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 |
