Metadata Report for BODC Series Reference Number 1903748
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 JR16003 Navigation quality control report
Bathymetry
The single beam bathymetry channel displays a large amount of noise away from the baseline bathymetry. Extensive periods of noise have been flagged as well as isolated spikes to clean up the noise in the data. Drop outs of zero values were converted to the absent data value.
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 JR16003 navigation instrumentation
The following scientific navigational and bathymetric systems were fitted.
| Manufacturer | Model | Function | Comments |
| Seatex | Seapath 320+ | GPS (latitude, longitude) | Primary source of position for science. |
| Kongsberg Maritime | Simrad EA600 | Single-beam echo sounder (hull) | Best quality bathymetry source |
| Kongsberg Maritime | Simrad EM120 | Multi-beam echo sounder (deep) | |
| Sperry Marine | MK37 series gyrocompasses | GPS (ships heading) |
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 JR16003 Navigation and Bathymetry Processing Procedures 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. Each instrument logged data to one individual file and the associated header information is stored in TPL files.
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 Discription | Format | Interval | Start date | Start Time | End date | End Time |
| seatex-gga.ACO | Latitude and Longitude | ASCII (.ACO) | 1 sec | 04/12/2016 | 12:10:14 | 20/01/2017 | 02:02:16 |
| gyro.ACO | Ships Heading | ASCII (.ACO) | ~1 sec | 04/12/2016 | 12:10:15 | 20/01/2017 | 02:02:03 |
| ea600.ACO | Single-beam echo-sounder | ASCII (.ACO) | ~1 sec | 06/12/2016 | 22:32:32 | 20/01/2017 | 02:01:07 |
| em122.ACO | Multi-beam echo-sounder | ASCII (.ACO) | ~1 sec | 06/12/2016 | 22:32:32 | 20/01/2017 | 02:01:07 |
BODC Data Processing
The ACO files provided by the originator were transferred into internal BODC format using established BODC data banking procedures. The data were averaged to 60 second intervals. The originators files contained many parameters that were not transferred because they were not relevant to the final data set and several channels were derived by BODC.
The table below provides a description of the originators channels transferred, along with the BODC parameter codes and units assigned. 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 |
| em122.ACO | depth | meters | multi-beam depth by echo-sounder | MBANSWCB | meters | Bathymetry channel dropped, available on request |
Navigation channels
Latitude and longitude channels were checked and the best quality channels were from the seatex.ACO file. A check was run and two gaps in the navigation channels were identified. These were at the start and end of the file and were trimmed off the data streams.
- Gap 1 Start: 2016/12/03 00:00:00 End: 2016/12/04 12:09:00 Duration: 2170 minutes
- Gap 2 Start: 2017/01/20 02:03:00 End: 2017/01/21 00:00:00 Duration: 1318 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
Bathymetry data were screened independently as well as against GEBCO bathymetry measurements. Bathymetry data from the EA600 single-beam echo-sounder were deemed to be the best quality. The multi-beam echo-sounder was switched on later and turned off earlier than the single-beam and so is a shorter time series of data.
Calibration
No sample calibrations were applied to these data.
Project Information
BAS Long Term Monitoring and Survey
Introduction
The Long Term Monitoring and Survey project (LTMS) has been running since the British Antarctic Survey (BAS) was created. This project is one of the BAS core projects, with several groups of scientists collecting various types of data e.g biological, geological, atmospheric, among others.
Data collection is achievable through a wide scope of instruments and platforms, e.g. the Antarctic research stations, autonomous instrument platforms deployed on or from BAS research ships, BAS aircrafts, satellite remote sensing and others.
Scientific Objectives
This project was implemented in order to measure change and variability in the Earth system. Its long term duration allows for the monitoring of processes that could be missed in shorter term studies and experiments. The data collected is also used to check and improve the reliability of models used to stimulate and predict the behavior of the Earth system.
The main objectives are:
- Topographic survey
- Geosciences survey
- Biological survey and monitoring
- Atmospheric and oceanographic monitoring
Data Availability
The data sets obtained through this project are available to the academic community.
Data Activity or Cruise Information
Cruise
| Cruise Name | JR16003 |
| Departure Date | 2016-12-08 |
| Arrival Date | 2017-01-19 |
| Principal Scientist(s) | Sophie Fielding (British Antarctic Survey), Teal R Riley (British Antarctic Survey) |
| 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 |
