Metadata Report for BODC Series Reference Number 1794620
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 JR20130109/JR274 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 EM122 12kHz Multibeam Echosounder
The EM122 is designed to perform seabed mapping to full ocean depth with a high resolution, coverage and accuracy. Beam focusing is applied both during reception and transmission. The system has up to 288 beams/432 soundings per swath with pointing angles, which are automatically adjusted according to achievable coverage or operator defined limits.
This model uses both Continuous Wave and Frequency Modulated sweep pulses with pulse compression on reception, in order to increase the maximum useful swath width. The transmit fan is split in several individual sectors, with independent active steering, in order to compensate for the vessel movements.
In multiplying mode, two swaths per ping cycle are generated, with up to 864 soundings. The beam spacing is equidistant or equiangular and the transmit fan is duplicated and transmitted with a small difference in along track tilt, which takes into account depth coverage and vessel speed, to give a constant sounding separation along track. In high density mode, more than one sounding per beam can be produced, such that horizontal resolution is increased and is almost constant over the whole swath.
The EM122 transducers are modular linear arrays in a Mills cross configuration with separate units for transmit and receive. If used to deliver sub-bottom profiling capabilities with a very narrow beamwidth, this system is known as SBP120 Sub-Bottom Profiler.
The specification sheet can be accessed here Kongsberg EM122.
Specifications
Operational frequency | 12 Hz |
Depth range | 20 to 11000 m |
Swath width | 6 x depth, to approximately 30 km |
Pulse forms | Continuous Wave and Frequency Modulated chirp |
Swath profiles per ping | 1 or 2 |
Sounding pattern | equidistant on bottom/equiangular |
Depth resolution of soundings | 1 cm |
Sidelobe suppression | -25 dB |
Suppression of sounding artefacts | 9 frequency coded transmit sectors |
Beam focusing | On transmit (per sector) and on reception (dynamic) |
Swath width control | manual or automatic, all soundings intact even with reduced swath width |
Motion compensation | |
Yaw | ± 10° |
Pitch | ± 10° |
Roll | ± 15° |
EM122 versions
System version | 0.5x1 | 1x1 | 1x2 | 2x2 | 2x4 | 4x4 |
Transmit array (°) | 150x0.5 | 150x1 | 150x1 | 150x2 | 150x2 | 150x4 |
Receive array (°) | 1x30 | 1x30 | 2x30 | 2x30 | 4x30 | 4x30 |
No of beams/swath | 288 | 288 | 288 | 288 | 144 | 144 |
Max no of soundings/swath | 432 | 432 | 432 | 432 | 216 | 216 |
Max no of swaths/ping | 2 | 2 | 2 | 1 | 1 | 1 |
Max no of soundings/ping | 864 | 864 | 864 | 432 | 216 | 216 |
Ashtech GG24 receiver
The GG24 is an all-in-view Global Positioning System (GPS) and Global Navigation Satellite System (GLONASS) receiver that blends GPS and GLONASS into a single position solution. This receiver uses all available satellites from both systems to obtain the best position information.
The three-dimensional position and velocity are calculated when tracking any combination of five satellites. Up to five independent measurements are determined every second, with no interpolation or extrapolation from previous solutions.
Specifications
Parameter | Values |
Operating Temperature | -30°C to 55°C |
Sampling frequency | up to 5 Hz |
Receiver channels | 12 L1 GPS + 12 L1 GLONASS |
Real-Time Position Accuracy | 3.2 m (autonomous) 35.0 m (differential) |
Velocity Accuracy | 0.1 knots |
Further details can be found in the manufacturer's specification sheet.
Ashtech Global Positioning System receivers (ADU series)
The ADU series of Global Positioning System (GPS) receivers are designed to give real-time three-dimensional position and attitude measurements. Attitude determination is based on differential carrier phase measurements between four antennas connected to a receiver, providing heading, pitch and roll, along with three-dimensional position and velocity.
The ADU2 model receives information from 48 channels, while the upgraded model (ADU5) uses 56 channels. The ADU5 also features a unique Kalman filter with user selectable dynamic modes to match operating conditions. It also incorporates signals from Satellite Based Augmentation Systems (SBAS) and features an embedded 2-channel 300 kHz beacon receiver for easy differential GPS (DGPS) operations.
Specifications
Parameter | ADU2 | ADU5 |
Operational Temperature range: | | |
Sampling frequency | 5 Hz | 5 Hz |
Receiver channels | 48 | 56 |
Accuracy: | | |
Circular Error Probability: | | |
Further details can be found in the manufacturer's specification sheets for the ADU2 andADU5.
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
Speed Range | ± 40 knots or ± 80 knots |
Total distance range | 0 to 99999.99 nm |
System accuracy | |
Speed < 10 knots | ± 0.02 knots |
Speed > 10 knots | ± 0.2% |
Distance | 0.02% of speed |
Calibrated accuracy | |
Speed < 10 knots | ± 0.1 knots |
Speed > 10 knots | ± 1% |
Distance | 0.02% of speed |
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 JR20130109/JR274 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 main computer system (SCS) and stored in comma separated ACO format. Corresponding TPL files contained the header information for each of the ACO files. Each instrument logged data to one individual file. The SCS data files were submitted to BODC for post-cruise processing and data banking.
BODC Data Processing
Reformatting
The ACO underway data files were merged into a single binary merge file using time as the primary linking key. The time span of the file was from 03/01/2013 22:53:00 to 16/02/2013 14:34:00, with a sampling interval of 60 seconds.
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 heading originated from the Sperry Marine gyrocompass.
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 and parameter | Units | Description | BODC parameter | Units | Comments |
---|---|---|---|---|---|
seatex-gga.ACO, lat | Degrees (+ve N) | Latitude north (WGS84) by Seatex Seapath DGPS | ALATSP01 | Degrees (+ve N) | - |
seatex-gga.ACO, lon | Degrees (+ve E) | Longitude east (WGS84) by Seatex Seapath DGPS | ALONSP01 | 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 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 | 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. |
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.
Data Processing
NavigationA program was run which located any null values in the latitude and longitude channels and checked to ensure that the ship's speed did not exceed 15 knots. No speed check fails or gaps were identified.
The ship's north and east velocities were derived from the seatex latitude and longitude channels using BODC Matlab routine 'velcal'.
Distance run was derived from the seatex latitude and longitude channels using the BODC Matlab utility 'disrun'.
Calibrations
No field or manufacture calibrations were applied to the navigation and bathymetry data at BODC.
UK Ocean Acidification (UKOA) RRS James Clark Ross Cruise JR20130109/JR274 Underway Navigation and Bathymetry Instrumentation
The instruments used to collect the navigation and bathymetry datasets are displayed in the table below.
Instrument | Type | Main role |
Ashtech | ADU-5 GPS | - |
Ashtech | GLONASS GG24 GPS | Ship's speed and direction (over ground) |
Seatex | Seapath 320+ | Ship's Orientation |
Sperry Marine Gyro | Mk37 Model D | Gyrocompass |
Simrad Kongsberg | EM122 | Multi-beam bathymetry |
Chernikeeff Aquaprobe | Mk5 Aquaprobe | Ship's speed |
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 | JR20130109 (JR274) |
Departure Date | 2013-01-09 |
Arrival Date | 2013-02-12 |
Principal Scientist(s) | Geraint Tarling (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 |