Metadata Report for BODC Series Reference Number 2046970
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
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
Kongsberg EA640 Single Beam Echosounder
The EA640 single beam echosounder comprises a standard EA600 (fitted with a standard transducer) and an additional, non-standard 10 kHz transducer.
The standard 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.
Specifications for a standard EA600 echosounder
| 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 for the standard EA600 system.
RRS Discovery cruise DY103 navigation instrumentation
Instrumentation
| Manufacturer | Model | Function | Comments |
| Trimble/Applanix | POSMV | DGPS and attitude | Secondary source of position for science. Used as primary source of GPS at BODC. |
| Kongsberg Maritime | Simrad EA640 | Single-beam echo sounder (hull) | Corrected with constant sound velocity of 1500 ms-1 |
| Kongsberg Maritime | Simrad EM122 | Multi-beam echo sounder (shallow) | Corrected for local sound velocity using sound velocity profiles. The multi-beam was turned off for the majority of the cruise. |
The EA640 single-beam echo-sounder was run throughout the cruise. The 10 kHz was run in free-running mode, while the 12 kHz remained in passive. Pulse parameters were altered during the cruise in response to changing depth. It was used with a constant sound velocity of 1500 ms-1 throughout the water column .
The EM122 multibeam echo-sounder was not run throughout the cruise, likely to prevent interference with other onboard science activities. The position and attitude data were initially supplied from the Seapath 300+ due to its superior real-time heave.
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
| Componenet | DGPS | RTK | GPS Outage |
|---|---|---|---|
| Position | 0.5 - 2 m 1 | 0.02 - 0.10 m 1 | <2.5 m for 30 seconds outages, <6 m for 60 seconds outages |
| Roll and Pitch | 0.020° | 0.010° | 0.020° |
| True Heading | 0.020° with 2 m baseline 0.010° with 4 m baseline | - | Drift <1° per hour (negligible for outages <60 seconds) |
| Heave | 5 cm or 5% 2 | 5 cm or 5% 2 | 5 cm or 5% 2 |
POS MV WaveMaster
| Accuracy | DGPS | RTK | GPS Outage |
|---|---|---|---|
| Position | 0.5 - 2 m 1 | 0.02 - 0.10 m 1 | <3 m for 30 seconds outages, <10 m for 60 seconds outages |
| Roll and Pitch | 0.030° | 0.020° | 0.040° |
| True Heading | 0.030° with 2 m baseline | - | Drift <2° per hour |
| Heave | 5 cm or 5% 2 | 5 cm or 5% 2 | 5 cm or 5% 2 |
POS MV Elite
| Accuracy | DGPS | RTK | GPS Outage |
|---|---|---|---|
| Position | 0.5 - 2 m 1 | 0.02 - 0.10 m 1 | <1.5 m for 60 seconds outages DGPS, <0.5 m for 60 seconds outage RTK |
| Roll and Pitch | 0.005° | 0.005° | 0.005° |
| True Heading | 0.025° | 0.025° | Drift <0.1° per hour (negligible for outages <60 seconds) |
| Heave | 3.5 cm or 3.5% 2 | 3.5 cm or 3.5% 2 | 3.5 cm or 3.5% 2 |
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 Discovery cruise DY103 navigation data processing procedures
Originator's Data Processing
The data were logged by the TECHSAS (TECHnical and Scientific sensors Acquisition System) version 5.11 data logging system which is the main data logging system on NMF-SS operated research vessels. Data were processed daily using the National Oceanography Centre data processing routines into NetCDF files, and these TECHSAS (NetCDF) navigation and bathymetry files provided to BODC were used for BODC processing. Please refer to the cruise report for more information.
Bathymetry
The EA640 was used with a constant sound velocity of 1500 ms-1 throughout the water column to allow it to be corrected for sound velocity in post processing.
The EM122 was fed attitude and position data from the Seapath 300+ system due to its superior real time heave.
Files delivered to BODC
| Filename | Content description | Format | Interval | Start date/time (UTC) | End date/time (UTC) | Comments |
| *-*-position-Applanix_GPS_DY1.gps | Position (lat long) and speed and course over ground | NetCDF | 1 hz | 20-Jun-2019 14:02:51 | 09-Jul-2019 18:04:13 | Best available position |
| *-*-gyro-GYRO1_DY1.gyr | Heading | NetCDF | 1 hz | 20-Jun-2019 14:02:51 | 09-Jul-2019 18:04:12 | - |
| *-*-sb_depth-EM120_DY1.depth | Depths from the EM122 multi-beam echosounder | NetCDF | 10 hz | 07-Jul-2019 16:01:20 | 08-Jul-2019 07:20:48 | - |
| *-*-EA600-EA640_DY1.EA600 | Depths from the EA640 single-beam echosounder | NetCDF | 1 hz | 22-Jun-2019 07:50:16 | 09-Jul-2019 14:51:06 | - |
BODC Data Processing
The data were reformatted to the BODC internal format using standard banking procedures, and averaged at 60 second intervals. The following table shows how variables within the files were mapped to appropriate BODC parameter codes:
*-*-position-Applanix_GPS_DY1.gps
| Originator's variable | Originator's units | Description | BODC Code | BODC Units | Unit conversion | Comments |
| lat | Degrees North | Latitude North | ALATGP01 | Degrees | N/A | - |
| long | Degrees East | Longitude East | ALONGP01 | Degrees | N/A | - |
| gndspeed | Knots | Speed over ground | APSAGP01 | m/s | * 0.5144444 | Knots to m/s |
| gndcourse | Degrees | Course over ground | APDAGP01 | Degrees true | N/A | - |
*-*-gyro-GYRO1_DY1.gyr
| Originator's variable | Originator's units | Description | BODC Code | BODC Units | Unit conversion | Comments |
| Heading | Degrees | True heading | HEADCM01 | Degrees | N/A | - |
*-*-sb_depth-EM120_DY1.depth
| Originator's variable | Originator's units | Description | BODC Code | BODC Units | Unit conversion | Comments |
| swath_depth | Metres | Sea floor depth (swath) | MBANSWCB | Metres | N/A | Dropped as turned off for the majority of the cruise. |
*-*-EA600-EA640_DY1.EA600
| Originator's variable | Originator's units | Description | BODC Code | BODC Units | Unit conversion | Comments |
| depthm | Metres | Sea floor depth (single-beam) | MBANZZ01 | Metres | N/A | - |
Position
A check was run on positional data to identify gaps and improbable values (through the calculation of speed). There were no gaps in the positional data.
Ship Velocities
Ship velocities were calculated from the main latitude and longitude channels using standard BODC procedures.
Distance Run
Distance run was calculated from the latitude and longitude channels, starting from the beginning of the file, using BODC standard procedures.
Bathymetry
Bathymetry data from the EA640 single-beam echo-sounder were screened independently. The EM122 was turned off for the majority of the cruise, potentially to prevent interference with other science activities onboard, and so this channel is not provided.
Calibrations
Field Calibrations
No field calibrations were applied to the data at BODC.
Screening
All reformatted data were visualised using the in-house EDSERPLO software. Suspect data were marked by adding an appropriate quality control flag.
Project Information
Marine LTSS: CLASS (Climate Linked Atlantic Sector Science)
Introduction
CLASS is a five year (2018 to 2023) programme, funded by the Natural Environment Research Council (NERC) and extended until March 2024.
Scientific Rationale
The ocean plays a vital role in sustaining life on planet Earth, providing us with both living resources and climate regulation. The trajectory of anthropogenically driven climate change will be substantially controlled by the ocean due to its absorption of excess heat and carbon from the atmosphere, with consequent impacts on ocean resources that remain poorly understood. In an era of rapid planetary change, expanding global population and intense resource exploitation, it is vital that there are internationally coordinated ocean observing and prediction systems so policy makers can make sound evidence-based decisions about how to manage our interaction with the ocean. CLASS will underpin the UK contribution to these systems, documenting and understanding change in the marine environment, evaluating the impact of climate change and effectiveness of conservation measures and predicting the future evolution of marine environments. Over the five-year period CLASS will enhance the cost-effectiveness of observing systems by migrating them towards cutting edge autonomous technologies and developing new sensors. Finally, CLASS will create effective engagement activities ensuring academic partners have transparent access to NERC marine science capability through graduate training partnerships and access to shipborne, lab based and autonomous facilities, and modelling capabilities.
Data Activity or Cruise Information
Cruise
| Cruise Name | DY103 |
| Departure Date | 2019-06-21 |
| Arrival Date | 2019-07-09 |
| Principal Scientist(s) | Susan E Hartman (National Oceanography Centre, Southampton) |
| Ship | RRS Discovery |
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 |
