Metadata Report for BODC Series Reference Number 2021651
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
JR18002 Navigation quality control report
Bathymetry
Bathymetry data from the EA600 singlebeam channel are of moderate quality where flags have been applied to approximately 45% of the data. Despite following GEBCO?s trend quite well, periods of noise occur frequently within the dataset and these were flagged accordingly.
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.
JR18002 underway navigation instrumentation
The following scientific navigational and bathymetric systems were fitted.
Manufacturer | Model | Function | Comments |
Seatex | Seapath 320+ | GPS (latitude, longitude,speed over ground and course over ground) | Primary source of position for science. |
Kongsberg Maritime | Simrad EA600 | Single-beam echo sounder (hull) | Primary bathymetry source. |
Kongsberg Maritime | Simrad EM122 | Multi-beam echo sounder (deep) | Switched off for the duration of the cruise |
Sperry Marine | MK37 series gyrocompasses | GPS (ships heading) |
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.
JR18002 Underway Navigation Processing Procedures Document
Originator's Data Processing
The navigation data and bathymetric data were measured by different instruments during the cruise, with each instrument logging data to comma separated ASCII .ACO files using the SCS data logging software. The data were stored in the .ACO files and header information was stored in the corresponding .TPL files.
Data were processed by the originator using the National Oceanography Centre MSTAR data processing routines into NetCDF files. These MSTAR (NetCDF) files were provided to BODC and used for BODC processing. The EM122 was set not to log any data as the SR1b track had been traversed many times. The EA600 single-beam echo-sounder was run throughout the cruise but it was not examined by the originator. Please refer to page 68 of the cruise report for more information.
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/time (UTC) | End date/time (UTC) | Comments |
bst_jr18002_01.nc | Position, heading, speed and course over ground | NetCDF | 30 seconds | 31/10/2018 14:31:00 | 21/11/2018 11:37:30 | - |
ea600.ACO | bathymetry data from EA600 | ASCII | 6-8 seconds | 30/10/2018 15:18:55 | 21/11/2018 17:24:49 | Omitted from originator's NetCDF file. Added from SCS .ACO file for source of bathymetry |
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:
bst_jr18002_01.nc
Originator's variable | Originator's units | Description | BODC Code | BODC Units | Unit conversion | Comments |
lat | degrees | Latitude North | ALATGP01 | degrees | N/A | - |
long | degrees | Longitude East | ALONGP01 | degrees | N/A | - |
heading_av_corrected | degrees | Heading (corrected) | HEADCM01 | degrees | N/A | - |
smg | m/s | Speed over ground | APSAGP01 | m/s | N/A | - |
cmg | degrees | Course over ground | APDAGP01 | degrees | N/A | - |
ea600.ACO
Originator's variable | Originator's units | Description | BODC Code | BODC Units | Unit conversion | Comments |
depth | metres | Sea floor depth (single-beam) | MBANZZ01 | metres | N/A | - |
All reformatted data were visualised using the in-house EDSERPLO software. Where calibrations had been applied, only the calibrated versions of those parameters were screened. Suspect data were marked by adding an appropriate quality control flag.
Position
A check was run on positional data to identify gaps and improbable values (through the calculation of speed). There was one gap in the positional data at the start and end of the file, produced during loading to the BODC system. These gaps were trimmed after processing was complete.
Distance Run
Distance run was calculated from the main latitude and longitude channels, starting from the beginning of the file, using BODC standard procedures.
GEBCO
GEBCO bathymetry (15 arc-second grid) was added to the file using the main latitude and longitude channels. It was used to screen echo-sounder bathymetry.
Bathymetry
Bathymetry data were screened independently as well as against GEBCO bathymetry measurements. The EA600 was the only source of bathymetric data during JR18002.
Calibration
No field calibrations were applied to the data at BODC.
Project Information
Ocean Regulation of Climate by Heat and Carbon Sequestration and Transports (ORCHESTRA)
The Ocean Regulation of Climate by Heat and Carbon Sequestration and Transports (ORCHESTRA) is a £8.4 million, five year (2016-2021) research programme funded by the Natural Environment Research Council (NERC). The aim of the research is to to advance the understanding of, and capability to predict, the Southern Ocean's impact on climate change via its uptake and storage of heat and carbon. The programme will significantly reduce uncertainties concerning how this uptake and storage by the ocean influences global climate, by conducting a series of unique fieldwork campaigns and innovative model developments.
Background
ORCHESTRA represents the first fully-unified activity by NERC institutes to address these challenges, and will draw in national and international partners to provide community coherence, and to build a legacy in knowledge and capability that will transcend the timescale of the programme itself.
It brings together science teams from six UK research institutions to investigate the role that the Southern Ocean plays in our changing climate and atmospheric carbon draw-down. It is led by British Antarctic Survey, in partnership with National Oceanography Centre, British Geological Survey, Plymouth Marine Laboratory, the Centre for Polar Observation and Modelling and the Sea Mammal Research Unit.
The oceans around Antarctica play a critical a key role in drawing down and storing large amounts of carbon and vast quantities of heat from from the atmosphere. Due to its remoteness and harsh environment, the Southern Ocean is the world's biggest data desert, and one of the hardest places to get right in climate models. The ORCHESTRA programme will make unique and important new measurements in the Southern Ocean using a range of techniques, including use of the world-class UK research vessel fleet, and deployments of innovative underwater robots. The new understanding obtained will guide key improvements to the current generation of computer models, and will enhance greatly our ability to predict climate into the future.
The scope of the programme includes interaction of the Southern Ocean with the atmosphere, exchange between the upper ocean mixed layer and the interior and exchange between the Southern Ocean and the global ocean.
Further details are available on the ORCHESTRA page.
Participants
Six different organisations are directly involved in research for ORCHESTRA. These institutions are:
- British Antarctic Survey (BAS)
- National Oceanography Centre (NOC)
- Plymouth Marine Laboratory (PML)
- British Geological Survey (BGS)
- Centre for Polar Observation and Modelling (CPOM)
- Sea Mammal Research Unit (SMRU)
GO-SHIP are a third party organisation that, although not directly involved with the programme, will conduct ship based observations that will also be used by ORCHESTRA.
Research details
Three Work Packages have been funded by the ORCHESTRA programme. These are described in brief below:
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Work Package 1: Interaction of the Southern ocean with the atmosphere
WP1 will use new observations of surface fluxes and their controlling parameters in order to better constrain the exchanges of heat and carbon loss across the surface of the Southern Ocean. -
Work Package 2: Exchange between the upper ocean mixed layer and the interior.
This work package will combine observationally-derived data and model simulations to determine and understand the exchanges between the ocean mixed layer and its interior. -
Work Package 3: Exchange between the Southern Ocean and the global ocean .
This WP will use budget analyses of the hydrographic/tracer sections to diagnose the three-dimensional velocity field of the waters entering, leaving and recirculating within the Southern Atlantic sector of the Southern ocean. -
Fieldwork and data collection
The campaign consists of 12 core cruises on board the NERC research vessels RRS James Clark Ross and RRS James Cook and will include hydrographic/tracer sections conducted across Drake Passage (SR1b), the northern Weddell Sea/Scotia Sea (A23), the northern rim of the Weddell Gyre (ANDREXII) and across the South Atlantic (24S). Section I6S will be performed by GO-SHIP Project Partners. Measurements will include temperature, salinity, dissolved oxygen, velocity, dissolved inorganic carbon, total alkalinity, inorganic nutrients, oxygen and carbon isotopes, and underway meteorological and surface ocean observations including pCO2.
Tags will be deployed on 30 Weddel seals and these will provide temperature and salinity profiles that can be used alongside the Argo data.
Autonomous underwater ocean gliders will conduct multi-month missions and will deliver data on ocean stratification, heat content, mixed layer depth and turbulent mixing over the upper 1 km, with previously-unobtainable temporal resolution. These gliders will be deployed in the Weddell Gyre and the ACC.
Field campaigns with the MASIN meteorological aircrafts will be conducted flying out of Rothera and Halley research stations and the Falkland Islands. These campaigns will deliver information on key variables relating to air-sea fluxes (surface and air temperature, wind, humidity, atmospheric CO2, radiation, turbulent fluxes of heat, momentum and CO2), in different sea ice conditions and oceanic regimes.
Eart Observation datasets will be used to inform the programme on the properties of the ocean, sea ice and atmosphere and on interactions between them.
A cluster of 6 deep ocean moorings in the Orkney Passage will collect year round series of AABW temperatre and transport. This work connects to the NERC funded project Dynamics of the Orkney Passage Outflow (DYNOPO).
The UK Earth System model (UKESM) and underlying physical model will be used to conduct analyses of heat and carbon uptake and transport by the Southern Ocean and their links to wider climate on decadal timescales.
An eddy-resolving (1/12°) sector model of the ocean south of 30°S with 75 vertical levels, will be built using the NEMO model coupled to the Los Alamos sea ice (CICE) model. The improvements on the ocean boundary layer will be based from the results from the NERC-funded OSMOSIS project and the inclusion of tides.
20-5 year runs of an adjoint model will be conducted to determine how key forcings and model states affect the uptake and subduction of heat and carbon by the ocean.
Data Activity or Cruise Information
Cruise
Cruise Name | JR18002 |
Departure Date | 2018-11-03 |
Arrival Date | 2018-11-22 |
Principal Scientist(s) | Yvonne L Firing (National Oceanography Centre, Southampton) |
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 |
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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 |