Metadata Report for BODC Series Reference Number 1760635
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
AMT RRS James Cook Cruise JC039 navigation quality control report
Navigation
The navigation data have been through BODC quality control screening. The gaps of less than ten minutes have been filled by interpolation. Overall the navigation data for the cruise duration appear good. There were 2 periods (6+ hrs) of missing positional data in the RVS bestnav file provided in the Post-Cruise archive. No further recovery of navigation data has been possible for these periods and they have been filled by interpolation. Both these periods appear to be while the vessel was steaming between stations and it could be considered that the interpolated values should be reasonable for use with the underway meteorology and hydrography data.
Bathymetry
The connectivity problems between the logging PC and the transducer resulted in a very noisy stream of bathymetry data. The MBANCT01 channel has been flagged to remove the most obvious suspect data but for many periods the variation was large and frequent. There is no depth data available from 17th November 2009 12:00.
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.
AMT RRS James Cook Cruise JC039 navigation instrumentation
| Manufacturer | Model | Type |
| Ashtech | ADU5 GPS based attitude measuring system | GPS |
| Seatex | Seapath 200 GPS unit | GPS |
| Applanix | POSMV GPS unit | GPS |
| Kongsberg Seatex | DPS116 GPS unit | GPS |
| Sperry Marine | NAVIGAT X MK 1 gyrocompass | Gyrocompass |
| Simrad | EA600 Precision Echo Sounder | Echosounder |
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.
Kongsberg Seatex Differential Positioning Sensor 116
A 14-channel, all-in-view, L1 GPS receiver which primarily utilises the free, WAAS, EGNOS and MSAS Satellite Based Augmentation Systems (SBAS) for differential corrections (DGPS). It is also capable of simultaneous DGPS from a wide variety of other reference stations (Multiref), resulting in improved accuracy. Simultaneous reception and use of correction signals in MF and UHF frequency bands, Inmarsat standard A, B and M terminals and SeaSTAR Spot, are possible.
| Performance | |
| DGPS position accuracy with SBAS service | < 1.5 m, 95% CEP (*) 0.6 m, 1θ (*) |
| DGPS position accuracy (Multiref) | < 1 m, 95% CEP (**) 0.4 m, 1θ (**) |
| Velocity accuracy | 0.05 m/s, 95% CEP (**) 0.02 m/s, 1θ (**) |
| Output rate | 1 Hz |
(*) Accuracy specifications are based on real-life tests conducted using WAAS and an open view to the sky in Houston, Texas.
(**) Accuracy specifications are based on real-life tests conducted under low multipath conditions and an open view to the sky in Trondheim, Norway. Tests at different locations under different conditions may produce different results.
Full specifications can be found here.
Kongsberg Seatex Seapath 200 GPS and Gyrocompass
The Seapath 200 is a highly accurate, real-time heading, attitude and position information system that integrates the best signal characteristics of Inertial Measurement Units (IMU) and Global Positioning System (GPS), using a differential GPS method to acquire this data.
The high-rate motion data is obtained from the Seatex MRU5 inertial sensor and two fixed baseline GPS carrier-phase receivers. The raw data is integrated in a Kalman filter in the Seapath Processing Unit. The IMU contains an accurate linear accelerometer and Bosch Coriolis force angular rate gyros (CFG).
This system is equipped to utilise up to six different DGPS reference stations, it checks for consistency within measurements from the different sensors to ensure reliability and rejects noisy data or reports its inaccuracy. The data is available through various output protocols, RS-232, RS-422 and Ethernet.
This instrument is no longer in production; the main characteristics are presented below, and the specification sheet can be accessed here Kongsberg Seatex Seapath 200 .
Specifications
| Scale factor error in pitch, roll and heading | 0.2% RMS |
| Heave motion periods | 1 to 25 s |
| Accuracy | |
| Heading | 0.05° RMS (4 m baseline) 0.075° RMS (2.5 m baseline) |
| Roll and Pitch | 0.03° EMS (± 5° amplitude) |
| Heave | 5 cm or 5%, whichever is highest |
| Position | 0.7 RMS or 1.5 m (95% CEP) with DGPS 0.15 m EMS or 0.4 m (95% CEP) with Searef 100 corrections |
| Velocity | 0.03 m s-1 RMS or 0.07 m s-1 (95% CEP) with DGPS |
Sperry Marine NAVIGAT X MK 1 digital gyrocompass
A digital gyrocompass for use in marine navigation. The system comprises a gyrosphere supported in fluid, suspended at a single point. The centering pin retaining arrangement can be mounted in an additional gimbal system for high speed applications (Mod 7). The system can drive up to 12 analogue repeaters and has 7 independent serial outputs and 2 dependent 6 steps/° heading outputs. The NAVIGAT X MK1 was the first of the Sperry Marine range of heading sensors, which comprises the NAVIGAT 3000 fibreoptic gyrocompass, the NAVIGAT X MK 1 and the NAVIGAT X MK 2 digital gyrocompasses.
Specifications
| Heading accuracy | <0.1° secant latitude (linear mean settle point error) <0.1° secant latitude (static) <0.4° secant latitude (dynamic) |
| Freedom of pitch and roll | ±40° (Mod 10) ±90° (Mod 7) |
Detailed specifications can be found in the manufacturer's data sheet.
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.
AMT RRS James Cook Cruise JC039 navigation data processing procedures
Originator's Data Processing
During the cruise there was a dual logging system in place on the RRS James Cook. Navigational data from the various GPS instruments were logged to the RVS Level-C system and also as NetCDF (binary) through the Ifremer Techsas data logging system. In addition to the GPS systems the following instruments were logged during the cruise:
1) Chernikeef EM speed log (logged to RVS format as log_chf)
2) Ships Gyrocompass (logged to RVS format as gyro)
3) Simrad EA600 Precision Echo Sounder (logged to RVS format as ea600m)
The TECHSAS files were processed using the RVS software suite. The following routines were run on the navigation and bathymetry data channels to produce files named after the routine that generated them:
- RELMOV - Relmov is the relative motion file for this cruise. This was generated using the ships gyro and ships Chernikeef Log data to extract a movement in a given direction. This was then used by bestnav when and where necessary to calculate fixes if GPS fixes were not available.
- BESTNAV - Bestnav uses all 3 GPS Systems logged and creates a best suite stream by providing an as complete account of the ships track as possible. This is done by reading all 3 GPS streams with gps_g2 being primary, gps_4000 as secondary and gps_ash as tertiary. The system looks for gaps of a certain length in the primary and when it finds those gaps it requests that the next gps down fill in the gaps. If no GPS data is available it asks RELMOV to fill in until data is available again. Then the system calculates back over itself to ensure that the extrapolated positions are correct using the GPS data available around the gap.
- BESTDRF - Bestdrf is a product of bestnav. When run bestnav uses the relmov data which contains a predicted vn and ve based upon direction and speed through the water. The Bestdrf file is the accurate drift velocity of what actually occurred based on the GPS changes between each record.
- PRODEP - Prodep is an automated process that accessed the bestnav position fix data and then uses a pre programmed Carter tables of corrections and corrects the echo sounder data for that given location.
The Simrad-EA600 had several issues during the cruise where it lost network connection between the PC and its Transceiver unit which controls, powers and interprets the return signals from the transducer. Kongsberg were contacted and after several days of the unit falling over it was recommended that the software be upgraded. The upgrade featured a GPT Firmware update. This update failed and the Transceiver PIC was damaged. The GPT could not be used again. No useable data were recorded from 17th November 2009 onwards. The EA500 was then used for general echo sounding but the data was not recorded.
The table below shows details of the original files delivered to BODC.
| Filename | Content Description | Format | Start Calendar Day | Start Time | Finish Calendar Day | Finish Time | Data Interval |
| bestnav | Best determined position | RVS Level-C processed | 2009-10-13 | 12:11:50 | 2009-11-30 | 11:06:10 | 10 seconds |
| prodep | Sea floor depth corrected using Carter tables | RVS Level-C processed | 2009-10-13 | 12:30:02 | 2009-11-17 | 14:30:02 | 6-7 seconds |
BODC Data Processing
Reformatting
Navigation and bathymetry from processed RVS format files were transferred to BODC's NetCDF format (QXF) under the BODC Underway Data System (BUDS). This transfer involved reducing the data by averaging to 60 second intervals. Directional data were reduced by averaging using a unit circle.
The ship's primary GPS system for scientific data and also part of the Dynamic Positioning System is the Applanix POSMV. Data from the bestnav file were transferred and used as the source for cruise navigation data.
The originator's variables were mapped to the appropriate codes as follows:
bestnav
| Originators Variables | Originators Units | Description | BODC Parameter Code | BODC Units | Conversion Factor | Comments |
| lat | Degrees +ve N | Latitude | ALATGP01 | Degrees +ve N | *1 | |
| lon | Degrees +ve E | Longitude | ALONGP01 | Degrees +ve E | *1 | |
| vn | knots | northwards velocity | APNSGP01 | cm s-1 | *51.44 | |
| ve | knots | eastwards velocity | APEWGP01 | cm s-1 | *51.44 | |
| mode | mode that the GPS was operating in. 0 indicates an invalid fix, 1 a GPS fix and 2 a DGPS fix | channel not transferred | ||||
| cmg | Degrees True | Course made good | Degrees True | *1 | channel not transferred | |
| smg | knots | Speed made good | m s-1 | *0.514 | channel not transferred | |
| dist_run | Nautical miles | Distance run | DSRNCV01 | km | *1.852 | |
| Heading | Degrees true | Ship's heading | HEADCM01 | Degrees true | *1 |
prodep
| Originators Variables | Originators Units | Description | BODC Parameter Code | BODC Units | Conversion Factor | Comments |
| uncdepth | Raw depth from echosounder | channel not transferred | ||||
| cordepth | m | Depth corrected from Carter's tables | MBANCT01 | m | *1 | |
| cartarea | Carter's table area from position | channel not transferred |
Data Processing
Navigation ChannelsOnce the data in the RVS navigation file 'bestnav' were transferred to the BODC QXF format, a Matlab program ('navcheck') 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. There were a few small gaps (<5 minutes) in the latitude and longitude channels, these were filled using the Matlab program 'navint' to interpolate data to fill the gaps. In addition the 'navcheck' routine checked the vessel's speed over the ground from the navigation data for values that are outside an expected range.
Screening
The latitude and longitude channels were screened by plotting the course on to a map of the Atlantic Ocean. There was no further flagging required as there were no warnings indicated by the 'navcheck' routine.
Each data channel was inspected on a graphics workstation using BODC screening software EDSERPLO and any spikes or periods of dubious data were flagged using BODC quality control flag system. Impossible values were checked carefully and flagged null only if believed to be genuine missing or bad data. EDSERPLO 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.
Calibrations
No field or manufacturer's calibrations were applied to the data at BODC.
Project Information
Oceans 2025 Theme 10, Sustained Observation Activity 1: The Atlantic Meridional Transect (AMT)
The Atlantic Meridional Transect has been operational since 1995 and through the Oceans 2025 programme secures funding for a further five cruises during the period 2007-2012. The AMT programme began in 1995 utilising the passage of the RRS James Clark Ross between the UK and the Falkland Islands southwards in September and northwards in April each year. Prior to Oceans 2025 the AMT programme has completed 18 cruises following this transect in the Atlantic Ocean. This sustained observing system aims to provide basin-scale understanding of the distribution of planktonic communities, their nutrient turnover and biogenic export in the context of hydrographic and biogeochemical provinces of the North and South Atlantic Oceans.
The Atlantic Meridional Transect Programme is an open ocean in situ observing system that will:
- give early warning of any fundamental change in Atlantic ecosystem functionng
- improve forecasts of the future ocean state and associated socio-economic impacts
- provide a "contextual" logistical and scientific infrastructure for independently-funded national and international open ocean biogeochemical and ecological research.
The specific objectives are:
- To collect hydrographic, chemical, ecological and optical data on transects between the UK and the Falkland Islands
- To quantify the nature and causes of ecological and biogeochemical variability in planktonic ecosystems
- To assess the effects of variability in planktonic ecosystems on biogenic export and on air-sea exchange of radiatively active gases
The measurements taken and experiments carried out on the AMT cruises will be closely linked to Themes 2 and 5. The planned cruise track also allows for the AMT data to be used in providing spatial context to the Sustained Observation Activities at the Porcupine Abyssal Plain Ocean Observatory (SO2) and the Western Channel Observatory (SO10).
More detailed information on this Work Package is available at pages 6 - 9 of the official Oceans 2025 Theme 10 document: Oceans 2025 Theme 10
Weblink: http://www.oceans2025.org/
Data Activity or Cruise Information
Cruise
| Cruise Name | JC039 (AMT19, JC040) |
| Departure Date | 2009-10-13 |
| Arrival Date | 2009-12-01 |
| Principal Scientist(s) | Andrew Rees (Plymouth Marine Laboratory) |
| Ship | RRS James Cook |
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 |
