Metadata Report for BODC Series Reference Number 1760635


Metadata Summary

Data Description

Data Category Bathymetry
Instrument Type
NameCategories
Kongsberg (Simrad) EA600 Echosounder  single-beam echosounders
Ashtech ADU5 Global Positioning System receiver  Differential Global Positioning System receivers
Kongsberg Seatex Seapath 200 Global Positioning System receiver and Gyrocompass  platform attitude sensors; Differential Global Positioning System receivers
Trimble Applanix POSMV global positioning system  Differential Global Positioning System receivers; inertial navigation systems; Kinematic Global Positioning System receivers
Kongsberg Seatex Differential Positioning Sensor 116  Differential Global Positioning System receivers
Sperry Marine NAVIGAT X MK 1 digital gyrocompass  platform attitude sensors
Instrument Mounting research vessel
Originating Country United Kingdom
Originator Dr Andy Rees
Originating Organization Plymouth Marine Laboratory
Processing Status banked
Project(s) Oceans 2025 Theme 10 SO1:AMT
 

Data Identifiers

Originator's Identifier JC039_PRODQXF_NAV
BODC Series Reference 1760635
 

Time Co-ordinates(UT)

Start Time (yyyy-mm-dd hh:mm) 2009-10-13 12:12
End Time (yyyy-mm-dd hh:mm) 2009-11-30 11:06
Nominal Cycle Interval 60.0 seconds
 

Spatial Co-ordinates

Southernmost Latitude 51.59017 S ( 51° 35.4' S )
Northernmost Latitude 50.15783 N ( 50° 9.5' N )
Westernmost Longitude 65.70050 W ( 65° 42.0' W )
Easternmost Longitude 4.99800 W ( 4° 59.9' W )
Positional Uncertainty 0.0 to 0.01 n.miles
Minimum Sensor Depth -
Maximum Sensor Depth -
Minimum Sensor Height -
Maximum Sensor Height -
Sea Floor Depth -
Sensor Distribution -
Sensor Depth Datum -
Sea Floor Depth Datum -
 

Parameters

BODC CODE Rank Units Short Title Title
AADYAA01 1 Days Date(Loch_Day) Date (time from 00:00 01/01/1760 to 00:00 UT on day)
AAFDZZ01 1 Days Time(Day_Fract) Time (time between 00:00 UT and timestamp)
ALATGP01 1 Degrees Lat_GPS Latitude north (WGS84) by unspecified GPS system
ALONGP01 1 Degrees Lon_GPS Longitude east (WGS84) by unspecified GPS system
APEWGP01 1 Centimetres per second PlatformVelE_GPS Eastward velocity (over ground) of measurement platform by unspecified GPS system
APNSGP01 1 Centimetres per second PlatformVelN_GPS Northward velocity (over ground) of measurement platform by unspecified GPS system
DSRNCV01 1 Kilometres Cmpval Distance travelled
HEADCM01 1 Degrees Platform_Heading Orientation (horizontal relative to true north) of measurement device {heading}
MBANCT01 1 Metres BathyDepESCartCorr Sea-floor depth (below instantaneous sea level) {bathymetric depth} in the water body by echo sounder and correction using Carter's tables
 

Definition of Rank

  • Rank 1 is a one-dimensional parameter
  • Rank 2 is a two-dimensional parameter
  • Rank 0 is a one-dimensional parameter describing the second dimension of a two-dimensional parameter (e.g. bin depths for moored ADCP data)

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
2 cm at 120 kHZ
5 cm at 38 kHz
10 cm at 18 kHz
20 cm at 12kHz

Operating frequencies 1 or 2 kHz
Single Beam frequencies

12, 18, 33, 38, 50, 70,
120, 200, 210 or 710 kHz

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:
Antenna
Receiver


-40°C to 65°C
-20°C to 55°C


-40°C to 65°C
-20°C to 55°C

Sampling frequency 5 Hz 5 Hz
Receiver channels 48 56

Accuracy:
Heading
Pitch/Roll


0.2° rms (dynamic) - 0.4° rms (static)
0.4° rms (dynamic) - 0.8° rms (static)


0.02° to 0.2° rms
0.04° to 0.4° rms

Circular Error Probability:
Autonomous
Differential


5.0 m
1.0 m


3.0 m
0.4 to 1.0 m

Further details can be found in the manufacturer's specification sheets for the ADU2 and ADU5 .

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:

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 Channels

Once 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:

The specific objectives are:

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