Metadata Report for BODC Series Reference Number 1762328


Metadata Summary

Data Description

Data Category Bathymetry
Instrument Type
NameCategories
Kongsberg (Simrad) EA600 Echosounder  single-beam echosounders
Kongsberg Seatex Seapath 320+ Precise Heading, Attitude and Positioning Sensor  Global Navigation Satellite System receivers; Differential Global Positioning System receivers; inertial navigation systems
Sperry Marine MK37 series gyrocompasses  platform attitude sensors
Instrument Mounting research vessel
Originating Country United Kingdom
Originator Dr Rob Thomas
Originating Organization British Oceanographic Data Centre, Liverpool
Processing Status banked
Project(s) -
 

Data Identifiers

Originator's Identifier JR20140922_PRODQXF_NAV
BODC Series Reference 1762328
 

Time Co-ordinates(UT)

Start Time (yyyy-mm-dd hh:mm) 2014-09-22 20:10
End Time (yyyy-mm-dd hh:mm) 2014-11-02 13:01
Nominal Cycle Interval 60.0 seconds
 

Spatial Co-ordinates

Southernmost Latitude 51.69167 S ( 51° 41.5' S )
Northernmost Latitude 53.63400 N ( 53° 38.0' N )
Westernmost Longitude 57.83000 W ( 57° 49.8' W )
Easternmost Longitude 1.93000 E ( 1° 55.8' E )
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}
MBANZZ01 1 Metres BathyDepES_ISL Sea-floor depth (below instantaneous sea level) {bathymetric depth} in the water body by echo sounder
 

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

RRS James Clark Ross Cruise AMT24 (JR20140922) Navigation and Bathymetry Data Quality Document

Navigation channels

Care should be taken regarding the positional information from 26/10/2014 01:22:00 to 26/10/2014 10:28:00. This is because the navigation sensors did not provide any data during this period with no reliable information available in the bridge log either. Data from an external source were inserted and flagged in order to provide additional complementary information to the Seapath 320+.


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 .

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

RRS James Clark Ross Cruise AMT24 (JR20140922) Navigation and Bathymetry Instrument Description Document

Instrumentation

The following instruments were used to generate the navigation and bathymetry dataset.

Manufacturer Model Main function Serial Number Comments
Seatex Seapath 320+ Position (Latitude and Longitude) - -
Sperry Marine Mk37 Model D Heading - -
Kongsberg Maritime EM122 12 kHz multi-beam echosounder Bathymetry - -
Simrad Kongsberg EA600 single-beam echosounder Bathymetry - -
EMlog possibly (Chernikeef Aquaprobe) Mk5 Aquaprobe Ship's speed through water - -

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 .

RRS James Clark Ross Cruise AMT24 (JR20140922) Navigation and Bathymetry 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 SCS system. Each instrument logged data to one individual in comma separated ACO format file and the header information was stored in corresponding TPL files. 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. The best quality bathymetry data were obtained from the EM122 Kongsberg Maritime multi-beam echo-sounder. The ship's orientation comes from the Sperry Marine Mk 37 gyrocompass. The ship's speed and direction over ground was calculated from the positional data during processing of the data.

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 Start Time End Date End Time
seatex-gga.ACO Latitude and Longitude ASCII (.ACO) 1 Hz 11/09/2014 12:37:39 02/11/2014 15:47:52
gyrocompass.ACO Heading ASCII (.ACO) 1 Hz 11/09/2014 12:37:39 02/11/2014 15:47:53
em122.ACO Multibeam Echosounder ASCII (.ACO) ~2 Hz 25/09/2014 11:42:28 29/09/2014 17:48:21
ea600.ACO Singlebeam Echosounder ASCII (.ACO) 1 Hz 11/09/2014 12:37:38 02/11/2014 14:05:27
emlog-vhw.ACO Speed through water ASCII (.ACO) ~2 Hz 11/09/2014 12:37:40 02/11/2014 15:47:52

BODC Data Processing

The ACO files provided by the originator were archived at BODC and 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. All files were averaged to 60 second intervals.

Originator's File Originator's Parameter Originator's Units Description BODC parameter code BODC units Comments and unit conversions
seatex-gga.ACO lat Degrees (+ve N) Latitude north (WGS84) by Seatex Seapath DGPS ALATGP01 Degrees (+ve N) -
seatex-gga.ACO lon Degrees (+ve E) Longitude east (WGS84) by Seatex Seapath DGPS ALONGP01 Degrees (+ve N) -
- - - Distance traveled DSRNCV01 meters Channel derived using Matlab routine from Seatex navigation channels
gyro.ACO heading degrees Orientation (horizontal relative to true north) of measurement platform {heading} by compass HEADCM01 degrees -
- - - Northward velocity (over ground) of measurement platform by unspecified GPS system APNSGP01 Centimetres per second Channel derived after transfer using BODC Matlab routine 'velcal'
- - - Eastward velocity (over ground) of measurement platform by unspecified GPS system APEWGP01 Centimetres per second Channel derived after transfer using BODC Matlab routine 'velcal'
seatex-vtg.ACO cmg degrees Direction of motion (over ground) of measurement platform {course made good} APDAZZ01 Degrees True -
seatex-vtg.ACO sog knots Speed (over ground) of measurement platform APSAZZ01 Metres per second *0.154444
em122.ACO depth metres Sea-floor depth (below instantaneous sea level) {bathymetric depth} in the water body by multibeam echo sounder central beam MBANSWCB Metres There is only data for a short period after the ship left the UK.
ea600.ACO depth metres Sea-floor depth (below instantaneous sea level) {bathymetric depth} in the water body by echo sounder MBANZZ01 Metres -
seatex-vtg.ACO velocity_f knots Speed (over ground) of measurement platform APSAWW01 Metres per second *0.154444

Derived channels

Distance run was derived using the seatex latitude and longitude channels using the BODC Matlab function 'disrun'.

Ship's north and east velocity channels were derived using the seatex latitude and longitude channels, using the BODC Matlab function 'velcal'.

Sample Calibration

No sample calibrations were applied to these data.


Project Information


No Project Information held for the Series

Data Activity or Cruise Information

Cruise

Cruise Name JR20140922 (AMT24, JR303)
Departure Date 2014-09-22
Arrival Date 2014-11-01
Principal Scientist(s)Tim Smyth (Plymouth Marine Laboratory)
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