Metadata Report for BODC Series Reference Number 1762297


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 Miss Arwen Bargery
Originating Organization British Oceanographic Data Centre, Liverpool
Processing Status banked
Project(s) -
 

Data Identifiers

Originator's Identifier JR20131005_PRODQXF_NAV
BODC Series Reference 1762297
 

Time Co-ordinates(UT)

Start Time (yyyy-mm-dd hh:mm) 2013-10-07 07:51
End Time (yyyy-mm-dd hh:mm) 2013-11-08 13:03
Nominal Cycle Interval 60.0 seconds
 

Spatial Co-ordinates

Southernmost Latitude 51.24900 S ( 51° 14.9' S )
Northernmost Latitude 50.80017 N ( 50° 48.0' N )
Westernmost Longitude 57.11533 W ( 57° 6.9' W )
Easternmost Longitude 0.97200 W ( 0° 58.3' 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}
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 AMT23 JR300 JR20131005 Navigation and Bathymetry Data Quality Document

Navigation and bathymetry

The navigation data have been through BODC quality control screening. Overall the data for the cruise duration appeared good.

The bathymetric data were also quality controlled during BODC screening procedures. There were extensive periods of large-scale noise that hide the real bathymetry in the channel. On these occasions, flags have been applied to the whole section. For time periods where the noise was clearly above or below the bathymetric signal, the data points were flagged as suspect. Users should use caution when interpreting the bathymetric depth channel due to the highly noisy nature of the channel.


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 AMT23 JR300 JR20131005 Navigation and Bathymetry Instrument Description Document

Navigation and bathymetry (HIPLAT)

The navigation instruments used to collect this dataset are displayed in the table below.

Instrument Type Main role
Furuno Loran C Ship's speed and course (over ground)
Seatex Seapath 320+ Ship's position
Sperry Marine Gyro Mk37 Model D Gyrocompass Heading
Simrad Kongsberg EA600 Bathymetry
Chernikeeff Aquaprobe Mk5 Aquaprobe Ship's speed through the 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 AMT23 JR300 JR20131005 Navigation and Bathymetry Processing Procedures 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 and stored in comma separated ACO format. The header information was in TPL files. Each instrument logged data to one individual file. The transfered latitude and lonitude nagivation data originated from the Seatex Seapath 320+ GPS, as this was the best quality positional dataset out of the original files. Bathymetry data originated from the EA600 Kongsberg echo sounder and the ship's orientation originated from the Sperry Marine gyrocompass and Ashtech GPS. The ship's speed and direction over ground came from the Furuno GPS. The speed through water originated from the Chernikeeff Aquaprobe.

The originator's data files exhibited the same common format for the first four columns: Year (yyyy), Julian day.day fraction (days), Julian day (days), day fraction (days). The remaining columns contain the actual data values.

The originator's files that had transferable navigation and bathymetric data were:

The start dates and times of the files are shown in the table below.

Filename Start date Start Time End date End Time
seatex-gga.ACO 07/10/2013 07:50:42 08/11/2013 13:02:43
emlog-vlw.ACO 07/10/2013 7:50:43 08/11/2013 12:59:34
gyro.ACO 07/10/2013 07:50:43 08/11/2013 13:01:44
furuno-vtg.ACO 07/10/2013 07:50:43 08/11/2013 12:59:46
emlog-vhw.ACO 07/10/2013 07:50:44 08/11/2013 13:00:09
ea600.ACO 07/10/2013 10:17:55 08/11/2013 13:01:10

BODC Data Processing

The ACO files provided by the originator were 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.

Originator's file and parameter Units Description BODC parameter Units Comments
seatex-gga.ACO, lat Degrees (+ve N) Latitude north (WGS84) by Seatex Seapath DGPS ALATSP01 Degrees (+ve N) -
seatex-gga.ACO, lon Degrees (+ve E) Longitude east (WGS84) by Seatex Seapath DGPS ALONSP01 Degrees (+ve E) -
- - Distance traveled DSRNCV01 m Channel derived using Matlab routine from Seatex navigation channels
gyro.ACP, heading degrees Orientation (horizontal relative to true north) of measurement platform {heading} by compass HEADCM01 degrees -
- - Eastward velocity (over ground) of measurement platform by unspecified GPS system APEWGP01 cm s -1 Channel derived after transfer using BODC Matlab routine 'velcal'
- - Northward velocity (over ground) of measurement platform by unspecified GPS system APNSGP01 cm s -1 Channel derived after transfer using BODC Matlab routine 'velcal'
ea600.ACO, depth m Sea-floor depth (below instantaneous sea level) {bathymetric depth} in the water body by echo sounder MBANZZ01 m -
furuno-vtg.ACO, sog knots Speed (over ground) of measurement platform by unspecified GPS system APSAGP01 m s -1 * 0.514444
furuno-vtg.ACO, cmg degrees Direction of motion (over ground) of measurement platform {course made good} by unspecified GPS system APDAGP01 degrees -
emlog-vhw.ACO, velocity_f knots Speed (through water) of measurement platform by electromagnetic log APSAWW01 m s -1 * 0.514444

Navigation channels

Latitude and longitude channels were checked and the best quality channels were from the seatex.ACO file. There were only gaps at the start and end of the file.

Distance Run

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

Ship's north and east velocity

The ship's north and east velocities were re-derived using BODC Matlab routine 'velcal'.

Calibrations

No sample or manufacturer's calibrations were applied to the navigation and bathymetry channels by BODC.


Project Information


No Project Information held for the Series

Data Activity or Cruise Information

Cruise

Cruise Name JR20131005 (AMT23, JR300)
Departure Date 2013-10-01
Arrival Date 2013-11-11
Principal Scientist(s)Mikhail V Zubkov (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
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