Metadata Report for BODC Series Reference Number 1749246

Metadata Summary

Data Description

Data Category Bathymetry
Instrument Type
Simrad EA500 echosounder  single-beam echosounders
Fugro SeaSTAR 9200-G2 Differential Navigation System receiver  Differential Global Positioning System receivers
Ashtech ADU2 Global Positioning System receiver  NAVSTAR Global Positioning System receivers
Sperry Marine MK37 series gyrocompasses  platform attitude sensors
Trimble 4000DS Global Positioning System receiver  Differential Global Positioning System receivers
Instrument Mounting research vessel
Originating Country United Kingdom
Originator Mr Martin Bridger
Originating Organization National Marine Facilities Sea Systems
Processing Status banked
Project(s) UKOARP_ThemeB

Data Identifiers

Originator's Identifier D366_PRODQXF_NAV
BODC Series Reference 1749246

Time Co-ordinates(UT)

Start Time (yyyy-mm-dd hh:mm) 2011-06-06 08:08
End Time (yyyy-mm-dd hh:mm) 2011-07-09 12:55
Nominal Cycle Interval 60.0 seconds

Spatial Co-ordinates

Southernmost Latitude 45.36083 N ( 45° 21.6' N )
Northernmost Latitude 60.00283 N ( 60° 0.2' N )
Westernmost Longitude 12.02200 W ( 12° 1.3' W )
Easternmost Longitude 10.01383 E ( 10° 0.8' 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 -


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

UK Ocean Acidification RRS Discovery Cruise D366 Underway Navigation and Bathymetry Data Quality Report


The navigation data channels (ALATGP01 and ALONGP01) have been through BODC quality control screening. Three gaps of less than ten minutes have been filled by interpolation. Overall the data for the cruise duration appear good.


The bathymetric data channel has been through BODC quality control screening. There are extensive periods of large-scale noise that hide the real bathymetry in the channel. Where possible some periods have been flagged to remove the noise. Users should use caution when interpreting the bathymetric depth 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 Simrad EA500 bathymetric echosounder

The EA500 is a bathymetric echosounder that can be used in water as deep as 10,000 m. It features triple frequency operation with a separate digitiser for each channel and high transmitted power with an instantaneous dynamic range of 160 dB. The instrument can operate with several pulses in the water simultaneously and has bottom tracking capabilities. A wide range of transducers (single beam, split beam or side-looking) is available and the ping rate is adjustable up to 10 pings per second. The split beam operation measures the athwartships inclination angle of the seabed.

This instrument was introduced in June 1989 and and replaced by the EA 600 in 2000.


Operational range 1, 5, 10, 15, 25, 50, 100, 150, 250, 500, 750, 1000, 2500, 5000 and 10000 m
Phasing 0 to 10000 m in 1 m increments (manual or automatic)
Non saturated instantaneous input range -160 to 0 dB
Output power regulation 0 to 20 dB relative to full power
Noise figure 10 dB
Operating temperature 0 to 55°C
Ping rate max 10 pings per second (adjustable)

Further details can be found in the manufacturer's specification sheet .

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.


Parameter ADU2 ADU5

Operational Temperature range:

-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


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:

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 .

Fugro SeaSTAR 9200-G2 Receiver

The SeaSTAR 9200-G2 is a dual frequency (L1/L2) receiver that incorporates global positioning system (GPS) and global navigation satellite system (GLONASS) reception capability while tracking the Fugro L-Band satellite broadcast of Differential Global Satellite Navigation System (DGSNS) corrections. These corrections can also be received via internet, as a backup.

The SeaSTAR 9200-G2 can be used in conjunction with other services as HP (GPS network solution), XP (GPS or orbit and clock solution) and G2 (Composite GPS/GLONASS orbit and clock solution). These are also dual frequency carrier phase solutions, which allows for a decimeter level accuracy.

The 72 channels received by the SeaSTAR include GPS- L1 C/A code and L1/L2/L2C full cycle carrier, GLONASS- L1/L2 full cycle carrier, Satellite Based Augmentation System (SBAS) and the Fugro L-Band service.


Position Accuracy Horizontal Vertical
HP 10 cm (95%) 15 cm (95%)
XP 15 cm (95%) 20 cm (95%)
G2 15 cm (95%) 20 cm (95%)

Further details can be found in the manufacturer's specification sheet .

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 .

Trimble 4000DS Global Positioning System receiver

The Trimble 4000DS Differential Surveyor is similar to the 4000RS (a Maxwell-based receiver that is oriented toward precision positioning applications. It is intended for use as a DGPS base station, generating RTCM-104 corrections). The 4000Ds can apply RTCM-104 corrections to the satellite data it receives in order to generate accurate position fixes in real time.

UK Ocean Acidification RRS Discovery Cruise D366 Underway Navigation and Bathymetry Instrumentation

The instruments used to collect the navigation and bathymetry datasets are displayed in the table below.

Instrument Type
Fugro Seastar 9200 G2 XP Differential GPS
Trimble GPS 4000 DS Surveyor GPS
ASHTECH ADU-2 Altitude Detection Unit GPS
Ship's Gyrocompass Gyro compass
Simrad EA500 Precision Echo Sounder Echosounder

UK Ocean Acidification RRS Discovery Cruise D366 Underway Navigation and Bathymetry Data Processing Document

Originator's Data Processing

During the cruise there was a dual logging system in place on the RRS Discovery. Data from the various instruments were logged to the RVS Level-C system (Sun Solaris 10 UNIX Workstation discovery1) and also as NetCDF (binary) through the Ifremer Techsas data logging system.

Processing was carried out 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:

Files delivered to BODC

Filename Data type Start Calendar Day Start Time Finish Calendar Day Finish Time Data Interval
bestnav RVS Level-C processed 2011-06-06 08:08:50 2011-07-09 12:55:40 10 seconds
prodep RVS Level-C processed 2011-06-06 09:07:42 2011-07-09 12:17:26 variable
gps_g2 RVS Level-C raw 2011-06-06 08:08:48 2011-07-09 12:55:53 1 sec
gyro RVS Level-C raw 2011-06-06 08:08:47 2011-07-09 12:55:52 1 sec

BODC Data Processing


The RVS files were transferred into internal BODC format by merging the files into a single binary file using time as the primary linking key. The time span of the file was from 06/06/2011 08:08:50 to 09/07/2011 12:55:50, with a sampling interval of 60 seconds.

The originator's variables were mapped to appropriate BODC parameter codes as follows:


Channels Description Units BODC Parameter Code Units Conversion Factor
heading Ship's heading Degrees true HEADCM01 Degrees true *1


Channels Description Units BODC Parameter Code Units Conversion Factor
lat latitude Degrees ALATGP01 Degrees *1
lon longitude Degrees ALONGP01 Degrees *1
vn Northwards velocity knots APNSGP01 cm s -1 *51.44
ve Eastwards velocity knots APEWGP01 cm s -1 *51.44
cmg Course made good Degrees APDAGP01 - channel not transferred Degrees *1
smg Speed made good Knots APSAGP01 - channel not transferred m s -1 *0.514
dist_run Distance run Nautical miile DSRNCV01 km *1.852
heading Ship's heading Degrees HEADCMMG - dropped after screening Degrees *1


Channels Description Units BODC Parameter Code Units Conversion Factor
uncdepth Raw depth from echosounder m MBANZZ01 - dropped after screening m *1
cordepth Depth corrected from Carter's tables m MBANCT01 m *1
cartarea Carter's table area from position - not for transfer - -


Each data channel was inspected on a graphics workstation and any spikes or periods of dubious data were flagged. The power of the workstation software 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.

Data Processing

Navigation channels

Both the bestnav and gp_g2 data channels were transferred to BODC format and comparison of the channels indicated the bestnav channel was of better quality. The bestnav navigation channels were checked using BODC Matlab routine 'navcheck' and one gap of nine minutes was identified. The gap was removed by interpolating the data using BODC Matlab routine 'navint'. There were no speed check failures. The latitude (ALATGP01) and longitude (ALONGP01) channels were screened though no further flags were applied.

Velocity and distance run channels

The north-south (APNSGP01) and east-west (APEWGP01) ship's velocities were calculated from the latitude and longitude using the BODC Matlab routine 'velcal'. Distance run (DSRNCV01) was then calculated using the BODC Matlab routine 'disrun'.


No calibration against sample data or manufacturer's calibrations were applied to the navigation channels.

Project Information

UKOARP Theme B: Ocean acidification impacts on sea surface biology, biogeochemistry and climate

The overall aim of this theme is to obtain a quantitative understanding of the impact of ocean acidification (OA) on the surface ocean biology and ecosystem and on the role of the surface ocean within the overall Earth System.

The aims of the theme are:

The main consortium activities will consist of in-situ measurements on three dedicated cruises, as well as on-deck bioassay experiments probing the response of the in-situ community to elevated CO2. Most of the planned work will be carried out on the three cruises to locations with strong gradients in seawater carbon chemistry and pH; the Arctic Ocean, around the British Isles and the Southern Ocean.


Data Activity or Cruise Information


Cruise Name D366 (D367)
Departure Date 2011-06-06
Arrival Date 2011-07-09
Principal Scientist(s)Eric Pieter Achterberg (University of Southampton School of Ocean and Earth Science)
Ship RRS Discovery

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