Metadata Report for BODC Series Reference Number 1044326

Metadata Summary

Data Description

Data Category Bathymetry
Instrument Type
Simrad EA500 echosounder  single-beam echosounders
Trimble 4000AX Global Positioning System receiver  NAVSTAR Global Positioning System receivers
Instrument Mounting research vessel
Originating Country United Kingdom
Originator Dr Sheldon Bacon
Originating Organization National Oceanography Centre, Southampton
Processing Status banked
Online delivery of data Download available - Ocean Data View (ODV) format
Project(s) Rapid Climate Change Programme

Data Identifiers

Originator's Identifier D298_PRODQXF_NAV
BODC Series Reference 1044326

Time Co-ordinates(UT)

Start Time (yyyy-mm-dd hh:mm) 2005-08-25 02:07
End Time (yyyy-mm-dd hh:mm) 2005-09-21 00:01
Nominal Cycle Interval 120.0 seconds

Spatial Co-ordinates

Start Latitude 55.76650 N ( 55° 46.0' N )
End Latitude 57.86390 N ( 57° 51.8' N )
Start Longitude 4.86310 W ( 4° 51.8' W )
End Longitude 36.23510 W ( 36° 14.1' W )
Positional Uncertainty 0.0 to 0.01 n.miles
Minimum Sensor or Sampling Depth -
Maximum Sensor or Sampling Depth -
Minimum Sensor or Sampling Height -
Maximum Sensor or Sampling Height -
Sea Floor Depth -
Sea Floor Depth Source -
Sensor or Sampling Distribution -
Sensor or Sampling Depth Datum -
Sea Floor Depth Datum -


BODC CODERankUnitsTitle
AADYAA011DaysDate (time from 00:00 01/01/1760 to 00:00 UT on day)
AAFDZZ011DaysTime (time between 00:00 UT and timestamp)
ALATGP011DegreesLatitude north relative to WGS84 by unspecified GPS system
ALONGP011DegreesLongitude east relative to WGS84 by unspecified GPS system
APDAAS011Degrees TrueDirection of motion of measurement platform relative to ground surface {course made good} by Ashtech GPS
APEWGP011Centimetres per secondEastward velocity of measurement platform relative to ground surface by unspecified GPS system
APNSGP011Centimetres per secondNorthward velocity of measurement platform relative to ground surface by unspecified GPS system
DSRNCV011KilometresDistance travelled
HEADCM011DegreesOrientation (horizontal relative to true north) of measurement device {heading}
MBANCT011MetresSea-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

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.

RAPID Cruise D298 Underway Navigation and Bathymetry Instrumentation

There are four GPS receivers on RRS Discovery: the Trimble 4000, which is a differential GPS; the Glonass, which uses a combination of Russian and American satellite networks; the Ashtech; and the SeaStar G12.

Two sources of bathymetric data were available on this cruise; a Precision Echosounding (PES) hull mounted fish transducer; and a Simrad EA500 hydrographic echosounder.

RAPID Cruise D298 Underway Meteorology, Surface Hydrography and Navigation Series

Cruise Details

Dates 23 August - 25 September 2005
Principal Scientific Officer Dr Sheldon Bacon (NOC,S)
Cruise Report Bacon, S. and et al., 2006. RRS Discovery Cruise 298, 23 Aug-25 Sep 2005. Cape Farewell and Eirik Ridge (CFER-1). Southampton, UK, National Oceanography Centre Southampton, 113pp. (National Oceanography Centre Southampton Cruise Report, 10).

D298 was conducted in the vicinty of Cape Farewell, southern Greenland, during early autumn 2005. The main priority of the cruise was to complete a number of mooring operations, but this work was combined with additional hydrographic survey work, sediment coring and sub-bottom profiling.

Data Processing Procedures

Underway sea surface hydrography, meteorology and ship's navigation data are merged into common files using time (UTC) as the primary linking key. Any additional data calibrations are applied as appropriate and are discussed in the individual instrument sections.

Data were transferred to BODC's in-house NetCDF format, QXF, through the BODC Underway Data System (BUDS). During transfer data were time averaged to 120 second intervals. The transfer process also includes the flagging of data which fall outside of the range of acceptable values for each parameter.

Each data channel is visually inspected on a graphics workstation and any spikes or periods of dubious data are flagged as suspect. The capabilities of the workstation screening software allows all possible comparative screening checks between channels. The system also has the facililty of simultaneously displaying the data and the ship's position on a map to enable data screening to take oceanographic climatology into account.

RAPID Cruise D298 Underway Navigation and Bathymetry Processing

Originator's processing

Although all four navigation streams were logged during the cruise, navigation data were obtained from the preferred Trimble 4000 GPS receiver and, where gaps occurred, from Glonass. These data were processed via the PSTAR 'bestnav' procedure. A major problem occurred with the master clock signal used by all navigation streams which was corrected, however there may be still be problems for data before 30th August 2005.

Bathymetric depth by towed fish echosounder was preferred by the originator over the Simrad EA500 echosounder. The data were corrected onboard using Carters tables.

Data were transferred from the raw RVS format to PSTAR format using unix command scripts and compiled into 2 minute averages.

BODC processing

Navigation was checked for gaps and improbable ship speeds at BODC. No improbable speeds were found. Any gaps were linearly interpolated to provide a continuous data record.

Distance run was calculated using latitude and longitude at BODC.

Bathymetric depth from the GEBCO Centenary 1-Minute Global Grid was merged into the file as a supplementary source of bathymetry for comparison purposes.

Project Information

Rapid Climate Change (RAPID) Programme

Rapid Climate Change (RAPID) is a £20 million, six-year (2001-2007) programme of the Natural Environment Research Council (NERC). The programme aims to improve our ability to quantify the probability and magnitude of future rapid change in climate, with a main (but not exclusive) focus on the role of the Atlantic Ocean's Thermohaline Circulation.

Scientific Objectives


Overall 38 projects have been funded by the RAPID programme. These include 4 which focus on Monitoring the Meridional Overturning Circulation (MOC), and 5 international projects jointly funded by the Netherlands Organisation for Scientific Research, the Research Council of Norway and NERC.

The RAPID effort to design a system to continuously monitor the strength and structure of the North Atlantic Meridional Overturning Circulation is being matched by comparative funding from the US National Science Foundation (NSF) for collaborative projects reviewed jointly with the NERC proposals. Three projects were funded by NSF.

A proportion of RAPID funding as been made available for Small and Medium Sized Enterprises (SMEs) as part of NERC's Small Business Research Initiative (SBRI). The SBRI aims to stimulate innovation in the economy by encouraging more high-tech small firms to start up or to develop new research capacities. As a result 4 projects have been funded.

RAPID - Cape Farewell and Eirik Ridge: Interannual to Millennial Thermohaline Circulation Variability

This project was funded under the NERC Rapid Climate Change Programme, grant number NER/T/S/2002/00453. Dr. Sheldon Bacon (Southampton Oceanography Centre) was the Principal Investigator, with co-Investigators from the University of Southampton, Prof. D. A. Stow and Dr. E. J. Rohling. The project started in December 2003 and ended in November 2008.

The project used a combination of hydrography and palaeoceanography measurements to determine the spectrum of variability of the Deep Western Boundary Current, on timescales from days to millennia. The project focused on deglacial to Holocene variability; in particular, seeking to characterise the onset and endings of three cold periods: the Younger Dryas (YD; 12.5-11.5 ka BP), the ~8.2 ka event, and the Little Ice Age (LIA; 16th-19th century AD).

The objectives of the project included:

Most of the fieldwork was carried out on 2 cruises in the Cape Farewell and Irminger Sea vicinity:

Cruise Start End Comments
D298 2008-08-23 2005-09-05 Work included mooring deployments, sediment coring, sampling for isotopes and CTD casts
D309-310 2006-08-18 2006-09-05 Work included mooring turn-arounds and CTD casts.

Data Activity or Cruise Information


Cruise Name D298
Departure Date 2005-08-23
Arrival Date 2005-09-25
Principal Scientist(s)Sheldon Bacon (National Oceanography Centre, Southampton)
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
Q value below limit of quantification