Metadata Report for BODC Series Reference Number 942436

Metadata Summary

Data Description

Data Category Bathymetry
Instrument Type
Global Positioning Satellite System  NAVSTAR Global Positioning System receivers
RD200A echosounder  single-beam echosounders
Instrument Mounting research vessel
Originating Country United Kingdom
Originator Prof Geoff Millward
Originating Organization University of Plymouth Institute of Marine Studies (now University of Plymouth, School of Geography, Earth and Environmental Sciences)
Processing Status banked
Online delivery of data Download available - Ocean Data View (ODV) format
Project(s) LOIS River-Atmosphere-Coast Study (RACS)

Data Identifiers

Originator's Identifier CH108C_NAV
BODC Series Reference 942436

Time Co-ordinates(UT)

Start Time (yyyy-mm-dd hh:mm) 1993-12-11 15:41
End Time (yyyy-mm-dd hh:mm) 1993-12-22 10:20
Nominal Cycle Interval 30.0 seconds

Spatial Co-ordinates

Start Latitude 53.73780 N ( 53° 44.3' N )
End Latitude 51.35290 N ( 51° 21.2' N )
Start Longitude 0.28770 W ( 0° 17.3' W )
End Longitude 3.38840 W ( 3° 23.3' W )
Positional Uncertainty 0.05 to 0.1 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 (WGS84) by unspecified GPS system
ALONGP011DegreesLongitude east (WGS84) by unspecified GPS system
MBANUA011MetresSea-floor depth (below instantaneous sea level) {bathymetric depth} in the water body by echo sounder (SV=1500m/s)

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 data exist between 17:41 on 17/12/93 and 18:22 on 18/12/93 while the ship was docked in Grimsby for repair.

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

Global Positioning Satellite System

A location system of unspecified make or model that determines location on the Earth's surface using the Global Positioning Satellite Network. Angular co-ordinates are given relative to WGS84 CRS. Other parameters such as platform velocity may be derived from this.

CH108_c Sea surface navigation instrument details

Navigation was conducted using a Global Positioning System and ship-mounted single-beam echo sounder. Instrument details are given in the table below.

Instrument type Make and model Serial Number Manufacturer's details available?
GPS unspecified - -
Echo sounder RD200A - No

CH108_c Underway Navigation Series

Navigation Processing Notes

Positional Data

GPS was the primary navigation system used on this cruise. When no GPS fixes were available, the ship's position was determined by dead reckoning based upon the ship's gyro and EM log. Once a fix was obtained after a period of dead reckoning, the surface drift velocity was computed. If this exceeded 4 knots the data were automatically flagged suspect. The positional error due to surface drift was then retrospectively applied over the period of dead reckoning.

At BODC a program 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. The bridge logs were used to manually enter as many positions as possible during periods when navigation wasn't automatically logged. These cover critical points such as course alterations and arrival/departure at stations. Any remaining null values were filled by linear interpolation. The maximum gap interpolated for this cruise was 23 hours 19 minutes, commencing at 18:44 on 17/12/93, while the ship was docked in Grimsby for repairs.


Bathymetric depth was logged by the ABC system from an RD200A echo sounder, which recorded the depth of water under the keel (i.e. depth less 4 metres). Before screening, this channel was converted to bathymetric depth by the addition of 4 metres to all non-null values.

CH108_c Sea surface Hydrography, Meteorology and Navigation Series


Seawater was continuously pumped from the hull of the ship at a depth of approximately 4 m from the ship's non-toxic supply. The thermosalinograph was fed through a small (100-litre) header tank. A large plastic tank on the starboard deck was fed directly from the non-toxic manifold and contained the transmissometer and fluorometer. Baffles in the tank ensured that a continuous flow was maintained over the instruments. The nutrient autoanalyser was fed from plastic tubing connected to taps on the non-toxic supply.

The Endeco dissolved oxygen system electrodes were placed in a Perspex cell (approx. 1 litre volume) supplied from the general non-toxic supply via a constant head device at 2 litres/minute.

Calibration samples were either taken from the non-toxic tap in the wet laboratory or the thermosalinograph outlet.

A separate clean system was fitted to supply seawater to the trace metal analysis system. A specially adapted PES fish was deployed on the port side just aft of the bow at a depth of between 1m and 3m. A plastic hose led from this directly to the analytical equipment. Water was driven through the system by a large perisaltic pump.

Data Acquisition

For most parameters, data logging and initial processing were handled by the RVS ABC system. The Level A sampling microcomputer digitised an input voltage, applied a time stamp and transferred the data via the Level B disk buffer onto the Level C where the data records were assembled into files. The only exceptions were the oxygen data from the Endeco system and the trace metal analysers, which were logged by PCs. Care was taken to ensure that the PC clocks were synchronised with the master clock used for the Level A time stamps.

Sampling rates varied from 10 seconds to several minutes.

The Level C included a suite of calibration software, which was used to apply initial calibrations to convert raw counts into engineering units. At the end of the cruise the Level C disk base was transferred to BODC for further processing.

BODC Data Processing Procedures

Data from the underway files were merged into a common file (the binary merge file) using time as the primary linking key with a sampling interval of 30 seconds. Data sampled at higher frequencies were reduced by averaging. Data logged as voltages (e.g.PAR, nutrients) were converted to engineering units.

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 undertake all possible comparative screening checks between channels.

Project Information

LOIS River-Atmosphere-Coast Study (LOIS - RACS)


The Land-Ocean Interaction Study (LOIS) was a NERC research programme designed to study processes in the coastal zone. The Rivers, Atmosphere and Coasts Study (RACS) was a major component of LOIS that looked at land-sea interactions in the coastal zone and the major exchanges (physical, chemical and biological) between rivers and estuaries and the atmosphere. The study focused on the east coast of the UK from the Wash to the Tweed.

RACS included several sub-components

RACS (A) was coordinated by the University of East Anglia and RACS (C) by the Plymouth Marine Laboratory.


The bulk of the RACS (A) data set was collected during two field campaigns in the winter (October/November) of 1994 and the summer (May/June) of 1995. During these campaigns data were collected continuously from the University of East Anglia Atmospheric Observatory at Weybourne on the north Norfolk coast. An instrumented vessel was stationed offshore to provide a second sampling site to allow changes in a given air mass to be monitored. The Imperial College Jetstream research aircraft made one flight during each campaign to provide a link between the two surface stations. The Jetstream made four additional flights in 1996 and 1997.


The coastal oceanographic survey

The coastal oceanographic data set was collected during a series of 17 RRS Challenger cruise legs. Most cruises covered two survey grids. One from Great Yarmouth to the Humber designed around the distribution of the sandbanks and a second simple zig-zag grid from the Humber to Berwick on Tweed. A large number of anchor stations, usually over one or two tidal cycles, were worked in the area of the Humber mouth or the Holderness coast.

The Humber estuarine study

The Humber estuarine data set was collected during a series of 33 campaigns on the Environment Agency vessels Sea Vigil and Water Guardian in the Humber, Trent and Ouse river systems at approximately monthly intervals between June 1993 and December 1996. Each campaign consisted of two or three one-day cruises. The tracks covered the estuary from the tidal limits of both Trent and Ouse to Spurn Point. Instrumental and sample data are available from a series of fixed stations that were sampled during every campaign.

The Tweed estuarine study

The Tweed estuarine data set was collected during a series of 13 campaigns using RV Tamaris in association with a rigid inflatable vessel at approximately monthly intervals between July 1996 and July 1997. Each campaign covered the tidal reaches of the River Tweed.

The Holderness experiment

The Holderness Experiment was designed to monitor the process of sediment transport along the Holderness coastline. It consisted of three moored instrument deployments during the winters of 1993-1994, 1994-1995 and 1995-1996. Mooring platforms were deployed at eight stations along two lines off the Holderness coast. A northerly and a southerly line of four stations each were used (N1 - N4 and S1 to S4) with the lowest numbers being inshore. Both lines were approximately perpendicular to the coast, although the S4 station lay to the south of the S line, off Spurn Head.

Data Activity or Cruise Information


Cruise Name CH108C
Departure Date 1993-12-11
Arrival Date 1993-12-23
Principal Scientist(s)Geoff Millward (University of Plymouth Institute of Marine Studies)
Ship RRS Challenger

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