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Metadata Report for BODC Series Reference Number 808729


Metadata Summary

Data Description

Data Category Bathymetry
Instrument Type
NameCategories
Global Positioning Satellite System  NAVSTAR Global Positioning System receivers
Simrad EA500 echosounder  single-beam echosounders
Instrument Mounting research vessel
Originating Country United Kingdom
Originator Dr Stuart Cunningham
Originating Organization Southampton Oceanography Centre (now 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 D279_PRODQXF_NAV
BODC Series Reference 808729
 

Time Co-ordinates(UT)

Start Time (yyyy-mm-dd hh:mm) 2004-04-04 16:43
End Time (yyyy-mm-dd hh:mm) 2004-05-08 23:59
Nominal Cycle Interval 120.0 seconds
 

Spatial Co-ordinates

Start Latitude 26.49330 N ( 26° 29.6' N )
End Latitude 27.28080 N ( 27° 16.8' N )
Start Longitude 78.91810 W ( 78° 55.1' W )
End Longitude 15.42170 W ( 15° 25.3' 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 -
 

Parameters

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
APSAGP011Metres per secondSpeed of measurement platform relative to ground surface {speed over ground} 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
PTCHGP011DegreesOrientation (pitch) of measurement device by unspecified GPS system
ROLLGP011DegreesOrientation (roll angle) of measurement device by unspecified GPS system

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.

Specifications

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.

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.

RAPID Cruise D279 Underway Navigation and Bathymetry Instrumentation

There are four GPS receivers on RRS Discovery; the Trimble 4000 differential GPS which is a differential GPS, the Glonas GPS which uses a combination of Russian and American satellite networks, the Ashtech GPS and GPS 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 D279 Underway Meteorology, Surface Hydrography and Navigation Series

Cruise details

Dates 4 April 2004 - 10 May 2004
Principal Scientific Officer Dr Stuart Cunningham (SOC)
Cruise Report Cunningham, S. A., 2005. RRS Discovery Cruise D279 04 APR - 10 MAY 2004. A Transatlantic hydrography section at 24.5°N. Southampton, UK, National Oceanoraphy Centre Southampton.(National Oceanography Centre Southampton Cruise Report No. 54).

D279 travelled from Freeport in the Bahamas across the Atlantic to Tenerife in Spain. After initially focussing on the collection of chemical data from the Florida Current at 27°N, the main focus of the cruise was the collection of hydrographic data across the Atlantic Ocean between approximately 24 and 27.5°N.

It should be noted that the data series supplied by the originator covers 04 April to 08 May 2004, which is less that the duration of the cruise.

Data Processing Procedures

Two minute averaged sea surface hydrographic and meteorological data, together with navigation and bathymetric files, were transferred from PSTAR format into BODC internal format (QXF), using time (UTC) as the primary linking key, to allow use of the in-house visualisation tool (EDSERPLO). Reformatting and data calibration was carried out, and is discussed in the individual instrument sections. Each data channel was visually inspected and any spikes or periods of dubious data flagged as suspect. The capabilities of the workstation screening software allows comparative screening checks between channels.

The qxf file then underwent a further step. This involved using Matlab to split the qxf file into three separate qxf files. One contained data for hydrography, one for meterological data and the final qxf file held the navigation data.

RAPID Cruise D279 Underway Navigation and Bathymetry Processing

Originator's processing

Data from all four navigation strams along with the ship's gyrocompass readings were logged to the RVS system. A standard PSTAR best navigation file was updated regularly from the bestnav data stream. The preferred input for bestnav is the Trimble 4000 as it has been found to be more accurate on previous cruises. If there were gaps in the Trimble 4000 data, the bestnav process used other inputs as necessary in the order Glonass, Ashtech, G12, gyro.

The PES fish transducer was deployed shortly after leaving Freeport and was used in preference to the hull transducer for the duration of the cruise. The Simrad Echosounder was used continously throughout the cruise for bottom detection.

BODC Processing

Latitude and Longitude

A program was run which locates any gap in the latitude and longitude channels and checks to ensure that the ship's speed does not exceed 15 knots. No excessive ship speeds were found. There are several short gaps in latitude and longitude, which were filled with linear interpolation using the BODC program navint. Distance run was recomputed to create a continuous record.

Ship's velocity

Ship's east-west and north-south velocities were converted from ms-1 to cm-1 at BODC

Bathymetry

Bathymetry data were corrected for variations in speed of sound using Carter's tables during on-board processing.


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

  • To establish a pre-operational prototype system to continuously observe the strength and structure of the Atlantic Meridional Overturning Circulation (MOC).
  • To support long-term direct observations of water, heat, salt, and ice transports at critical locations in the northern North Atlantic, to quantify the atmospheric and other (e.g. river run-off, ice sheet discharge) forcing of these transports, and to perform process studies of ocean mixing at northern high latitudes.
  • To construct well-calibrated and time-resolved palaeo data records of past climate change, including error estimates, with a particular emphasis on the quantification of the timing and magnitude of rapid change at annual to centennial time-scales.
  • To develop and use high-resolution physical models to synthesise observational data.
  • To apply a hierarchy of modelling approaches to understand the processes that connect changes in ocean convection and its atmospheric forcing to the large-scale transports relevant to the modulation of climate.
  • To understand, using model experimentation and data (palaeo and present day), the atmosphere's response to large changes in Atlantic northward heat transport, in particular changes in storm tracks, storm frequency, storm strengths, and energy and moisture transports.
  • To use both instrumental and palaeo data for the quantitative testing of models' abilities to reproduce climate variability and rapid changes on annual to centennial time-scales. To explore the extent to which these data can provide direct information about the thermohaline circulation (THC) and other possible rapid changes in the climate system and their impact.
  • To quantify the probability and magnitude of potential future rapid climate change, and the uncertainties in these estimates.

Projects

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.


Data Activity or Cruise Information

Cruise

Cruise Name D279
Departure Date 2004-04-04
Arrival Date 2004-05-10
Principal Scientist(s)Stuart A Cunningham (Southampton Oceanography Centre)
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