Metadata Report for BODC Series Reference Number 1029655
Metadata Summary
Problem Reports
Data Access Policy
Narrative Documents
Project Information
Data Activity or Cruise Information
Fixed Station Information
BODC Quality Flags
SeaDataNet Quality Flags
Metadata Summary
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Time Co-ordinates(UT) |
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Parameters |
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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 Maritime AS EM 1002 and EM 1002S multibeam echosounders
The EM 1002 is a multibeam echosounder designed for seabed mapping in water depths of up to 1000 m. The transducer array operates at a frequency of 95 kHz, and includes 111 individual beams with a 2° beam width. The across-track coverage is approximately 1500 m in deep water and up to 7.4 times the depth beneath the transducer in shallow water. Normal angular coverage is adjustable up to 150° but can be increased to 5° above the horizontal on one or both sides of the transducer when surveying from the bottom to the surface along shorelines, river banks and man-made structures.
The standard EM 1002 system has three different pulse lengths to maximize coverage in deep water. A shallow-water version, the EM 1002S, is also available. The EM 1002S is identical to the EM 1002, other than being equipped with only the shortest of the three pulse lengths. The EM 1002S may be used at depths over 600 m, but across-track coverage is limited to approximately 1000 m, and is typically less than half that of a standard EM 1002 for depths greater than 300 m.
The EM 1002 and EM 1002S come with electronic roll stabilisation and the option of mechanical pitch compensation.
Specifications
| Transducer frequency | 95 kHz |
| Maximum ping rate | > 10 Hz |
| Number of beams per ping | 111 |
| Beamwidth | 2° |
| Beam spacing | Equidistant and equiangle |
| Coverage sector | up to 150° (usable up to 190°) |
| Depth range from transducers | 2 to 1000 m |
| Depth resolution | 2, 4 or 8 cm |
| Pulse lengths | 0.2*, 0.7 and 2 ms |
| Range sampling rate | 9 kHz (8 cm) |
| Beamforming method | phase interpolated |
*This pulse length used by the EM 1002S.
Further details can be found in the manufacturer's specification sheet.
BODC Data Processing
A total of 14 .grd files were provided to BODC in NetCDF format. In addition to these files, BODC were also provided with the raw xyz files, which are available upon request. The files were transferred using BODC generated Matlab code into BODC standard NetCDF format.
During transfer the original variables are mapped to unique BODC parameter codes. The parameter mapping can be seen below.
| Originator's variable | Units | Description | BODC Parameter Code | Units | Comments |
|---|---|---|---|---|---|
| x | Degrees | Longitude | ALONZZ01 | Degrees | Eastern values are positive |
| y | Degrees | Latitude | ALATZZ01 | Degrees | Northern values are positive |
| z | Metres | Sea floor depth | BATHHGHT | Metres | Converted to an elevation by mutliplying by -1 |
Due to the nature of the files, screening via in-house visualisation software was not possible. Instead, during transfer plots of the original files and of the transferred files are produced. These can then be visually compared to check that the data has transferred correctly.
Originator's Data Processing
The MV Franklin 0206 cruise took place between the 3rd August 2006 and the 23rd August 2006, around the Northern coast of Scotland. Bathymetry data were collected by a Simrad EM1002 multi-beam echo sounder.
Project Information
No Project Information held for the Series
Data Activity or Cruise Information
Cruise
| Cruise Name | 02/06 |
| Departure Date | 2006-08-03 |
| Arrival Date | 2006-08-23 |
| Principal Scientist(s) | Colin L Jacobs (National Oceanography Centre, Southampton) |
| Ship | MV Franklin |
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 |
| B | nominal value |
| Q | value below limit of quantification |
