Exporting single beam Sv, TS, angular position data to the ICES SONAR-netCDF4 Format (*.nc)

Echoview supports the export of single beam Sv, TS and/or angular position variable data and supported time series data to the ICES SONAR-netCDF4 file format using Type 5 equations. Where a position and/or a heading variable are used by the platform, GPS and heading data will also be written to the file format. Heave, pitch and roll are not currently supported.

The output *.nc file may be added to a fileset.

Export via Echogram menu

Exports a single variable type from single beam Sv, TS or angular position data.

1. Open an echogram of a supported variable type.
2. On the Echogram menu, select Export, To ICES netCDF4 Format ...
3. On the Export to ICES netCDF4 Format dialog box enter a file name.
4. Click Save.

Measurement - ICES SONAR-netCDF4 exporter

Exports a single variable or multiple supported variables, where multiple variables are supported operands of the Measurement - ICES SONAR-netCDF4 exporter.

1. On the Dataflow Toolbox, select the Measurement - ICES SONAR-netCDF4 exporter, then drag and drop it onto the Dataflow window.
2. On the Dataflow window, select the Measurement - ICES SONAR-netCDF4 exporter object, right-click it, and on the Shortcut menu select Exporter Properties.
3. On the Operands tab, specify a single supported operand or multiple supported operands.
4. On the Measurement - ICES SONAR-netCDF4 tab, specify the range of pings for export.
5. Click OK.
6. Double-click the Measurement - ICES SONAR-netCDF4 exporter object.
7. On the Export to ICES netCDF4 Format dialog box, enter a file name.
8. Click Save.

Notes:

• On the Export Progress dialog box, you can use the Cancel export button. This will stop the export and delete the last partial *.nc file.
• When the export or exporter does not output a file, a diagnostic message may have been sent to the Messages dialog box. See also the Support details.
• For pulse compressed variables, Echoview exports values only; the complex value is not exported.
• Echoview reports whether the export completed successfully or stopped before completion.
• When calibration changes after the nth ping, the export won't include the nth ping, ie., if calibration changes partway through the data, pings after the change may not be included in the export.

ICES SONAR-netCDF4 Format *.nc

Echoview exports single beam ping data such that it conforms to the ICES SONAR-netCDF4 (version 2) document. Echoview writes the values of a selected variable, or multiple variables, for Sv and/or TS and/or angular position data types to the output file.

Echoview uses the Type 5 conversion, which the SONAR-netCDF4 convention document notes "is intended for sonars for which the manufacturer computes standard TS and Sv values as defined in MacLennan et al. (2002)." Where a derived angular position variable is available, Echoview uses the methods described in Chapter 6. Split-aperture beams and subsection 6.1 Angles stored in file to output angular position values to the *.nc file.

The ICES SONAR-netCDF4 convention specifies data obligations for elements of the file format and describes how missing data are handled. Data obligation options include:

• Mandatory
• Mandatory if applicable or available
• Recommended
• Optional

Where an element is 'Mandatory' and a value is available, the value is output to the *.nc file.

Where an element is 'Mandatory', or the element is 'Mandatory if applicable or available' and it is applicable, and the value is unavailable, a default Echoview calibration value is output for the element.

For elements that are 'Optional', 'Recommended', or 'Mandatory if applicable or available' and it is not applicable, Echoview outputs an element value of '+NaN'.

Notes:

• Refer to the Support details for additional information.
• See also COM Scripting: EvVariableAcoustic.ExportICESSONARNetCDF4 and EvVariableVirtual.ExportICESSONARNetCDF4 support exporting a single single-beam variable.
• EvFile.Exporters, EvExporter.Export, EvExporter.ExportType, and enum eTypeIcesNetcdf = 19 support a pre-configured Measurements - ICES SONAR-netCDF4 exporter that allows multiple single beam operands on the Dataflow window.
• The output file format contains prescribed calibration settings. Values for these settings are supplied by the calibration settings of the requested variable. Calibration values may be read from the variable's source data file, or use default values or ECS values.

See also

Exporting in Echoview
About exporting data
Export file formats
About exporting measurement data