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For featureType "point" all points in the file are imported together to form a single track. An example input NetCDF structure for this can be found in the CF conventions document Appendix H section H.1. Point Data.

For featureType "trajectory" this parser supports two different input formats, the simplest format provides only a single track per file, i.e. variables in the NetCDF file must be one dimensional and only have a time dimension. For an example of the format that can be imported with this import type, see http://cfconventions.org/cf-conventions/cf-conventions.html#_single_trajectory, see the CF conventions document Appendix H, section H.4.2. Single trajectory.

In Delft FEWS version 2020.02 an additional format has been implemented, as described in the CF conventions document Appendix H, section H.4.1. Multidimensional array representation of trajectories. This format supports multiple trajectories in one file, especially suited for datasets where all trajectories have the same time dimension and are available for the same period. 

Track x,y coordinates are imported as normal timeSeriestimeseries, i.e. they do not get any special treatment in this parser and are handled like other data variables. In fact this parser does not know about tracks at all. Tracks are constructed in other places in Delft-FEWS (e.g. trackLayer in GridDisplay) where it is possible to combine a data timeSeries timeseries with two timeSeries timeseries with x and y coordinates in the configuration to create a track.

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Consequences for coordinates

The values of coordinate timeSeries timeseries are imported as normal timeSeriestimeseries. Therefore for the coordinate timeSeries timeseries there must be timeSeriesSets configured in the import run and parameters configured in the id map. Furthermore the imported coordinates are rounded to floats. For global lat,lon coordinates in degrees this corresponds to a spatial accuracy of about 4 meters.

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Note that in the idMapping, the external parameterIds parameter Ids must match the variable names used in the NetCDF file exactly (case sensitive). The external locationIds location Ids are not used by this import only in case the format providing multiple trajectories per file is used (Delft FEWS 2020.02 and later).

Example import id map config file:

<?xml version="1.0" encoding="UTF-8"?>
<idMap xmlns="http://www.wldelft.nl/fews" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.wldelft.nl/fews http://fews.wldelft.nl/schemas/version1.0/idMap.xsd" version="1.1">
    <parameter internal="latitude" external="lat"/>
    <parameter internal="longitude" external="lon"/>
    <parameter internal="H.m" external="ssha"/>
    <!-- dummy locationId (not used by when importing a single track importformat) -->
    <location internal="H-2001" external="dummy"/>
</idMap>

Example time series import run config file:

From 2021.01 it is possible to import NETCDF attributes as timeSeriesProperties into FEWS. This can be configured in the properties (see example below). Using the example config, the value of the NETCDF attribute ‘systemid’ will be imported as a timeSeriesProperty ‘rivieren2’.

Since 2021.02 it is also possible to export timeSeriesProperties as NETCDF attributes. You can find a config example here:  https://publicwiki.deltares.nl/display/FEWSDOC/NETCDF-CF_GRID+Export

<?xml version="1.0" encoding="UTF-8"?>
<timeSeriesImportRun xmlns="http://www.wldelft.nl/fews" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.wldelft.nl/fews http://fews.wldelft.nl/schemas/version1.0/timeSeriesImportRun.xsd">
    <import>
        <general>
            <importType>NETCDF-CF_TRAJECTORY</importType>
            <folder>../junit_test_output/nl/wldelft/fews/system/plugin/dataImport/TimeSeriesImportTestData/import/netcdf_track</folder>
            <idMapId>netcdf_track</idMapId>
        </general>
		<properties>
			<string key="netcdfattribute:taskrunid" value='timeseriesproperty:rivieren1'/>
			<string key="netcdfattribute:systemid"    value='timeseriesproperty:rivieren2'/>
		</properties>
	    <timeSeriesSet>
            <moduleInstanceId>NetcdfTrackImportTest</moduleInstanceId>
            <valueType>scalar</valueType>
            <parameterId>latitude</parameterId>
            <locationId>H-2001</locationId>
            <timeSeriesType>external historical</timeSeriesType>
            <timeStep unit="nonequidistant"/>
            <readWriteMode>add originals</readWriteMode>
        </timeSeriesSet>
        <timeSeriesSet>
            <moduleInstanceId>NetcdfTrackImportTest</moduleInstanceId>
            <valueType>scalar</valueType>
            <parameterId>longitude</parameterId>
            <locationId>H-2001</locationId>
            <timeSeriesType>external historical</timeSeriesType>
            <timeStep unit="nonequidistant"/>
            <readWriteMode>add originals</readWriteMode>
        </timeSeriesSet>
        <timeSeriesSet>
            <moduleInstanceId>NetcdfTrackImportTest</moduleInstanceId>
            <valueType>scalar</valueType>
            <parameterId>H.m</parameterId>
            <locationId>H-2001</locationId>
            <timeSeriesType>external historical</timeSeriesType>
            <timeStep unit="nonequidistant"/>
            <readWriteMode>add originals</readWriteMode>
        </timeSeriesSet>
    </import>
</timeSeriesImportRun>

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