support temporal metadata provided by 'time' dimension in NetCDF files

[janzandr]

Requested by @ffilipponi in #552 ...

I additionally suggest to automatically set Date Time reading 'time' dimension in NetCDF file, when available. It would significantly support time series analysis, especially for unevenly spaced time series.

[janzandr]

@ffilipponi, please provide a small NetCDF file for testing.

[ffilipponi]

@janzandr , please find two small samples of time series in NetCDF format:

• unevenly spaced time series
• evenly spaced time series NetCDF_time_series_samples.zip

Please beware that units descriptor string of NetCDF time dimension may contain an origin. Here some examples:

time:units = "seconds since 1970-1-1" time:units = "days since 1970-01-01 00:00:00" time:units = "hours since 1990-11-25 12:00 UTC"

Thanks for considering the new feature request

[janzandr]

Thanks for the datasets. Unfortunately, they don't seem to work in my QGIS:

[ffilipponi]

@janzandr When importing spatially explicit NetCDF datasets in QGIS, you should only select the layers of interest having the chessboard pattern icon (thus excluding mesh and table icons). From the screenshot you provided I can not see what the danger icon refers to. CRS definition within NetCDF file it is sometimes not successfully read by QGIS. It can be set manually later in the layer properties. In general, two QGIS user environment variables to effectively avoid many warnings and issues when importing NetCDF spatial datasets are: IGNORE_XY_AXIS_NAME_CHECKS=YES GDAL_NETCDF_BOTTOMUP=NO

[janzandr]

Strange, I downloaded your files again, and now ist's working :-)