Choose time units in output netcdf

Is there any way to define the units in output netcdf created from to_netcdf method without having to manually convert the time objects into floats for example? It could maybe be handy if the units attribute of time coordinate could be modified and the modified value (if CF-compliant) used for encoding time in the output netcdf. Currently, to_netcdf raises ValueError: Failed hard to prevent overwriting key 'units' if the attribute is modified.

Thanks

[rvalenzuelar]

Hello,

I’m having similar issues. However, I’m creating a dataset from a dict (data are packed in Matlab file).

The dataset is ds_ivt and I have tried:

ds_ivt.time.encode['units'] = 'days since 1900-01-01'

and

ds_ivt.to_netcdf('ds_ivt.nc',encoding={'time':{'units':'days since 1900-01-01'}})

The .info() method retrieves:

ds_ivt.info()
xarray.Dataset {
dimensions:
	lat = 161 ;
	lon = 291 ;
	time = 1460 ;
variables:
	float32 lat(lat) ;
		lat:units = degrees ;
	float32 lon(lon) ;
		lon:units = degrees ;
	datetime64[ns] time(time) ;
		time:units = days since 1900-01-01 ;
	float32 iqu(time, lat, lon) ;
		iqu:units = kg m-1 s-1 ;
	float32 iqv(time, lat, lon) ;
		iqv:units = kg m-1 s-1 ;
// global attributes:
}

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