Cannot save to netcdf where dataset contains a structured numpy array

[qAp]

I have this netcdf file which I can load into a xarray.Dataset containing a single data variable. This data variable consists of a structured numpy array. Loading it with:

import xarray as xr
import pandas as pd
import numpy as np

ds = xr.open_dataset('puftrac_2018103100ChinShan_Cs.nc')

returns

<xarray.Dataset>
Dimensions:  (serial: 2657664)
Dimensions without coordinates: serial
Data variables:
    trajec   (serial) {'names':['ReleaseTime','CurrentTime','Longitude','Latitude','RelativeHeight','SigX','SigY','SigZ','AirConcentrationR','GroundConcentrationR'], 'formats':['<i8','<i8','<f4','<f4','<f4','<f4','<f4','<f4','<f4','<f4'], 'offsets':[0,8,16,20,24,28,32,36,40,44], 'itemsize':48, 'aligned':True} ...
Attributes:
    Start Time:      1540944000
    End Time:        1541635200
    Release Period:  300
    Dump Period:     300

I can't save it back to netcdf with

ds.to_netcdf('tmp.nc')

getting

~/anaconda3/lib/python3.6/site-packages/xarray/backends/netCDF4_.py in _get_datatype(var, nc_format, raise_on_invalid_encoding)
    105 def _get_datatype(var, nc_format='NETCDF4', raise_on_invalid_encoding=False):
    106     if nc_format == 'NETCDF4':
--> 107         datatype = _nc4_dtype(var)
    108     else:
    109         if 'dtype' in var.encoding:

~/anaconda3/lib/python3.6/site-packages/xarray/backends/netCDF4_.py in _nc4_dtype(var)
    128     else:
    129         raise ValueError('unsupported dtype for netCDF4 variable: {}'
--> 130                          .format(var.dtype))
    131     return dtype
    132 

ValueError: unsupported dtype for netCDF4 variable: {'names':['ReleaseTime','CurrentTime','Longitude','Latitude','RelativeHeight','SigX','SigY','SigZ','AirConcentrationR','GroundConcentrationR'], 'formats':['<i8','<i8','<f4','<f4','<f4','<f4','<f4','<f4','<f4','<f4'], 'offsets':[0,8,16,20,24,28,32,36,40,44], 'itemsize':48, 'aligned':True}

Any thing I could do here? (I actually intend to change some values before writing back to disk.) The netcdf file can be found here: https://drive.google.com/open?id=1H5M3N_lv471JyOalcA3Bw_Y2ed0EX6xt

[shoyer]

We don't currently support this in xarray but would be welcome this feature. See #1626 for existing discussion.