Missing attribute

[zxdawn]

  File "/student/zhangxin/papers/Arctic/S5P_LNOx/main/s5p_lno2_utils.py", line 377, in save_data
    'time_coverage_start': scn['nitrogendioxide_tropospheric_column'].attrs['time_coverage_start'],

[zxdawn]

This is related to satpy tropomi reader. I have created a PR for this.

[zxdawn]

To save the attribute to a group,

S5P-LNO2/main/s5p_lno2_utils.py

Lines 375 to 394 in b570e74

	# set group attributes
	group_attrs = {'s5p_filename': scn.attrs['s5p_filename'],
	'time_coverage_start': scn['nitrogendioxide_tropospheric_column'].attrs['time_coverage_start'],
	'time_coverage_end': scn['nitrogendioxide_tropospheric_column'].attrs['time_coverage_end'],
	'description': 'Subset of official TROPOMI L2 data'
	}
	# set compression
	comp = dict(zlib=True, complevel=7)
	logging.debug(' '*8 + 'Saving S5P products ...')
	scn.save_datasets(filename=output_file,
	datasets=s5p_vnames,
	groups={'S5P': s5p_vnames},
	compute=True,
	group_attrs=group_attrs,
	writer='cf',
	engine='netcdf4',
	compression=comp,
	)

I have to finish another PR of satpy:

pytroll/satpy#1914