Unexpected output with wradlib.vis.plot_scan_strategy

Python
1

Hye Dear All,
I am trying to use the plot scan strategy, below is my code.

file = 'CFRADIAL/RSCHR_01APR2022_003424_L2B_STD.nc'
vol = xradar.io.backends.cfradial1.open_cfradial1_datatree(file)
nrays = 360
nbins = 1600
range_res = 150
ranges = np.arange(nbins) * range_res
elevs = vol.root.sweep_fixed_angle.values
sitecoords = (
    vol.root.longitude.values.item(),
    vol.root.latitude.values.item(),
    vol.root.altitude.values.item(),
)

beamwidth = 1.0 
ax = wrl.vis.plot_scan_strategy(ranges, elevs, sitecoords)

but the plot I am getting I am sure it is wrong, see belong, the rays are not continuous, I tried everything, but unable to resolve the issue, please help in this regard.

image
image999×466 119 KB

below is the link for my file,

2

Welcome to openradar discourse @nitigsingh,

I’ve moved your post to a new topic and made the code a bit more accessible.

There are several problems with your source file.

It doesn’t contain a valid time unit, only seconds since yyyy-mm-ddThh:mm:ssZ, where some valid timestring should be provided. I’ve had to use decode_times=False in the call to open_cfradial1_datatree to read the file.

Another issue is with time_coverage_start and time_coverage_end variables. They should be just two time-strings but are extending across the time-dimension.

A huge problem is that sweep_start_ray_index and sweep_stop_ray_index contain same values for each sweep (80 for the first and 150 for the latter), so correct sweep selection isn’t possible.

There is another issue with the standard_name of VEL where there is an unwanted space inside.

This works for me:

file = 'RSCHR_01APR2022_003424_L2B_STD.nc'
# need to skip time decoding, due to wrong units-string
vol = xradar.io.backends.cfradial1.open_cfradial1_datatree(file, decode_times=False)
nrays = 360
nbins = 1600
range_res = 150
ranges = np.arange(nbins) * range_res
elevs = vol.root.sweep_fixed_angle.values
sitecoords = (
    vol.root.longitude.values.item(),
    vol.root.latitude.values.item(),
    vol.root.altitude.values.item(),
)

beamwidth = 1.0 
ax = wrl.vis.plot_scan_strategy(ranges, elevs, sitecoords)

scan_strategy_isro
scan_strategy_isro1483×699 164 KB

I did not test if Py-ART can somehow workaround these problems.

3

Dear Sir,
thank you so much @kmuehlbauer, i understand the issue:
you are absolutely right that these two are really two big issues,

1.) Another issue is with time_coverage_start and time_coverage_end variables. They should be just two time-strings but are extending across the time-dimension.

2.) A huge problem is that sweep_start_ray_index and sweep_stop_ray_index contain same values for each sweep (80 for the first and 150 for the latter), so correct sweep selection isn’t possible.

but I still do not understand and grasp it to sort it out, so can u give me example with real instances of a proper data in time_coverage_start and time_coverage_end and also values for sweep_start_ray_index and sweep_stop_ray_index , so that I can write function to sort these issue in the radar files…

and another things is when I use decode_times=False in the call to open_cfradial1_datatree to read the file. it did not make any difference on the plot still I see discontinuous rays, I thought I have problem in wradlib or xradar so I updated the library…but no change…even i did not take fix angle and lat long and alt from radar object parameters only using one command library command

ax = wrl.vis.plot_scan_strategy(ranges, elevs, sitecoords)

still the plot is not ehat i expect.
what can be the problem. what am i doing wrong.

can you help me with this
regards
nitig