nexrad as netcdf

[Gilad R]

I use nexrad_level2.py and I didn't find how to retrieve variables from nexRad file like:

scanR_HI = 8;
    gateR_HI = 1832;
    radialR_HI = 720;
    scanR = 6;
    gateR = 1548;

    ..

    ..

if you take a nexrad file and put in panoply program, you will see those variables

any idea if possible to do this ?

Thanks

[Jonathan J. Helmus]

If you have NEXRAD data in NetCDF format it most likely has been
converted for the raw NEXRAD Level II format using the NetCDF-Java
library [1]. Within Py-ART this is considered a CDM NEXRAD Level 2 file
and can be read using pyart.io.read_nexrad_cdm or with the file type
automatically determined using pyart.io.read. If you wanted to read
data from this file outside of Py-ART using Python I would suggest using
the netcdf4-python library [2]. The nexrad_cdm.py module [3] may
provide helpful details on how Py-ART implements this read.

Cheers,

- Jonathan Helmus


[1]
http://www.unidata.ucar.edu/software/thredds/current/netcdf-java/documentation.htm
[2] https://github.com/Unidata/netcdf4-python
[3] https://github.com/ARM-DOE/pyart/blob/master/pyart/io/nexrad_cdm.py

[Gilad R]

Thanks for the detailed answer.

I tried both options (nexrad_cdm and netcdf4-python), and when I try something like

dataset = netCDF4.Dataset('KGWX_20150629_0924')

I get error

RuntimeError: NetCDF: Unknown file format

The file is a regular file from

http://mesonet-nexrad.agron.iastate.edu/level2/raw/KGWX/

I guess I need only the attributes, but no idea how to access it

Thanks again :)

[Gilad R]

another question.. I try to figure out when nexRad file is ready, as it firsts uploads with 2 levels, then with 4 levels etc on the website. How can I tell that I reached maximum scans/levels/cuts/sweeps

in the file ? any idea ?

I tried to look on num_cuts in nexrad_level2.py, but it gives me sometimes wrong number 19, when it is 14 (reflectivity_h = 8 + reflectivity = 6)

Thanks :)

[Jonathan Helmus]

The files hosted at the iastate.edu site are raw NEXRAD Level II files not NetCDF files which can be read using Py-ART with the statement

pyart.io.read('KGWX_20150703_0815')

or

radar = pyart.io.read_nexrad_archive('KGWX_20150703_0815')

Cheers,

    - Jonathan Helmus

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