.. _sphx_glr_examples_formats_NEXRAD_Level_2_File.py:


NEXRAD Level 2 File
===================

Use MetPy to read information from a NEXRAD Level 2 (volume) file and plot



.. code-block:: python

    import matplotlib.pyplot as plt
    import numpy as np

    from metpy.cbook import get_test_data
    from metpy.io import Level2File
    from metpy.plots import add_metpy_logo, ctables








.. code-block:: python


    # Open the file
    name = get_test_data('KTLX20130520_201643_V06.gz', as_file_obj=False)
    f = Level2File(name)

    print(f.sweeps[0][0])





.. rst-class:: sphx-glr-script-out

 Out::

    (Msg31DataHdr(stid=b'KTLX', time_ms=73003850, date=15846, az_num=1, az_angle=123.20343017578125, compression=0, rad_length=6856, az_spacing=1, rad_status=5, el_num=1, sector_num=1, el_angle=0.5987548828125, spot_blanking=None, az_index_mode=0.25, num_data_blks=7, vol_const_ptr=68, el_const_ptr=112, rad_const_ptr=124), VolConsts(type=b'R', name=b'VOL', size=44, major=1, minor=0, lat=35.33305740356445, lon=-97.27748107910156, site_amsl=369, feedhorn_agl=19, calib_dbz=-43.72919845581055, txpower_h=185.05685424804688, txpower_v=181.45559692382812, sys_zdr=-0.08510557562112808, phidp0=25.0, vcp=12, processing_status=None), ElConsts(type=b'R', name=b'ELV', size=12, atmos_atten=-0.012, calib_dbz0=-42.4375), RadConstsV1(type=b'R', name=b'RAD', size=20, unamb_range=466.0, noise_h=-79.71426391601562, noise_v=-79.39848327636719, nyq_vel=8.3), {b'REF': (DataBlockHdr(type=b'D', name=b'REF', reserved=0, num_gates=1832, first_gate=2.125, gate_width=0.25, tover=5.0, snr_thresh=1.6, recombined=None, data_size='B', scale=2.0, offset=66.0), array([  6.5,   2.5,  11. , ...,   nan,   nan,   nan])), b'ZDR': (DataBlockHdr(type=b'D', name=b'ZDR', reserved=0, num_gates=1192, first_gate=2.125, gate_width=0.25, tover=5.0, snr_thresh=1.6, recombined=None, data_size='B', scale=16.0, offset=128.0), array([ 2.375 ,  6.1875,  3.75  , ...,     nan,     nan,     nan])), b'PHI': (DataBlockHdr(type=b'D', name=b'PHI', reserved=0, num_gates=1192, first_gate=2.125, gate_width=0.25, tover=5.0, snr_thresh=1.6, recombined=None, data_size='H', scale=2.8361001014709473, offset=2.0), array([ 32.79150829,  41.60642988,  30.32333025, ...,          nan,
                    nan,          nan])), b'RHO': (DataBlockHdr(type=b'D', name=b'RHO', reserved=0, num_gates=1192, first_gate=2.125, gate_width=0.25, tover=5.0, snr_thresh=1.6, recombined=None, data_size='B', scale=300.0, offset=-60.5), array([ 0.995     ,  0.95833333,  0.99833333, ...,         nan,
                   nan,         nan]))})



.. code-block:: python


    # Pull data out of the file
    sweep = 0

    # First item in ray is header, which has azimuth angle
    az = np.array([ray[0].az_angle for ray in f.sweeps[sweep]])

    # 5th item is a dict mapping a var name (byte string) to a tuple
    # of (header, data array)
    ref_hdr = f.sweeps[sweep][0][4][b'REF'][0]
    ref_range = np.arange(ref_hdr.num_gates) * ref_hdr.gate_width + ref_hdr.first_gate
    ref = np.array([ray[4][b'REF'][1] for ray in f.sweeps[sweep]])

    rho_hdr = f.sweeps[sweep][0][4][b'RHO'][0]
    rho_range = (np.arange(rho_hdr.num_gates + 1) - 0.5) * rho_hdr.gate_width + rho_hdr.first_gate
    rho = np.array([ray[4][b'RHO'][1] for ray in f.sweeps[sweep]])








.. code-block:: python

    fig, axes = plt.subplots(1, 2, figsize=(15, 8))
    add_metpy_logo(fig, 1200, 85, size='large')
    for var_data, var_range, ax in zip((ref, rho), (ref_range, rho_range), axes):
        # Turn into an array, then mask
        data = np.ma.array(var_data)
        data[np.isnan(data)] = np.ma.masked

        # Convert az,range to x,y
        xlocs = var_range * np.sin(np.deg2rad(az[:, np.newaxis]))
        ylocs = var_range * np.cos(np.deg2rad(az[:, np.newaxis]))

        # Plot the data
        cmap = ctables.registry.get_colortable('viridis')
        ax.pcolormesh(xlocs, ylocs, data, cmap=cmap)
        ax.set_aspect('equal', 'datalim')
        ax.set_xlim(-40, 20)
        ax.set_ylim(-30, 30)

    plt.show()



.. image:: /examples/formats/images/sphx_glr_NEXRAD_Level_2_File_001.png
    :align: center




**Total running time of the script:** ( 0 minutes  4.758 seconds)



.. only :: html

 .. container:: sphx-glr-footer


  .. container:: sphx-glr-download

     :download:`Download Python source code: NEXRAD_Level_2_File.py <NEXRAD_Level_2_File.py>`



  .. container:: sphx-glr-download

     :download:`Download Jupyter notebook: NEXRAD_Level_2_File.ipynb <NEXRAD_Level_2_File.ipynb>`


.. only:: html

 .. rst-class:: sphx-glr-signature

    `Gallery generated by Sphinx-Gallery <https://sphinx-gallery.readthedocs.io>`_