Hydrometeorclassification - Membershipfunctions

The hydrometeorclassification code is based on the paper by Zrnic et.al 2001 utilizing 2D trapezoidal membership functions based on the paper by Straka et. al 2000 adapted by Evaristo et. al 2013 for X-Band.

import matplotlib.pyplot as plt
import wradlib as wrl
import xarray as xr

import radarpolarimetry as rp

Precipitation Types

pr_types = dict(wrl.classify.pr_types.values())
for k, v in enumerate(pr_types.items()):
    print(f"{k:02} {' - '.join(v)}")

00 LR - Light Rain
01 MR - Moderate Rain
02 HR - Heavy Rain
03 LD - Large Drops
04 HL - Hail
05 RH - Rain/Hail
06 GH - Graupel/Hail
07 DS - Dry Snow
08 WS - Wet Snow
09 HC - H Crystals
10 VC - V Crystals
11 NP - No Precip

Load 2D Membership Functions

filename = "/radar/wradlib-data/misc/msf_xband_v1.nc"
with rp.rpol_data.open(filename) as f:
    filename = f.name
msf = xr.open_dataset(filename)
display(msf)

<xarray.Dataset> Size: 97kB
Dimensions:  (hmc: 11, idp: 55, trapezoid: 4)
Coordinates:
  * hmc      (hmc) <U2 88B 'LR' 'MR' 'HR' 'LD' 'HL' ... 'GH' 'DS' 'WS' 'HC' 'VC'
  * idp      (idp) float64 440B -10.0 -8.0 -6.0 -4.0 ... 92.0 94.0 96.0 98.0
Dimensions without coordinates: trapezoid
Data variables:
    ZH       (hmc, idp, trapezoid) float64 19kB ...
    ZDR      (hmc, idp, trapezoid) float64 19kB ...
    RHO      (hmc, idp, trapezoid) float64 19kB ...
    KDP      (hmc, idp, trapezoid) float64 19kB ...
    TEMP     (hmc, idp, trapezoid) float64 19kB ...
Attributes:
    version:      1
    title:        2D Membershipfunctions Hydrometeorclassification for XBand
    institution:  Institute of Geosciences, Meteorology Section, University o...
    history:      created by Raquel Evaristo, adapted to netCDF by Kai Mühlbauer
    comment:      created with wradlib

xarray.Dataset

• Dimensions:
  • hmc: 11
  • idp: 55
  • trapezoid: 4
• Coordinates: (2)
  • hmc
    (hmc)
    <U2
    'LR' 'MR' 'HR' ... 'WS' 'HC' 'VC'

    array(['LR', 'MR', 'HR', 'LD', 'HL', 'RH', 'GH', 'DS', 'WS', 'HC', 'VC'],
          dtype='<U2')

  • idp
    (idp)
    float64
    -10.0 -8.0 -6.0 ... 94.0 96.0 98.0

    standard_name :

    radar_equivalent_reflectivity_factor_h

    long_name :

    Equivalent reflectivity factor H

    short_name :

    DBZH

    units :

    dBZ

    array([-10.,  -8.,  -6.,  -4.,  -2.,   0.,   2.,   4.,   6.,   8.,  10.,  12.,
            14.,  16.,  18.,  20.,  22.,  24.,  26.,  28.,  30.,  32.,  34.,  36.,
            38.,  40.,  42.,  44.,  46.,  48.,  50.,  52.,  54.,  56.,  58.,  60.,
            62.,  64.,  66.,  68.,  70.,  72.,  74.,  76.,  78.,  80.,  82.,  84.,
            86.,  88.,  90.,  92.,  94.,  96.,  98.])

• Data variables: (5)
  • ZH
    (hmc, idp, trapezoid)
    float64
    ...

    standard_name :

    radar_equivalent_reflectivity_factor_h

    long_name :

    Equivalent reflectivity factor H

    short_name :

    DBZH

    units :

    dBZ

    [2420 values with dtype=float64]

  • ZDR
    (hmc, idp, trapezoid)
    float64
    ...

    standard_name :

    radar_differential_reflectivity_hv

    long_name :

    Log differential reflectivity H/V

    short_name :

    ZDR

    units :

    dB

    [2420 values with dtype=float64]

  • RHO
    (hmc, idp, trapezoid)
    float64
    ...

    standard_name :

    radar_correlation_coefficient_hv

    long_name :

    Correlation coefficient HV

    short_name :

    RHOHV

    units :

    unitless

    [2420 values with dtype=float64]

  • KDP
    (hmc, idp, trapezoid)
    float64
    ...

    standard_name :

    radar_specific_differential_phase_hv

    long_name :

    Specific differential phase HV

    short_name :

    KDP

    units :

    degrees per kilometer

    [2420 values with dtype=float64]

  • TEMP
    (hmc, idp, trapezoid)
    float64
    ...

    standard_name :

    temperature

    long_name :

    temperature

    short_name :

    t

    units :

    degrees C

    [2420 values with dtype=float64]

• Attributes: (5)

  version :

  1

  title :

  2D Membershipfunctions Hydrometeorclassification for XBand

  institution :

  Institute of Geosciences, Meteorology Section, University of Bonn

  history :

  created by Raquel Evaristo, adapted to netCDF by Kai Mühlbauer

  comment :

  created with wradlib

Plot 2D Membership Functions

minmax = [(0, 50), (-1, 6), (0.0, 1.0), (-5, 35), (-65, 45)]


def plot_msf(hmc):
    fig = plt.figure(figsize=(10, 8))
    t = fig.suptitle(f"{hmc.hmc.values} - {pr_types[hmc.hmc.values.item()]}")
    t.set_y(1.02)
    for k, p in enumerate(hmc.data_vars.values()):
        p = p.where(p != 0)
        ax = fig.add_subplot(3, 2, k + 1)
        p.sel(trapezoid=0).plot(x="idp", c="k", lw=1.0, ax=ax)
        p.sel(trapezoid=1).plot(x="idp", c="k", lw=2.0, ax=ax)
        p.sel(trapezoid=2).plot(x="idp", c="k", lw=2.0, ax=ax)
        p.sel(trapezoid=3).plot(x="idp", c="k", lw=1.0, ax=ax)
        ax.set_xlim((hmc.idp.min(), hmc.idp.max()))
        ax.margins(x=0.05, y=0.05)
        t = ax.set_title(f"{p.long_name}")
        ax.set_ylim(minmax[k])
    fig.tight_layout()

plot_msf(msf.sel(hmc="LR"))

Exercise 1: Plot other Hydrometeor types and discuss

Solution 1: Plot other Hydrometeor types and discuss

for k in pr_types:
    if k == "NP":
        continue
    plot_msf(msf.sel(hmc=k))

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