How do I filter radially plotted data by elevation (or latitude/longitude)?

[BlueNalgene]

I want to create a radial plot of cross correlation below a certain altitude threshold. I can easily extract the data to an array using radar.iter_elevation() or hack something together with radar.extract_sweeps(0). Unfortunately, these methods do not fit well in the pyart.graph.RadarDisplay(radar).plot paradigm as far as I can tell. Existing filtering methods exist, but only for fields in the gate data e.g., gatefilter.exclude_above("elevation", 3.0) will fail. How can I make the pretty picture I want to use later for OpenCV?

MWE:

import matplotlib.pyplot as plt
import pyart.graph
import pyart

infile = "./dl/KTLX20250423_010059_V06"
radar = pyart.io.read_nexrad_archive(infile)
# gatefilter = pyart.correct.GateFilter(radar)
# gatefilter.exclude_above("elevation", 3.0) # I want something like this here

display = pyart.graph.RadarDisplay(radar)
fig = plt.figure(figsize=(14, 10))
plot = ['cross_correlation_ratio', "Low Alt Reflections", 0]
ax = fig.add_subplot(1, 1, 1)
display.plot(\
    plot[0], \
    plot[2], \
    ax=ax, \
    title=plot[1], \
    colorbar_label='Rho_HV', \
    axislabels=('East-West distance from radar (km)', 'North-South distance from radar (km)'),
)
plt.show()

[zssherman]

Hi @BlueNalgene , have you tried the top of atmosphere filter?
https://arm-doe.github.io/pyart/API/generated/pyart.filters.GateFilter.exclude_above_toa.html#pyart.filters.GateFilter.exclude_above_toa

Essentially this filter will mask heights above a given height in meters. Might be what you are looking for

[BlueNalgene]

Thanks, this seems like what I want. I can't tell how it should be implemented though. I've been hacking through all of the correct methods, but nothing seems to have what I need to plot the cross correlation coeff with a gatefilter.

[zssherman]

@BlueNalgene You'll want to add the gatefilter to the plotting code, something like:

gatefilter = pyart.correct.GateFilter(radar)
gatefilter.exclude_above_toa(3000)

display.plot(
    plot[0],
    plot[2], 
    ax=ax, 
    title=plot[1],
    gatefilter=gatefilter,
    colorbar_label='Rho_HV', 
    axislabels=('East-West distance from radar (km)', 'North-South distance from radar (km)'),
)

[BlueNalgene]

That was way easier than I was trying to make it. Thank you.

[zssherman]

No problem!