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changes to comp_z #1562

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dopplerchase
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Code for issue #1559, where composite reflectivity code carried artifacts through with poor quality radar data from velocity sweeps. I also made a change to the interpolator because it was flagged as depreciated (e.g., scipy.interpolate.interp2d).

This is now open for comment from the maintainers! Happy to make changes as needed.

Example usage:

compz = pyart.retrieve.composite_reflectivity(radar, field="reflectivity")

image

The code is flexible, and allows you to still have the old functionality through the simple bool:

compz = pyart.retrieve.composite_reflectivity(radar, field="reflectivity",same_nyquist=False)

image

@zssherman
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@dopplerchase Thanks for the PR! The errors seem to be PEP8 fixes.

@@ -9,11 +9,12 @@
from netCDF4 import num2date
from pandas import to_datetime
from scipy.interpolate import interp2d
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Old import should be removed


from pyart.core import Radar


def composite_reflectivity(radar, field="reflectivity", gatefilter=None):
def composite_reflectivity(radar, field="reflectivity", gatefilter=None,same_nyquist=True,nyquist_vector_idx=0):
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space between between the comment and same_

During a volume scan (i.e., file) the PRF (nyqust velocity) can change.
This can create some odd artifacts at times with if data quality is low on certain scans.
To get around this, you can change the code to only take the max of scans with the same nyquist +/- 1 m/s.
Defult this will be on (True), but folks can turn this off.
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Defult to Default

This can create some odd artifacts at times with if data quality is low on certain scans.
To get around this, you can change the code to only take the max of scans with the same nyquist +/- 1 m/s.
Defult this will be on (True), but folks can turn this off.
nyquist_vector_idx: int
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Space around colon


# Apply the interpolation
z = z_interpolator(ranges, azimuth_final)
z = z_interpolator(azimuth_final,ranges)
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space after comma


# if first sweep, create new dim, otherwise concat them up
if sweep == minimum_sweep:
z_stack = copy.deepcopy(z[np.newaxis, :, :])
nyquist_stack = copy.deepcopy(nyquist[np.newaxis,:])
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space after comma

@@ -190,4 +214,4 @@ def composite_reflectivity(radar, field="reflectivity", gatefilter=None):
azimuth,
elevation,
instrument_parameters=instrument_parameters,
)
)
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Remove no newline

@mgrover1
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@dopplerchase - is there anything we can do to help here?

@dopplerchase
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@mgrover1 find me some more time? lol We need to think carefully about Ryan's comments noted on #1559

@mgrover1
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no worries 😄 that is a good point!!

@decadeneo
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I'm glad to hear that someone has encountered a similar bug. When directly using the function pyart.retrieve.composite_reflectivity, I found that the interpolated composite reflectivity values are all NaN. Upon diving into the source code, I was prompted to change the interpolation method. However, when attempting to modify it with alternative interpolation methods, I encountered an error indicating that the number of azimuth angles per layer in my radar data is inconsistent, thereby preventing a smooth interpolation process.

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Composite Z bugs (issue and fix)
4 participants