In this notebook Doppler Velocity data from the ARM C-band SAPR radar is read using Py-ART and dealiased using BALTRAD.
retrieve data from s3 bucket¶
import os
import urllib.request
from pathlib import Path
# Set the URL for the cloud
URL = "https://js2.jetstream-cloud.org:8001/"
path = "pythia/radar/erad2024/baltrad/pyart2baltrad"
!mkdir -p data
files = ["sgpcsaprppi_20110520095101.nc"]
for file in files:
file0 = os.path.join(path, file)
name = os.path.join("data", Path(file).name)
if not os.path.exists(name):
print(f"downloading, {name}")
urllib.request.urlretrieve(f"{URL}{file0}", name)downloading, data/sgpcsaprppi_20110520095101.nc
%matplotlib inlineImport the necessary modules
import pyart
import baltrad_pyart_bridge as bridge # routines to pass data from Py-ART to BALTRAD
import _dealias # BALTRAD's dealiasing module
## You are using the Python ARM Radar Toolkit (Py-ART), an open source
## library for working with weather radar data. Py-ART is partly
## supported by the U.S. Department of Energy as part of the Atmospheric
## Radiation Measurement (ARM) Climate Research Facility, an Office of
## Science user facility.
##
## If you use this software to prepare a publication, please cite:
##
## JJ Helmus and SM Collis, JORS 2016, doi: 10.5334/jors.119
Read in the data using Py-ART
radar = pyart.io.read("data/sgpcsaprppi_20110520095101.nc")Examine the velocity data using Py-ART Display object.
display = pyart.graph.RadarDisplay(radar)
nyquist_velocity = radar.instrument_parameters["nyquist_velocity"]["data"][0]
display.plot_ppi(
"velocity", 1, colorbar_label="m/s", vmin=-nyquist_velocity, vmax=nyquist_velocity
)
Convert the radar data into a RaveIO object with the velocity data having the correct name.
vel_data = radar.fields["velocity"]["data"]
radar.add_field_like("velocity", "VRAD", vel_data)
rio = bridge.radar2raveio(radar)Perform Doppler velocity dealiasing using BALTRAD.
ret = _dealias.dealias(rio.object)
print("This first scan is dealiased:"), _dealias.dealiased(rio.object.getScan(0))This first scan is dealiased:
(None, False)Add the dealiased velocity field to the origin Py-ART radar object.
temp = bridge.raveio2radar(rio)
if "dealiased_velocity" in radar.fields:
radar.fields.pop("dealiased_velocity")
radar.add_field_like("velocity", "dealiased_velocity", temp.fields["VRAD"]["data"])Plot the dealiased velocities.
display.plot_ppi(
"dealiased_velocity",
1,
colorbar_label="m/s",
vmin=-2 * nyquist_velocity,
vmax=2 * nyquist_velocity,
)