Example of a wind retrieval in a tornado over Sydney#
This shows an example of how to retrieve winds from 4 radars over Sydney.
We use smoothing to decrease the magnitude of the updraft in the region of the mesocyclone. The reduction of noise also helps the solution converge much faster since the cost function is smoother and therefore less susecptible to find a local minimum that is in noise.
The observational constraint is reduced to 0.01 from the usual 1 because we are factoring in many more data points as we are using 4 radars instead of the two in the Darwin example.
This example uses pooch to download the data files.
import pydda
import matplotlib.pyplot as plt
import numpy as np
grid1_path = pydda.tests.get_sample_file("grid1_sydney.nc")
grid2_path = pydda.tests.get_sample_file("grid2_sydney.nc")
grid3_path = pydda.tests.get_sample_file("grid3_sydney.nc")
grid4_path = pydda.tests.get_sample_file("grid4_sydney.nc")
grid1 = pydda.io.read_grid(grid1_path)
grid2 = pydda.io.read_grid(grid2_path)
grid3 = pydda.io.read_grid(grid3_path)
grid4 = pydda.io.read_grid(grid4_path)
# Set initialization and do retrieval
grid1 = pydda.initialization.make_constant_wind_field(grid1, vel_field="VRADH_corr")
new_grids, _ = pydda.retrieval.get_dd_wind_field(
[grid1, grid2, grid3, grid4],
Co=1e-2,
Cm=256.0,
Cx=10,
Cy=10,
Cz=10,
vel_name="VRADH_corr",
refl_field="DBZH",
mask_outside_opt=True,
wind_tol=0.5,
max_iterations=200,
engine="scipy",
)
# Make a neat plot
fig = plt.figure(figsize=(10, 7))
ax = pydda.vis.plot_horiz_xsection_quiver_map(
new_grids,
background_field="DBZH",
level=3,
show_lobes=False,
bg_grid_no=3,
vmin=0,
vmax=60,
quiverkey_len=20.0,
w_vel_contours=[1.0, 3.0, 5.0, 10.0, 20.0],
quiver_spacing_x_km=2.0,
quiver_spacing_y_km=2.0,
quiverkey_loc="top",
colorbar_contour_flag=True,
cmap="ChaseSpectral",
)
ax.set_xticks(np.arange(150.5, 153, 0.1))
ax.set_yticks(np.arange(-36, -32.0, 0.1))
ax.set_xlim([151.0, 151.35])
ax.set_ylim([-34.15, -33.9])
plt.show()
## 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 Office of Science as part of
## the Atmospheric Radiation Measurement (ARM) 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
Welcome to PyDDA 2.5.0
If you are using PyDDA in your publications, please cite:
Jackson et al. (2020) Journal of Open Research Science
Detecting Jax...
Jax/JaxOpt are not installed on your system, unable to use Jax engine.
Detecting TensorFlow...
Unable to load both TensorFlow and tensorflow-probability. TensorFlow engine disabled.
No module named 'tensorflow'
False
Calculating weights for radars 0 and 1
Calculating weights for radars 0 and 2
Calculating weights for radars 0 and 3
Calculating weights for radars 1 and 0
Calculating weights for radars 1 and 2
Calculating weights for radars 1 and 3
Calculating weights for radars 2 and 0
Calculating weights for radars 2 and 1
Calculating weights for radars 2 and 3
Calculating weights for radars 3 and 0
Calculating weights for radars 3 and 1
Calculating weights for radars 3 and 2
Calculating weights for models...
Starting solver
rmsVR = 7.359750110231316
Total points: 399749
The max of w_init is 0.0
Total number of model points: 0
Nfeval | Jvel | Jmass | Jsmooth | Jbg | Jvort | Jmodel | Jpoint | Max w
0|4080.4252| 0.0000| 0.0000| 0.0000| 0.0000| 0.0000| 0.0000| 0.0000
The gradient of the cost functions is 0.1119091690376132
Nfeval | Jvel | Jmass | Jsmooth | Jbg | Jvort | Jmodel | Jpoint | Max w
10| 92.4335| 17.0200| 0.0001| 0.0000| 0.0000| 0.0000| 0.0000| 48.1870
Max change in w: nan
---------------------------------------------------------------------------
KeyboardInterrupt Traceback (most recent call last)
Cell In[1], line 17
13 grid4 = pydda.io.read_grid(grid4_path)
14
15 # Set initialization and do retrieval
16 grid1 = pydda.initialization.make_constant_wind_field(grid1, vel_field="VRADH_corr")
---> 17 new_grids, _ = pydda.retrieval.get_dd_wind_field(
18 [grid1, grid2, grid3, grid4],
19 Co=1e-2,
20 Cm=256.0,
File ~/work/PyDDA/PyDDA/pydda/retrieval/wind_retrieve.py:1587, in get_dd_wind_field(Grids, u_init, v_init, w_init, engine, **kwargs)
1580 w_init = new_grids[0]["w"].values.squeeze()
1582 if (
1583 engine.lower() == "scipy"
1584 or engine.lower() == "jax"
1585 or engine.lower() == "auglag"
1586 ):
-> 1587 return _get_dd_wind_field_scipy(
1588 new_grids, u_init, v_init, w_init, engine, **kwargs
1589 )
1590 elif engine.lower() == "tensorflow":
1591 return _get_dd_wind_field_tensorflow(
1592 new_grids, u_init, v_init, w_init, **kwargs
1593 )
File ~/work/PyDDA/PyDDA/pydda/retrieval/wind_retrieve.py:667, in _get_dd_wind_field_scipy(Grids, u_init, v_init, w_init, engine, points, vel_name, refl_field, u_back, v_back, z_back, frz, Co, Cm, Cx, Cy, Cz, Cb, Cv, Cmod, Cpoint, cvtol, gtol, Jveltol, Ut, Vt, low_pass_filter, mask_outside_opt, weights_obs, weights_model, weights_bg, max_iterations, mask_w_outside_opt, filter_type, filter_window, filter_order, leise_nstep, min_bca, max_bca, upper_bc, above, model_fields, output_cost_functions, roi, wind_tol, tolerance, const_boundary_cond, max_wind_mag, parallel)
665 parameters.print_out = False
666 if engine.lower() == "scipy":
--> 667 winds = fmin_l_bfgs_b(
668 J_function,
669 winds,
670 args=(parameters,),
671 maxiter=max_iterations,
672 pgtol=tolerance,
673 bounds=bounds,
674 fprime=grad_J,
675 callback=_vert_velocity_callback,
676 )
677 else:
679 def loss_and_gradient(x):
File /usr/share/miniconda/envs/pydda-docs/lib/python3.14/site-packages/scipy/optimize/_lbfgsb_py.py:259, in fmin_l_bfgs_b(func, x0, fprime, args, approx_grad, bounds, m, factr, pgtol, epsilon, maxfun, maxiter, callback, maxls)
249 callback = _wrap_callback(callback)
250 opts = {'maxcor': m,
251 'ftol': factr * np.finfo(float).eps,
252 'gtol': pgtol,
(...) 256 'callback': callback,
257 'maxls': maxls}
--> 259 res = _minimize_lbfgsb(fun, x0, args=args, jac=jac, bounds=bounds,
260 **opts)
261 d = {'grad': res['jac'],
262 'task': res['message'],
263 'funcalls': res['nfev'],
264 'nit': res['nit'],
265 'warnflag': res['status']}
266 f = res['fun']
File /usr/share/miniconda/envs/pydda-docs/lib/python3.14/site-packages/scipy/optimize/_lbfgsb_py.py:420, in _minimize_lbfgsb(fun, x0, args, jac, bounds, maxcor, ftol, gtol, eps, maxfun, maxiter, callback, maxls, finite_diff_rel_step, workers, **unknown_options)
412 _lbfgsb.setulb(m, x, low_bnd, upper_bnd, nbd, f, g, factr, pgtol, wa,
413 iwa, task, lsave, isave, dsave, maxls, ln_task)
415 if task[0] == 3:
416 # The minimization routine wants f and g at the current x.
417 # Note that interruptions due to maxfun are postponed
418 # until the completion of the current minimization iteration.
419 # Overwrite f and g:
--> 420 f, g = func_and_grad(x)
421 elif task[0] == 1:
422 # new iteration
423 n_iterations += 1
File /usr/share/miniconda/envs/pydda-docs/lib/python3.14/site-packages/scipy/optimize/_differentiable_functions.py:413, in ScalarFunction.fun_and_grad(self, x)
411 self._update_x(x)
412 self._update_fun()
--> 413 self._update_grad()
414 return self.f, self.g
File /usr/share/miniconda/envs/pydda-docs/lib/python3.14/site-packages/scipy/optimize/_differentiable_functions.py:375, in ScalarFunction._update_grad(self)
373 if self._orig_grad in FD_METHODS:
374 self._update_fun()
--> 375 self.g = self._wrapped_grad(self.x, f0=self.f)
376 self.g_updated = True
File /usr/share/miniconda/envs/pydda-docs/lib/python3.14/site-packages/scipy/optimize/_differentiable_functions.py:39, in _ScalarGradWrapper.__call__(self, x, f0, **kwds)
35 def __call__(self, x, f0=None, **kwds):
36 # Send a copy because the user may overwrite it.
37 # The user of this class might want `x` to remain unchanged.
38 if callable(self.grad):
---> 39 g = np.atleast_1d(self.grad(np.copy(x), *self.args))
40 elif self.grad in FD_METHODS:
41 g, dct = approx_derivative(
42 self.fun,
43 x,
44 f0=f0,
45 **self.finite_diff_options,
46 )
File ~/work/PyDDA/PyDDA/pydda/cost_functions/cost_functions.py:522, in grad_J(winds, parameters)
520 if parameters.parallel:
521 futures = []
--> 522 with ThreadPoolExecutor() as pool:
523 futures.append(
524 pool.submit(
525 _cost_functions_numpy.calculate_grad_radial_vel,
(...) 539 )
540 )
541 if parameters.Cm > 0:
File /usr/share/miniconda/envs/pydda-docs/lib/python3.14/concurrent/futures/_base.py:673, in Executor.__exit__(self, exc_type, exc_val, exc_tb)
672 def __exit__(self, exc_type, exc_val, exc_tb):
--> 673 self.shutdown(wait=True)
674 return False
File /usr/share/miniconda/envs/pydda-docs/lib/python3.14/concurrent/futures/thread.py:273, in ThreadPoolExecutor.shutdown(self, wait, cancel_futures)
271 if wait:
272 for t in self._threads:
--> 273 t.join()
File /usr/share/miniconda/envs/pydda-docs/lib/python3.14/threading.py:1133, in Thread.join(self, timeout)
1130 if timeout is not None:
1131 timeout = max(timeout, 0)
-> 1133 self._os_thread_handle.join(timeout)
KeyboardInterrupt: