Do we have any function to calculate Nw if we have Median drop diameter (Do) and reflectivity Z ?

It looks like the current conda package is out of date on conda-forge. It still appears to have the bug that the most recent commit fixed (scattering table IO). I'm not sure who is maintaining, but it would be good to re-issue these packages based on newest code.

When I'm running the example from github, everything works fine, but when I'm running the code with my parameters I'm getting the line: "Process finished with exit code 0" and can't get the results of the calculated array.

The example from github:

scatterer = tmatrix.Scatterer(radius=1.0, wavelength=10.0, m=complex(1.5, 0.5), axis_ratio=1.0/0.6)
scatterer.get_S()
array([[ 9.66435719e-02 +6.79614074e-02j,
6.16862803e-25 +7.07135826e-25j],
[ -6.16862447e-25 -7.07128493e-25j,
-1.01600111e-01 -1.06748868e-01j]])

my code:
scatterer = tmatrix.Scatterer(radius=50, wavelength=5, m=complex(0.1903, 0), axis_ratio=180/100)
scatterer.get_S()

Hi,

there is an error, probably a typo, in the function dsr_bc() in tmatrix_aux: The factor D_eq is missing for the second summand (see for example Bringi and Chandrasekar 2001, equation 7.3).

Regards and thank you for this python interface for the T-matrix method!

I am using radar data in vertical pointing mode so how can i perform scattering simulations in case of vertical incidence ?
scatterer.set_geometry(tmatrix_aux.geom_vert_forw)?

It appears that BinnedDSD and scattering is not playing nicely in the newest version of pytmatrix. As an example the following:
from pytmatrix.tmatrix import Scatterer
from pytmatrix.psd import PSDIntegrator
from pytmatrix import orientation, radar, tmatrix_aux, refractive

scatterer = Scatterer(wavelength=pytmatrix.tmatrix_aux.wl_C,
                                   m=pytmatrix.refractive.m_w_10C[pytmatrix.tmatrix_aux.wl_C])
BinnedDSD = pytmatrix.psd.BinnedPSD([0.1,0.2,0.3,0.4,0.5], [10,10,10,10])
scatterer.psd = BinnedDSD

scatterer.psd_integrator = PSDIntegrator()
scatterer.psd_integrator.axis_ratio_func = lambda D: 1.0 / \
            pytmatrix.tmatrix_aux.dsr_pb(D)
dsr_func = pytmatrix.tmatrix_aux.dsr_pb
scatterer.psd_integrator.D_max = 10.0
scatterer.psd_integrator.geometries = (
            tmatrix_aux.geom_horiz_back, tmatrix_aux.geom_horiz_forw)
scatterer.or_pdf = orientation.gaussian_pdf(20.0)
scatterer.orient = orientation.orient_averaged_fixed
scatterer.psd_integrator.init_scatter_table(scatterer)


radar.refl(scatterer)

gives the error

AttributeError: 'NoneType' object has no attribute 'bin_edges'

> /Users/hard505/anaconda/envs/py36/lib/python3.6/site-packages/pytmatrix/psd.py(243)__eq__()
    241 
    242     def __eq__(self, other):
--> 243         return len(self.bin_edges) == len(other.bin_edges) and \
    244             (self.bin_edges == other.bin_edges).all() and \
    245             (self.bin_psd == other.bin_psd).all()

Hello,

I'm wondering if this code is suitable for both lidar and radar to compute the scattering cross section and extinction cross section in bad weather (such as rain, fog, and dust storms), in other words, whether this code is self-adaption for the Rayleigh scattering and Mie scattering?

Thanks a lot!

• LICENSE.txt in source folder claims to be BSD-3-clause.
• License header in setup.py is MIT

As LICENSE.txt is not distributed with PyPI, people who install from there might assume this package is MIT, whereas people who are installing from GITHUB might assume this is BSD-3-Clause.

Now, what license should be used when redistributing this package?

I have got the amplitude scattering matrix, then how to get volume scattering function or phase function with an incident radiant of none polarization by using this code.? thanks a lot.

I'm very thankful for your work on the T-matrix method.
Because study python is mush more easy than Fortran. It spend me less time to do more works.
My work is use WRF data to simulate Airborne polarimetric weather radar.
Now I'm preparing a paper.I find you add "Chapter 8 Citing the code", I will add your paper in mine.

Thanks again~
Best wishes.
Happy New year 2016

I set m=refractive.ice_refractive('ice_refr.dat')(8.43,0.2) and mu=0(GammaDSD),the other settings are the same as the example given by Wiki which is to compute radar scattering properties for a C-band radar. The result is too small(ref=9.55dBz WhenD0=1.1,Nw=2500)

Why is the reflectivity factor in meters smaller than the normal one 300db, and the one in millimeters larger than the normal one about 60db

Hi, I am running into a problem when i try and create a scatterer with a diameter that is ~40x larger than the wavelength. Is this a bug?

The part of "radar.py" to calculate Specific attenuation (A) means "Ah=8.686wavelengthImag(Shh)", but according to formula(4.7b) in a book named "Polarimetric Doppler Weather Radar Principles and Applications" by V.N.Bringi(which is also the conference of this code), that should be "Ah=-8.686wavelengthImag(Shh)", there is a minus sign difference. So is this part of code wrong?
Thanks for your help!

It's shown that the RCS calculation of particles is based on the Muller Matrix, so the result of calculation should be RCS with unit of 'm^2/m^3', i.e., the RCS in a unit volume. So I'm wondering how to get the single particle's RCS with unit of 'm^2'.

I'm looking forward to your reply. Thank you for your kindness!

Hi @jleinonen ,

When I compute Ah and Av of rain with a prescribed canting angle using the psd_integrator I get exactly the same results for Ah and for Av. In fact the parameter h_pol in radar.Ai(scatterer, h_pol=False) seems to be ignored when using the integrator.

I am missing something or is this indeed a bug in the code?

Cheers,

@jfigui

It would seem that going forward this package might be limited to Python < 3.12, unless the package is updated to account for the new numpy changes. From this page: https://numpy.org/doc/stable/reference/distutils.html

numpy.distutils is deprecated, and will be removed for Python >= 3.12.

Not sure how much work it is to parse this over or if its worth it.

As far as I know, the cross sections are in units of area. But in the code the calculation of extinction cross section is

    2 * scatterer.wavelength * S[1,1].imag

which would give a unit of a length? Can you please provide the reference of this equation? This would be really nice.

Thank you.

Hello,

I would like to inform you that while running "test_tmatrix.run_tests()", I have got the following warning:

test_adaptive_orient (pytmatrix.test.test_tmatrix.TMatrixTests)
Test an adaptive orientation averaging case ... C:\ProgramData\Anaconda3\lib\site-packages\scipy\integrate\quadpack.py:879: IntegrationWarning: The integral is probably divergent, or slowly convergent.
quad_r = quad(f, low, high, args=args, full_output=self.full_output,
C:\ProgramData\Anaconda3\lib\site-packages\scipy\integrate\quadpack.py:879: IntegrationWarning: The algorithm does not converge. Roundoff error is detected
in the extrapolation table. It is assumed that the requested tolerance
cannot be achieved, and that the returned result (if full_output = 1) is
the best which can be obtained.
quad_r = quad(f, low, high, args=args, full_output=self.full_output,
ok

I reported it here, as I am not sure whether this waring is expected.

Best,
BA

Sorry to bother you, but I want to know the effect of scatterer.psd_integrator.geometries = (geom_back, geom_forw)

According to the code of 'radar.py', when the unit of the wavelength is 'm', by using 'Ah = 8.686 x wavelength x Imag[Shh]' , we can get the specific attenuation in 'dB/km', so I guess, the unit of the scattering amplitude the code defines is 'km', is that right?

But if so, then, the unit of RCS is 'km^2/m^3', which seems unreliable.

Thanks for your help and patience!

I try to create a LUT for rain using your code. The code is dedicated for the nadir looking radar so I use the following settings: beta=90,thet0=90,thet=90,angular_integration=True (correct me if it is wrong)
The code works fine with a single scatterer

scatterer = Scatterer(radius=3.0, wavelength=8, m=complex(1.5,0.5), axis_ratio=1.0/0.6, beta=90,thet0=90,thet=90,angular_integration=True)
scatter.asym(scatterer)
0.6983014838870412
np.log10(radar.refl(scatterer))*10
21.354628070158022
np.log10(radar.Zdr(scatterer))*10
0.0

moreover when I define the PSD everything works just fine

scatterer = Scatterer(wavelength=tmatrix_aux.wl_Ka, m=refractive.m_w_10C[tmatrix_aux.wl_C],axis_ratio=1.0/0.6,beta=90.0)
scatterer.psd_integrator = PSDIntegrator()
scatterer.psd_integrator.D_max = 4.0
scatterer.or_pdf = orientation.gaussian_pdf(20.0)
scatterer.orient = orientation.orient_averaged_fixed
scatterer.psd_integrator.num_points=2**3
scatterer.psd_integrator.init_scatter_table(scatterer, verbose=True,
angular_integration=True)

but when I try to get the reflectivity of the ensambe of partiles then I get the following:

10*np.log10(radar.refl(scatterer))
Traceback (most recent call last):

File "", line 1, in 10*np.log10(radar.refl(scatterer))

File "/opt/miniconda3/lib/python3.6/site-packages/pytmatrix/radar.py", line 62, in refl
radar_xsect(scatterer, h_pol)

File "/opt/miniconda3/lib/python3.6/site-packages/pytmatrix/radar.py", line 38, in radar_xsect
Z = scatterer.get_Z()

File "/opt/miniconda3/lib/python3.6/site-packages/pytmatrix/tmatrix.py", line 341, in get_Z
return self.get_SZ()[1]

File "/opt/miniconda3/lib/python3.6/site-packages/pytmatrix/tmatrix.py", line 329, in get_SZ
self.get_geometry())

File "/opt/miniconda3/lib/python3.6/site-packages/pytmatrix/psd.py", line 307, in call
return self.get_SZ(psd, geometry)

File "/opt/miniconda3/lib/python3.6/site-packages/pytmatrix/psd.py", line 334, in get_SZ
return (self._S_dict[geometry], self._Z_dict[geometry])

KeyError: (90.0, 90.0, 0.0, 180.0, 0.0, 90.0)

which suggests that the geometry setting is causing problems

Hello,
I am using this code to calculate scattering coefficient and extinction coefficient. But I find that the execution of the code stops when I try to calculate the T-matrix of a scatterer with a size parameter which is about 80 while the axis_ratio = 1, and the size parameter is reduced to about 18 while the axis_ratio = 3. Is this a bug? Or it's a existing limit of the fortran numerical code?
According to table 1 in the paper named "Capabilities and limitations of a current FORTRAN implementation of the T-matrix method for randomly oriented, rotationally symmetric scatterers" by M. I. Mishchenko, the maximal convergent size parameters seem to be much larger than the limit I find.

By the way, I have tried to increase value of the attribute ndgs in the Scatterer class, but still I can't calculate the T-matrix when size parameter is large.
So, I want to know how large size parameters can this code calculate? And what should I do to calculate T-matrix for larger size parameter?
I'm looking forward to your reply. Thanks for your kindness!
Best,
Lee

The modules written in fortran does not build. After I installed it with pip and with python setup.py install the there are no compiled files and there are no fortran .f files. Can you please provide me the already compiled files? In C one can provide the .c or .h files. I guess that should be possible with fortran as well.

Thank you very much.

I tried installing this package through the pip install pytmatrix method. The .so file failed to compile. However, installing from source after cloning the repo worked.

Running MacOSx 10.11.6
pip 8.1.2