PySDM

Introduction

pysdm logo

PySDM offers a set of building blocks for development of atmospheric cloud simulation systems revolving around the particle-based microphysics modelling concept and the Super-Droplet Method algorithm (Shima et al. 2009) for numerically tackling the probabilistic representation of particle coagulation.

For details on PySDM dependencies and installation procedures, see project docs homepage.

Below, a set of basic usage examples in Python, Julia and Matlab is provided as a tutorial More elaborate examples reproducing results from literature, engineered in Python and accompanied by Jupyter notebooks are maintained in the PySDM-examples package.

Tutorials

Hello-world coalescence example in Python, Julia and Matlab

In order to depict the PySDM API with a practical example, the following listings provide sample code roughly reproducing the Figure 2 from Shima et al. 2009 paper using PySDM from Python, Julia and Matlab. It is a Coalescence-only set-up in which the initial particle size spectrum is Exponential and is deterministically sampled to match the condition of each super-droplet having equal initial multiplicity:

Julia (click to expand)

using Pkg
Pkg.add("PyCall")
Pkg.add("Plots")
Pkg.add("PlotlyJS")

using PyCall
si = pyimport("PySDM.physics").si
ConstantMultiplicity = pyimport("PySDM.initialisation.sampling.spectral_sampling").ConstantMultiplicity
Exponential = pyimport("PySDM.initialisation.spectra").Exponential

n_sd = 2^15
initial_spectrum = Exponential(norm_factor=8.39e12, scale=1.19e5 * si.um^3)
attributes = Dict()
attributes["volume"], attributes["multiplicity"] = ConstantMultiplicity(spectrum=initial_spectrum).sample(n_sd)

Matlab (click to expand)

si = py.importlib.import_module('PySDM.physics').si;
ConstantMultiplicity = py.importlib.import_module('PySDM.initialisation.sampling.spectral_sampling').ConstantMultiplicity;
Exponential = py.importlib.import_module('PySDM.initialisation.spectra').Exponential;

n_sd = 2^15;
initial_spectrum = Exponential(pyargs(...
    'norm_factor', 8.39e12, ...
    'scale', 1.19e5 * si.um ^ 3 ...
));
tmp = ConstantMultiplicity(initial_spectrum).sample(int32(n_sd));
attributes = py.dict(pyargs('volume', tmp{1}, 'multiplicity', tmp{2}));

Python (click to expand)

from PySDM.physics import si
from PySDM.initialisation.sampling.spectral_sampling import ConstantMultiplicity
from PySDM.initialisation.spectra.exponential import Exponential

n_sd = 2 ** 15
initial_spectrum = Exponential(norm_factor=8.39e12, scale=1.19e5 * si.um ** 3)
attributes = {}
attributes['volume'], attributes['multiplicity'] = ConstantMultiplicity(initial_spectrum).sample(n_sd)

The key element of the PySDM interface is the Particulator class instances of which are used to manage the system state and control the simulation. Instantiation of the Particulator class is handled by the Builder as exemplified below:

Julia (click to expand)

Builder = pyimport("PySDM").Builder
Box = pyimport("PySDM.environments").Box
Coalescence = pyimport("PySDM.dynamics").Coalescence
Golovin = pyimport("PySDM.dynamics.collisions.collision_kernels").Golovin
CPU = pyimport("PySDM.backends").CPU
ParticleVolumeVersusRadiusLogarithmSpectrum = pyimport("PySDM.products").ParticleVolumeVersusRadiusLogarithmSpectrum

radius_bins_edges = 10 .^ range(log10(10*si.um), log10(5e3*si.um), length=32)

env = Box(dt=1 * si.s, dv=1e6 * si.m^3)
builder = Builder(n_sd=n_sd, backend=CPU(), environment=env)
builder.add_dynamic(Coalescence(collision_kernel=Golovin(b=1.5e3 / si.s)))
products = [ParticleVolumeVersusRadiusLogarithmSpectrum(radius_bins_edges=radius_bins_edges, name="dv/dlnr")]
particulator = builder.build(attributes, products)

Matlab (click to expand)

Builder = py.importlib.import_module('PySDM').Builder;
Box = py.importlib.import_module('PySDM.environments').Box;
Coalescence = py.importlib.import_module('PySDM.dynamics').Coalescence;
Golovin = py.importlib.import_module('PySDM.dynamics.collisions.collision_kernels').Golovin;
CPU = py.importlib.import_module('PySDM.backends').CPU;
ParticleVolumeVersusRadiusLogarithmSpectrum = py.importlib.import_module('PySDM.products').ParticleVolumeVersusRadiusLogarithmSpectrum;

radius_bins_edges = logspace(log10(10 * si.um), log10(5e3 * si.um), 32);

env = Box(pyargs('dt', 1 * si.s, 'dv', 1e6 * si.m ^ 3));
builder = Builder(pyargs('n_sd', int32(n_sd), 'backend', CPU(), 'environment', env));
builder.add_dynamic(Coalescence(pyargs('collision_kernel', Golovin(1.5e3 / si.s))));
products = py.list({ ParticleVolumeVersusRadiusLogarithmSpectrum(pyargs( ...
  'radius_bins_edges', py.numpy.array(radius_bins_edges), ...
  'name', 'dv/dlnr' ...
)) });
particulator = builder.build(attributes, products);

Python (click to expand)

import numpy as np
from PySDM import Builder
from PySDM.environments import Box
from PySDM.dynamics import Coalescence
from PySDM.dynamics.collisions.collision_kernels import Golovin
from PySDM.backends import CPU
from PySDM.products import ParticleVolumeVersusRadiusLogarithmSpectrum

radius_bins_edges = np.logspace(np.log10(10 * si.um), np.log10(5e3 * si.um), num=32)

env = Box(dt=1 * si.s, dv=1e6 * si.m ** 3)
builder = Builder(n_sd=n_sd, backend=CPU(), environment=env)
builder.add_dynamic(Coalescence(collision_kernel=Golovin(b=1.5e3 / si.s)))
products = [ParticleVolumeVersusRadiusLogarithmSpectrum(radius_bins_edges=radius_bins_edges, name='dv/dlnr')]
particulator = builder.build(attributes, products)

The backend argument may be set to CPU or GPU what translates to choosing the multi-threaded backend or the GPU-resident computation mode, respectively. The employed Box environment corresponds to a zero-dimensional framework (particle positions are not considered). The vectors of particle multiplicities n and particle volumes v are used to initialise super-droplet attributes. The Coalescence Monte-Carlo algorithm (Super Droplet Method) is registered as the only dynamic in the system. Finally, the build() method is used to obtain an instance of Particulator which can then be used to control time-stepping and access simulation state.

The run(nt) method advances the simulation by nt timesteps. In the listing below, its usage is interleaved with plotting logic which displays a histogram of particle mass distribution at selected timesteps:

Julia (click to expand)

using Plots; plotlyjs()

for step = 0:1200:3600
    particulator.run(step - particulator.n_steps)
    plot!(
        radius_bins_edges[1:end-1] / si.um,
        particulator.formulae.particle_shape_and_density.volume_to_mass(
            particulator.products["dv/dlnr"].get()[:]
        )/ si.g,
        linetype=:steppost,
        xaxis=:log,
        xlabel="particle radius [µm]",
        ylabel="dm/dlnr [g/m^3/(unit dr/r)]",
        label="t = $step s"
    )
end
savefig("plot.svg")

Matlab (click to expand)

for step = 0:1200:3600
    particulator.run(int32(step - particulator.n_steps));
    x = radius_bins_edges / si.um;
    y = particulator.formulae.particle_shape_and_density.volume_to_mass( ...
        particulator.products{"dv/dlnr"}.get() ...
    ) / si.g;
    stairs(...
        x(1:end-1), ...
        double(py.array.array('d',py.numpy.nditer(y))), ...
        'DisplayName', sprintf("t = %d s", step) ...
    );
    hold on
end
hold off
set(gca,'XScale','log');
xlabel('particle radius [µm]')
ylabel("dm/dlnr [g/m^3/(unit dr/r)]")
legend()

Python (click to expand)

from matplotlib import pyplot

for step in [0, 1200, 2400, 3600]:
    particulator.run(step - particulator.n_steps)
    pyplot.step(
        x=radius_bins_edges[:-1] / si.um,
        y=particulator.formulae.particle_shape_and_density.volume_to_mass(
            particulator.products['dv/dlnr'].get()[0]
        ) / si.g,
        where='post', label=f"t = {step}s"
    )

pyplot.xscale('log')
pyplot.xlabel('particle radius [µm]')
pyplot.ylabel("dm/dlnr [g/m$^3$/(unit dr/r)]")
pyplot.legend()
pyplot.savefig('readme.png')

The resultant plot (generated with the Python code) looks as follows:

plot

The component submodules used to create this simulation are visualized below:

 graph
    COAL[":Coalescence"] --->|passed as arg to| BUILDER_ADD_DYN(["Builder.add_dynamic()"])
    BUILDER_INSTANCE["builder :Builder"] -...-|has a method| BUILDER_BUILD(["Builder.build()"])
    ATTRIBUTES[attributes: dict] -->|passed as arg to| BUILDER_BUILD
    N_SD["n_sd :int"] ---->|passed as arg to| BUILDER_INIT
    BUILDER_INIT(["Builder.__init__()"]) --->|instantiates| BUILDER_INSTANCE
    BUILDER_INSTANCE -..-|has a method| BUILDER_ADD_DYN(["Builder.add_dynamic()"])
    ENV_INIT(["Box.__init__()"]) -->|instantiates| ENV
    DT[dt :float] -->|passed as arg to| ENV_INIT
    DV[dv :float] -->|passed as arg to| ENV_INIT
    ENV[":Box"] -->|passed as arg to| BUILDER_INIT
    B["b: float"] --->|passed as arg to| KERNEL_INIT(["Golovin.__init__()"])
    KERNEL_INIT -->|instantiates| KERNEL
    KERNEL[collision_kernel: Golovin] -->|passed as arg to| COAL_INIT(["Coalesncence.__init__()"])
    COAL_INIT -->|instantiates| COAL
    PRODUCTS[products: list] ----->|passed as arg to| BUILDER_BUILD
    NORM_FACTOR[norm_factor: float]-->|passed as arg to| EXP_INIT
    SCALE[scale: float]-->|passed as arg to| EXP_INIT
    EXP_INIT(["Exponential.__init__()"]) -->|instantiates| IS
    IS["initial_spectrum :Exponential"] -->|passed as arg to| CM_INIT
    CM_INIT(["ConstantMultiplicity.__init__()"]) -->|instantiates| CM_INSTANCE
    CM_INSTANCE[":ConstantMultiplicity"] -.-|has a method| SAMPLE
    SAMPLE(["ConstantMultiplicity.sample()"]) -->|returns| n
    SAMPLE -->|returns| volume
    n -->|added as element of| ATTRIBUTES
    PARTICULATOR_INSTANCE -.-|has a method| PARTICULATOR_RUN(["Particulator.run()"])
    volume -->|added as element of| ATTRIBUTES
    BUILDER_BUILD -->|returns| PARTICULATOR_INSTANCE["particulator :Particulator"]
    PARTICULATOR_INSTANCE -.-|has a field| PARTICULATOR_PROD(["Particulator.products:dict"])
    BACKEND_INSTANCE["backend :CPU"] ---->|passed as arg to| BUILDER_INIT
    PRODUCTS -.-|accessible via| PARTICULATOR_PROD
    NP_LOGSPACE(["np.logspace()"]) -->|returns| EDGES
    EDGES[radius_bins_edges: np.ndarray] -->|passed as arg to| SPECTRUM_INIT
    SPECTRUM_INIT["ParticleVolumeVersusRadiusLogarithmSpectrum.__init__()"] -->|instantiates| SPECTRUM
    SPECTRUM[":ParticleVolumeVersusRadiusLogarithmSpectrum"] -->|added as element of| PRODUCTS

    click COAL "https://open-atmos.github.io/PySDM/PySDM/dynamics/collisions/collision.html#Coalescence"
    click BUILDER_INSTANCE "https://open-atmos.github.io/PySDM/PySDM/builder.html"
    click BUILDER_INIT "https://open-atmos.github.io/PySDM/PySDM/builder.html"
    click BUILDER_ADD_DYN "https://open-atmos.github.io/PySDM/PySDM/builder.html"
    click ENV_INIT "https://open-atmos.github.io/PySDM/PySDM/environments.html"
    click ENV "https://open-atmos.github.io/PySDM/PySDM/environments.html"
    click KERNEL_INIT "https://open-atmos.github.io/PySDM/PySDM/dynamics/collisions/collision_kernels.html"
    click KERNEL "https://open-atmos.github.io/PySDM/PySDM/dynamics/collisions/collision_kernels.html"
    click EXP_INIT "https://open-atmos.github.io/PySDM/PySDM/initialisation/spectra.html"
    click IS "https://open-atmos.github.io/PySDM/PySDM/initialisation/spectra.html"
    click CM_INIT "https://open-atmos.github.io/PySDM/PySDM/initialisation/sampling/spectral_sampling.html"
    click CM_INSTANCE "https://open-atmos.github.io/PySDM/PySDM/initialisation/sampling/spectral_sampling.html"
    click SAMPLE "https://open-atmos.github.io/PySDM/PySDM/initialisation/sampling/spectral_sampling.html"
    click PARTICULATOR_INSTANCE "https://open-atmos.github.io/PySDM/PySDM/particulator.html"
    click BACKEND_INSTANCE "https://open-atmos.github.io/PySDM/PySDM/backends/numba.html"
    click BUILDER_BUILD "https://open-atmos.github.io/PySDM/PySDM/builder.html"
    click NP_LOGSPACE "https://numpy.org/doc/stable/reference/generated/numpy.logspace.html"
    click SPECTRUM_INIT "https://open-atmos.github.io/PySDM/PySDM/products/size_spectral/particle_volume_versus_radius_logarithm_spectrum.html"
    click SPECTRUM "https://open-atmos.github.io/PySDM/PySDM/products/size_spectral/particle_volume_versus_radius_logarithm_spectrum.html"

Hello-world condensation example in Python, Julia and Matlab

In the following example, a condensation-only setup is used with the adiabatic Parcel environment. An initial Lognormal spectrum of dry aerosol particles is first initialised to equilibrium wet size for the given initial humidity. Subsequent particle growth due to Condensation of water vapour (coupled with the release of latent heat) causes a subset of particles to activate into cloud droplets. Results of the simulation are plotted against vertical ParcelDisplacement and depict the evolution of PeakSupersaturation, EffectiveRadius, ParticleConcentration and the WaterMixingRatio.

Julia (click to expand)

using PyCall
using Plots; plotlyjs()
si = pyimport("PySDM.physics").si
spectral_sampling = pyimport("PySDM.initialisation.sampling").spectral_sampling
discretise_multiplicities = pyimport("PySDM.initialisation").discretise_multiplicities
Lognormal = pyimport("PySDM.initialisation.spectra").Lognormal
equilibrate_wet_radii = pyimport("PySDM.initialisation").equilibrate_wet_radii
CPU = pyimport("PySDM.backends").CPU
AmbientThermodynamics = pyimport("PySDM.dynamics").AmbientThermodynamics
Condensation = pyimport("PySDM.dynamics").Condensation
Parcel = pyimport("PySDM.environments").Parcel
Builder = pyimport("PySDM").Builder
Formulae = pyimport("PySDM").Formulae
products = pyimport("PySDM.products")

env = Parcel(
    dt=.25 * si.s,
    mass_of_dry_air=1e3 * si.kg,
    p0=1122 * si.hPa,
    initial_water_vapour_mixing_ratio=20 * si.g / si.kg,
    T0=300 * si.K,
    w= 2.5 * si.m / si.s
)
spectrum = Lognormal(norm_factor=1e4/si.mg, m_mode=50*si.nm, s_geom=1.4)
kappa = .5 * si.dimensionless
cloud_range = (.5 * si.um, 25 * si.um)
output_interval = 4
output_points = 40
n_sd = 256

formulae = Formulae()
builder = Builder(backend=CPU(formulae), n_sd=n_sd, environment=env)
builder.add_dynamic(AmbientThermodynamics())
builder.add_dynamic(Condensation())

r_dry, specific_concentration = spectral_sampling.Logarithmic(spectrum).sample(n_sd)
v_dry = formulae.trivia.volume(radius=r_dry)
r_wet = equilibrate_wet_radii(r_dry=r_dry, environment=builder.particulator.environment, kappa_times_dry_volume=kappa * v_dry)

attributes = Dict()
attributes["multiplicity"] = discretise_multiplicities(specific_concentration * env.mass_of_dry_air)
attributes["dry volume"] = v_dry
attributes["kappa times dry volume"] = kappa * v_dry
attributes["volume"] = formulae.trivia.volume(radius=r_wet)

particulator = builder.build(attributes, products=[
    products.PeakSupersaturation(name="S_max", unit="%"),
    products.EffectiveRadius(name="r_eff", unit="um", radius_range=cloud_range),
    products.ParticleConcentration(name="n_c_cm3", unit="cm^-3", radius_range=cloud_range),
    products.WaterMixingRatio(name="liquid water mixing ratio", unit="g/kg", radius_range=cloud_range),
    products.ParcelDisplacement(name="z")
])

cell_id=1
output = Dict()
for (_, product) in particulator.products
    output[product.name] = Array{Float32}(undef, output_points+1)
    output[product.name][1] = product.get()[cell_id]
end

for step = 2:output_points+1
    particulator.run(steps=output_interval)
    for (_, product) in particulator.products
        output[product.name][step] = product.get()[cell_id]
    end
end

plots = []
ylbl = particulator.products["z"].unit
for (_, product) in particulator.products
    if product.name != "z"
        append!(plots, [plot(output[product.name], output["z"], ylabel=ylbl, xlabel=product.unit, title=product.name)])
    end
    global ylbl = ""
end
plot(plots..., layout=(1, length(output)-1))
savefig("parcel.svg")

Matlab (click to expand)

si = py.importlib.import_module('PySDM.physics').si;
spectral_sampling = py.importlib.import_module('PySDM.initialisation.sampling').spectral_sampling;
discretise_multiplicities = py.importlib.import_module('PySDM.initialisation').discretise_multiplicities;
Lognormal = py.importlib.import_module('PySDM.initialisation.spectra').Lognormal;
equilibrate_wet_radii = py.importlib.import_module('PySDM.initialisation').equilibrate_wet_radii;
CPU = py.importlib.import_module('PySDM.backends').CPU;
AmbientThermodynamics = py.importlib.import_module('PySDM.dynamics').AmbientThermodynamics;
Condensation = py.importlib.import_module('PySDM.dynamics').Condensation;
Parcel = py.importlib.import_module('PySDM.environments').Parcel;
Builder = py.importlib.import_module('PySDM').Builder;
Formulae = py.importlib.import_module('PySDM').Formulae;
products = py.importlib.import_module('PySDM.products');

env = Parcel(pyargs( ...
    'dt', .25 * si.s, ...
    'mass_of_dry_air', 1e3 * si.kg, ...
    'p0', 1122 * si.hPa, ...
    'initial_water_vapour_mixing_ratio', 20 * si.g / si.kg, ...
    'T0', 300 * si.K, ...
    'w', 2.5 * si.m / si.s ...
));
spectrum = Lognormal(pyargs('norm_factor', 1e4/si.mg, 'm_mode', 50 * si.nm, 's_geom', 1.4));
kappa = .5;
cloud_range = py.tuple({.5 * si.um, 25 * si.um});
output_interval = 4;
output_points = 40;
n_sd = 256;

formulae = Formulae();
builder = Builder(pyargs('backend', CPU(formulae), 'n_sd', int32(n_sd), 'environment', env));
builder.add_dynamic(AmbientThermodynamics());
builder.add_dynamic(Condensation());

tmp = spectral_sampling.Logarithmic(spectrum).sample(int32(n_sd));
r_dry = tmp{1};
v_dry = formulae.trivia.volume(pyargs('radius', r_dry));
specific_concentration = tmp{2};
r_wet = equilibrate_wet_radii(pyargs(...
    'r_dry', r_dry, ...
    'environment', builder.particulator.environment, ...
    'kappa_times_dry_volume', kappa * v_dry...
));

attributes = py.dict(pyargs( ...
    'multiplicity', discretise_multiplicities(specific_concentration * env.mass_of_dry_air), ...
    'dry volume', v_dry, ...
    'kappa times dry volume', kappa * v_dry, ...
    'volume', formulae.trivia.volume(pyargs('radius', r_wet)) ...
));

particulator = builder.build(attributes, py.list({ ...
    products.PeakSupersaturation(pyargs('name', 'S_max', 'unit', '%')), ...
    products.EffectiveRadius(pyargs('name', 'r_eff', 'unit', 'um', 'radius_range', cloud_range)), ...
    products.ParticleConcentration(pyargs('name', 'n_c_cm3', 'unit', 'cm^-3', 'radius_range', cloud_range)), ...
    products.WaterMixingRatio(pyargs('name', 'liquid water mixing ratio', 'unit', 'g/kg', 'radius_range', cloud_range)) ...
    products.ParcelDisplacement(pyargs('name', 'z')) ...
}));

cell_id = int32(0);
output_size = [output_points+1, length(py.list(particulator.products.keys()))];
output_types = repelem({'double'}, output_size(2));
output_names = [cellfun(@string, cell(py.list(particulator.products.keys())))];
output = table(...
    'Size', output_size, ...
    'VariableTypes', output_types, ...
    'VariableNames', output_names ...
);
for pykey = py.list(keys(particulator.products))
    get = py.getattr(particulator.products{pykey{1}}.get(), '__getitem__');
    key = string(pykey{1});
    output{1, key} = get(cell_id);
end

for i=2:output_points+1
    particulator.run(pyargs('steps', int32(output_interval)));
    for pykey = py.list(keys(particulator.products))
        get = py.getattr(particulator.products{pykey{1}}.get(), '__getitem__');
        key = string(pykey{1});
        output{i, key} = get(cell_id);
    end
end

i=1;
for pykey = py.list(keys(particulator.products))
    product = particulator.products{pykey{1}};
    if string(product.name) ~= "z"
        subplot(1, width(output)-1, i);
        plot(output{:, string(pykey{1})}, output.z, '-o');
        title(string(product.name), 'Interpreter', 'none');
        xlabel(string(product.unit));
    end
    if i == 1
        ylabel(string(particulator.products{"z"}.unit));
    end
    i=i+1;
end
saveas(gcf, "parcel.png");

Python (click to expand)

from matplotlib import pyplot
from PySDM.physics import si
from PySDM.initialisation import discretise_multiplicities, equilibrate_wet_radii
from PySDM.initialisation.spectra import Lognormal
from PySDM.initialisation.sampling import spectral_sampling
from PySDM.backends import CPU
from PySDM.dynamics import AmbientThermodynamics, Condensation
from PySDM.environments import Parcel
from PySDM import Builder, Formulae, products

env = Parcel(
  dt=.25 * si.s,
  mass_of_dry_air=1e3 * si.kg,
  p0=1122 * si.hPa,
  initial_water_vapour_mixing_ratio=20 * si.g / si.kg,
  T0=300 * si.K,
  w=2.5 * si.m / si.s
)
spectrum = Lognormal(norm_factor=1e4 / si.mg, m_mode=50 * si.nm, s_geom=1.5)
kappa = .5 * si.dimensionless
cloud_range = (.5 * si.um, 25 * si.um)
output_interval = 4
output_points = 40
n_sd = 256

formulae = Formulae()
builder = Builder(backend=CPU(formulae), n_sd=n_sd, environment=env)
builder.add_dynamic(AmbientThermodynamics())
builder.add_dynamic(Condensation())

r_dry, specific_concentration = spectral_sampling.Logarithmic(spectrum).sample(n_sd)
v_dry = formulae.trivia.volume(radius=r_dry)
r_wet = equilibrate_wet_radii(r_dry=r_dry, environment=builder.particulator.environment, kappa_times_dry_volume=kappa * v_dry)

attributes = {
  'multiplicity': discretise_multiplicities(specific_concentration * env.mass_of_dry_air),
  'dry volume': v_dry,
  'kappa times dry volume': kappa * v_dry,
  'volume': formulae.trivia.volume(radius=r_wet)
}

particulator = builder.build(attributes, products=[
  products.PeakSupersaturation(name='S_max', unit='%'),
  products.EffectiveRadius(name='r_eff', unit='um', radius_range=cloud_range),
  products.ParticleConcentration(name='n_c_cm3', unit='cm^-3', radius_range=cloud_range),
  products.WaterMixingRatio(name='liquid water mixing ratio', unit='g/kg', radius_range=cloud_range),
  products.ParcelDisplacement(name='z')
])

cell_id = 0
output = {product.name: [product.get()[cell_id]] for product in particulator.products.values()}

for step in range(output_points):
  particulator.run(steps=output_interval)
  for product in particulator.products.values():
    output[product.name].append(product.get()[cell_id])

fig, axs = pyplot.subplots(1, len(particulator.products) - 1, sharey="all")
for i, (key, product) in enumerate(particulator.products.items()):
  if key != 'z':
    axs[i].plot(output[key], output['z'], marker='.')
    axs[i].set_title(product.name)
    axs[i].set_xlabel(product.unit)
    axs[i].grid()
axs[0].set_ylabel(particulator.products['z'].unit)
pyplot.savefig('parcel.svg')

The resultant plot (generated with the Matlab code) looks as follows:

plot

Tutorials from Caltech course

There are currently two tutorial notebooks from the Caltech course on Cloud Microphysics available:

Submodule structure

mindmap
  root((PySDM))
    Builder
    Formulae
    Particulator
    ((attributes))
      (physics)
        DryVolume: ExtensiveAttribute
        Kappa: DerivedAttribute
        ...
      (chemistry)
        Acidity
        ...
      (...)
    ((backends))
      CPU
      GPU
    ((dynamics))
      AqueousChemistry
      Collision
      Condensation
      ...
    ((environments))
      Box
      Parcel
      Kinematic2D
      ...
    ((initialisation))
      (spectra)
        Lognormal
        Exponential
        ...
      (sampling)
        (spectral_sampling)
          ConstantMultiplicity
          UniformRandom
          Logarithmic
          ...
        (...)
      (...)
    ((physics))
      (hygroscopicity)
        KappaKoehler
        ...
      (condensation_coordinate)
        Volume
        VolumeLogarithm
      (...)
    ((products))
      (size_spectral)
        EffectiveRadius
        WaterMixingRatio
        ...
      (ambient_thermodynamics)
        AmbientRelativeHumidity
        ...
      (...)

Contributing, reporting issues, seeking support

See README.md

Related resources and open-source projects

SDM patents (some expired, some withdrawn):

Other SDM implementations:

non-SDM probabilistic particle-based coagulation solvers

Python models with discrete-particle (moving-sectional) representation of particle size spectrum

non-Python cloud microphysics open-source software

 1# pylint:disable=invalid-name
 2"""
 3.. include:: ../docs/markdown/pysdm_landing.md
 4"""
 5
 6from importlib.metadata import PackageNotFoundError, version
 7
 8from PySDM.attributes.impl.attribute_registry import register_attribute
 9
10from . import attributes
11from . import environments, exporters, products
12from .builder import Builder
13from .formulae import Formulae
14from .particulator import Particulator
15
16try:
17    __version__ = version(__name__)
18except PackageNotFoundError:
19    # package is not installed
20    pass