particula.particles.activity_strategies

activity_strategies

Common interface for activity calculations.

Class strategies for activities and vapor pressure over mixture of liquids surface Using Raoult's Law, and strategies ideal, non-ideal, kappa hygroscopic parameterizations.

ActivityIdealMass

Bases: ActivityStrategy

Calculate ideal activity based on mass fractions (Raoult's Law).

• activity : Computes activity from mass concentration, treating mass fractions as ideal.

Examples:

Example Usage

import particula as par
strategy = par.particles.ActivityIdealMass()
a = strategy.activity([0.5, 1.0, 1.5])
# a -> ...

References: - "Raoult's Law," Wikipedia.

activity

activity(mass_concentration: Union[float, NDArray[float64]]) -> Union[float, NDArray[np.float64]]

Calculate the activity of a species based on mass concentration.

Parameters:

• - mass_concentration –

  Concentration of the species in kg/m^3.

Returns:

• Union[float, NDArray[float64]] –
  • Activity of the species, unitless.

Source code in particula/particles/activity_strategies.py

def activity(
    self, mass_concentration: Union[float, NDArray[np.float64]]
) -> Union[float, NDArray[np.float64]]:
    """Calculate the activity of a species based on mass concentration.

    Arguments:
        - mass_concentration : Concentration of the species in kg/m^3.

    Returns:
        - Activity of the species, unitless.
    """
    return get_ideal_activity_mass(mass_concentration=mass_concentration)

ActivityIdealMolar

ActivityIdealMolar(molar_mass: Union[float, NDArray[float64]] = 0.0)

Bases: ActivityStrategy

Calculate ideal activity based on mole fractions (Raoult's Law).

Attributes:

• - (molar_mass) –

  Molar mass of the species in kg/mol.

Methods:

• - activity –

  Computes ideal activity from mass concentration and molar mass.

Examples:

Example Usage

import particula as par
strategy = par.particles.ActivityIdealMolar(molar_mass=0.018)
# mass_concentration in kg/m^3
a = strategy.activity(np.array([1.2, 2.5, 3.0]))
# a -> ...

References

• "Raoult's Law," Wikipedia.

Initialize the ActivityIdealMolar strategy.

Parameters:

• - molar_mass –

  Molar mass in kg/mol.

Source code in particula/particles/activity_strategies.py

def __init__(self, molar_mass: Union[float, NDArray[np.float64]] = 0.0):
    """Initialize the ActivityIdealMolar strategy.

    Arguments:
        - molar_mass : Molar mass in kg/mol.
    """
    self.molar_mass = molar_mass

activity

activity(mass_concentration: Union[float, NDArray[float64]]) -> Union[float, NDArray[np.float64]]

Calculate the activity of a species based on mass concentration.

Parameters:

• - mass_concentration –

  Concentration of the species in kg/m^3.

Returns:

• Union[float, NDArray[float64]] –
  • Activity of the species, unitless.

Source code in particula/particles/activity_strategies.py

def activity(
    self, mass_concentration: Union[float, NDArray[np.float64]]
) -> Union[float, NDArray[np.float64]]:
    """Calculate the activity of a species based on mass concentration.

    Arguments:
        - mass_concentration : Concentration of the species in kg/m^3.

    Returns:
        - Activity of the species, unitless.
    """
    return get_ideal_activity_molar(
        mass_concentration=mass_concentration, molar_mass=self.molar_mass
    )

ActivityIdealVolume

ActivityIdealVolume(density: Union[float, NDArray[float64]] = 0.0)

Bases: ActivityStrategy

Calculate ideal activity based on volume fractions (Raoult's Law).

Attributes:

• - (density) –

  The density of the species in kg/m^3, used to derive volume fractions from mass concentrations.

Methods: - activity : Computes activity from mass concentration and density.

Examples:

Example Usage

strategy = ActivityIdealVolume(density=1000.0)
a = strategy.activity(2.5)
# a -> ...

References: - "Raoult's Law," Wikipedia.

Initialize the ActivityIdealVolume strategy.

Parameters:

• - density –

  Density of the species in kg/m^3.

Source code in particula/particles/activity_strategies.py

def __init__(self, density: Union[float, NDArray[np.float64]] = 0.0):
    """Initialize the ActivityIdealVolume strategy.

    Arguments:
        - density : Density of the species in kg/m^3.
    """
    self.density = density

activity

activity(mass_concentration: Union[float, NDArray[float64]]) -> Union[float, NDArray[np.float64]]

Calculate the activity of a species based on mass concentration.

Parameters:

• - mass_concentration –

  Concentration of the species in kg/m^3.

• - density –

  Density of the species in kg/m^3.

Returns:

• Union[float, NDArray[float64]] –
  • Activity of the species, unitless.

Source code in particula/particles/activity_strategies.py

def activity(
    self, mass_concentration: Union[float, NDArray[np.float64]]
) -> Union[float, NDArray[np.float64]]:
    """Calculate the activity of a species based on mass concentration.

    Arguments:
        - mass_concentration : Concentration of the species in kg/m^3.
        - density : Density of the species in kg/m^3.

    Returns:
        - Activity of the species, unitless.
    """
    return get_ideal_activity_volume(
        mass_concentration=mass_concentration, density=self.density
    )

ActivityKappaParameter

ActivityKappaParameter(kappa: NDArray[float64] | None = None, density: NDArray[float64] | None = None, molar_mass: NDArray[float64] | None = None, water_index: int = 0)

Bases: ActivityStrategy

Non-ideal activity strategy using the kappa hygroscopic parameter.

Attributes:

• - (kappa) –

  Kappa hygroscopic parameters (array or scalar).

• - (density) –

  Densities (array or scalar) in kg/m^3.

• - (molar_mass) –

  Molar masses (array or scalar) in kg/mol.

• - (water_index) –

  Index identifying the water species in arrays.

• activity : Computes non-ideal activity using kappa hygroscopicity approach.

Examples:

Example Usage

import particula as par
import numpy as np
strategy = par.particles.ActivityKappaParameter(
    kappa=np.array([0.1, 0.0]),
    density=np.array([1000.0, 1200.0]),
    molar_mass=np.array([0.018, 0.058]),
    water_index=0,
)
a = strategy.activity(np.array([1.0, 2.0]))
# a -> ...

References

• Petters, M. D., & Kreidenweis, S. M. (2007). A single parameter representation of hygroscopic growth and cloud condensation nucleus activity. Atmospheric Chemistry and Physics, 7(8), 1961-1971. DOI.

Initialize the ActivityKappaParameter strategy.

Parameters:

• - kappa –

  Kappa hygroscopic parameters (array or scalar).

• - density –

  Densities in kg/m^3 (array or scalar).

• - molar_mass –

  Molar masses in kg/mol (array or scalar).

• - water_index –

  Index of the water species.

Source code in particula/particles/activity_strategies.py

def __init__(
    self,
    kappa: NDArray[np.float64] | None = None,
    density: NDArray[np.float64] | None = None,
    molar_mass: NDArray[np.float64] | None = None,
    water_index: int = 0,
):
    """Initialize the ActivityKappaParameter strategy.

    Arguments:
        - kappa : Kappa hygroscopic parameters (array or scalar).
        - density : Densities in kg/m^3 (array or scalar).
        - molar_mass : Molar masses in kg/mol (array or scalar).
        - water_index : Index of the water species.
    """
    self.kappa = (
        kappa if kappa is not None else np.array([0.0], dtype=np.float64)
    )
    self.density = (
        density
        if density is not None
        else np.array([0.0], dtype=np.float64)
    )
    self.molar_mass = (
        molar_mass
        if molar_mass is not None
        else np.array([0.0], dtype=np.float64)
    )
    self.water_index = water_index

activity

activity(mass_concentration: Union[float, NDArray[float64]]) -> Union[float, NDArray[np.float64]]

Calculate the activity of a species based on mass concentration.

Parameters:

• - mass_concentration –

  Concentration of the species in kg/m^3.

Returns:

• Union[float, NDArray[float64]] –
  • Activity of the species, unitless.

References

• Petters, M. D., & Kreidenweis, S. M. (2007). A single parameter representation of hygroscopic growth and cloud condensation nucleus activity. Atmospheric Chemistry and Physics, 7(8), 1961-1971. DOI.

Source code in particula/particles/activity_strategies.py

def activity(
    self, mass_concentration: Union[float, NDArray[np.float64]]
) -> Union[float, NDArray[np.float64]]:
    """Calculate the activity of a species based on mass concentration.

    Arguments:
        - mass_concentration : Concentration of the species in kg/m^3.

    Returns:
        - Activity of the species, unitless.

    References:
        - Petters, M. D., & Kreidenweis, S. M. (2007). A single parameter
          representation of hygroscopic growth and cloud condensation
          nucleus activity. Atmospheric Chemistry and Physics, 7(8),
          1961-1971. [DOI](https://doi.org/10.5194/acp-7-1961-2007).
    """
    return get_kappa_activity(
        mass_concentration=mass_concentration,
        kappa=self.kappa,
        density=self.density,
        molar_mass=self.molar_mass,
        water_index=self.water_index,
    )

ActivityStrategy

Bases: ABC

Abstract base class for vapor pressure and activity calculations.

This interface is used by subclasses for computing particle activity and partial pressures. General methods include activity() and partial_pressure().

Methods: - get_name : Return the type of the activity strategy. - activity : Calculate the activity of a species. (abstract method) - partial_pressure : Calculate the partial pressure of a species using its pure vapor pressure and computed activity.

Examples:

Example Subclass

class CustomActivity(ActivityStrategy):
    def activity(self, mass_concentration):
        return 1.0

my_activity = CustomActivity()
pvap = my_activity.partial_pressure(101325.0, 1.0)
# pvap -> 101325.0

References: - "Vapor Pressure," Wikipedia.

activity abstractmethod

activity(mass_concentration: Union[float, NDArray[float64]]) -> Union[float, NDArray[np.float64]]

Calculate the activity of a species based on its mass concentration.

Parameters:

• - mass_concentration –

  Concentration of the species in kg/m^3.

Returns:

• Union[float, NDArray[float64]] –
  • Activity of the species, unitless.

Source code in particula/particles/activity_strategies.py

@abstractmethod
def activity(
    self, mass_concentration: Union[float, NDArray[np.float64]]
) -> Union[float, NDArray[np.float64]]:
    """Calculate the activity of a species based on its mass concentration.

    Arguments:
        - mass_concentration : Concentration of the species in kg/m^3.

    Returns:
        - Activity of the species, unitless.
    """

get_name

get_name() -> str

Return the type of the activity strategy.

Source code in particula/particles/activity_strategies.py

def get_name(self) -> str:
    """Return the type of the activity strategy."""
    return self.__class__.__name__

partial_pressure

partial_pressure(pure_vapor_pressure: Union[float, NDArray[float64]], mass_concentration: Union[float, NDArray[float64]]) -> Union[float, NDArray[np.float64]]

Calculate the vapor pressure of species in the particle phase.

Parameters:

• - pure_vapor_pressure –

  Pure vapor pressure of the species in Pa.

• - mass_concentration –

  Concentration of the species in kg/m^3.

Returns:

• Union[float, NDArray[float64]] –
  • Vapor pressure of the particle in Pa.

Source code in particula/particles/activity_strategies.py

def partial_pressure(
    self,
    pure_vapor_pressure: Union[float, NDArray[np.float64]],
    mass_concentration: Union[float, NDArray[np.float64]],
) -> Union[float, NDArray[np.float64]]:
    """Calculate the vapor pressure of species in the particle phase.

    Arguments:
        - pure_vapor_pressure : Pure vapor pressure of the species in Pa.
        - mass_concentration : Concentration of the species in kg/m^3.

    Returns:
        - Vapor pressure of the particle in Pa.
    """
    return get_surface_partial_pressure(
        pure_vapor_pressure=pure_vapor_pressure,
        activity=self.activity(mass_concentration),
    )