pyrcel.aerosol.AerosolSpecies

class pyrcel.aerosol.AerosolSpecies(species, distribution, kappa, rho=None, mw=None, bins=None, r_min=None, r_max=None)

Container class for organizing aerosol metadata.

To allow flexibility with how aerosols are defined in the model, this class is meant to act as a wrapper to contain metadata about aerosols (their species name, etc), their chemical composition (particle mass, hygroscopicity, etc), and the particular size distribution chosen for the initial dry aerosol. Because the latter could be very diverse - for instance, it might be desired to have a monodisperse aerosol population, or a bin representation of a canonical size distribution - the core of this class is designed to take those representations and homogenize them for use in the model.

To construct an AerosolSpecies, only the metadata (species and kappa) and the size distribution needs to be specified. The size distribution (distribution) can be an instance of Lognorm, as long as an extra parameter bins, which is an integer representing how many bins into which the distribution should be divided, is also passed to the constructor. In this case, the constructor will figure out how to slice the size distribution to calculate all the aerosol dry radii and their number concentrations. If r_min and r_max are supplied, then the size range of the aerosols will be bracketed; else, the supplied distribution will contain a shape parameter or other bounds to use.

Alternatively, a dict can be passed as distribution where that slicing has already occurred. In this case, distribution must have 2 keys: r_drys and Nis. Each of the values stored to those keys should fit the attribute descriptors above (although they don’t need to be arrays - they can be any iterable.)

Parameters:

species : string

Name of aerosol species.

distribution : { LogNorm, MultiLogNorm, dict }

Representation of aerosol size distribution.

kappa : float

Hygroscopicity of species.

rho : float, optional

Density of dry aerosol material, kg m**-3.

mw : float, optional

Molecular weight of dry aerosol material, kg/mol.

bins : int

Number of bins in discretized size distribution.

Examples

Constructing sulfate aerosol with a specified lognormal distribution -

>>> aerosol1 = AerosolSpecies('(NH4)2SO4', Lognorm(mu=0.05, sigma=2.0, N=300.),
...                           bins=200, kappa=0.6)

Constructing a monodisperse sodium chloride distribution -

>>> aerosol2 = AerosolSpecies('NaCl', {'r_drys': [0.25, ], 'Nis': [1000.0, ]},
...                          kappa=0.2)

Warning

Throws a ValueError if an unknown type of distribution is passed to the constructor, or if bins isn’t present when distribution is an instance of Lognorm.

Attributes:

nr : float

Number of sizes tracked for this aerosol.

r_drys : array of floats of length nr

Dry radii of each representative size tracked for this aerosol, m.

rs : array of floats of length nr + 1

Edges of bins in discretized aerosol distribution representation, m.

Nis : array of floats of length nr

Number concentration of aerosol of each representative size, m**-3.

total_N : float

Total number concentration of aerosol in this species, cm**-3.

__init__(species, distribution, kappa, rho=None, mw=None, bins=None, r_min=None, r_max=None)

x.__init__(…) initializes x; see help(type(x)) for signature

stats()

Compute useful statistics about this aerosol’s size distribution.

Returns:

dict

Inherits the values from the distribution, and if rho was provided, adds some statistics about the mass and mass-weighted properties.

Raises:

ValueError

If the stored distribution does not implement a stats() function.