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Constituents

Constituents#

class sasktran2.constituent.Rayleigh(method: str = 'bates', method_kwargs: dict | None = None)[source]#

Bases: Constituent

An implementation of Rayleigh scattering. Cross sections (and depolarization factors) can be calculated multiple ways, with the default method being that of ‘bates’.

Rayleigh scattering number density is estimated through the ideal gas law.

This Constituent requires that the atmosphere object have temperature_k, pressure_pa, and wavelength_nm are all defined inside the sasktran2.Atmosphere object.

Parameters:

  • method (str, optional) – Method to use to calculate the cross section. Supported methods are [‘bates’], by default ‘bates’

  • method_kwargs (dict, optional) – kwargs that can be passed to the method

Raises:

ValueError – If input method is not supported

class sasktran2.constituent.VMRAltitudeAbsorber(optical_property: OpticalProperty, altitudes_m: array, vmr: array, out_of_bounds_mode: str = 'zero')[source]#

Bases: Constituent

An atmospheric constituent that is specified through volume mixing ratio (VMR) on an altitude grid. The altitude grid need not match the global atmospheric grid, in the case they are different the VMRs will be linearly interpolated to the atmospheric grid locations.

The constituent has an associated OpticalProperty that defines the absorption cross section as a function of wavelength.

Parameters:

  • optical_property (OpticalProperty) – An object that provides absorption cross sections as a function of wavelength

  • altitudes_m (np.array) – Altitudes in [m] that the VMR is specified on

  • vmr (np.array) – Volume mixing ratio

  • out_of_bounds_mode (str, optional) – One of [‘zero’, ‘extend’], ‘zero’ will set the VMR to be 0 on any altitudes that are out of bounds. ‘extend’ will extend the last or first VMR value. By default ‘zero’

class sasktran2.constituent.NumberDensityScatterer(optical_property: OpticalProperty, altitudes_m: array, number_density: array, out_of_bounds_mode: str = 'zero', **kwargs)[source]#

Bases: Constituent

A scattering constituent that is defined by a number density on an altitude grid and an optical property

Parameters:

  • optical_property (OpticalProperty) – The optical property defining the scattering information

  • altitudes_m (np.array) – The altitude grid in [m]

  • number_density (np.array) – Number density in [m^-3]

  • out_of_bounds_mode (str, optional) – Interpolation mode outside of the boundaries, “extend” and “zero” are supported, by default “zero”

  • kwargs (dict) – Additional arguments to pass to the optical property.

class sasktran2.constituent.ExtinctionScatterer(optical_property: OpticalProperty, altitudes_m: array, extinction_per_m: array, extinction_wavelength_nm: float, out_of_bounds_mode: str = 'zero', **kwargs)[source]#

Bases: NumberDensityScatterer

A scattering constituent that is defined by a number density on an altitude grid and an optical property

Parameters:

  • optical_property (OpticalProperty) – The optical property defining the scattering information

  • altitudes_m (np.array) – The altitude grid in [m]

  • extinction_per_m (np.array) – Extinction in [m^-1]

  • extinction_wavelength_nm (float) – Wavelength that the extinction profile is specified at

  • out_of_bounds_mode (str, optional) – Interpolation mode outside of the boundaries, “extend” and “zero” are supported, by default “zero”

  • kwargs (dict) – Additional arguments passed to the optical property

class sasktran2.constituent.CollisionInducedAbsorber(optical_property: OpticalProperty, name: str)[source]#

Bases: Constituent

An implementation of collision-induced absorption for quantities with known constant mole fractions.

Air number density is estimated through the ideal gas law. Currently the mole fraction is applied to the air number density, though in the future it should be applied to dry air only.

This Constituent requires that the atmosphere object have temperature_k, pressure_pa, and wavelength_nm all defined inside the sasktran2.Atmosphere object.

Parameters:

  • optical_property (OpticalProperty) – Optical property that computes the collision-induced cross section in [m^5].

  • name (str) – Molecule names to load mole fractions. Currently supported: O2O2

Surfaces#

class sasktran2.constituent.LambertianSurface(albedo: array, wavelengths_nm: array = None, wavenumbers_cminv: array = None, out_of_bounds_mode='zero')[source]#

Bases: Constituent

A Lambertian surface that is defined by albedo at discrete grid points.

This can either operate in a “scalar” mode where the albedo is constant in wavelength, a “native” mode where the albedo is defined on the same grid as the atmosphere, or an “interpolated” mode where the albedo is interpolated either in wavenumber or wavelength

Parameters:

  • albedo (np.array) – Surface albedo. Can be a scalar to indicate it is constant in wavelength. If set to an array it must either match the atmosphere wavelength grid dimension, or one of wavelengths_nm or wavenumbers_cminv must be set.

  • wavelengths_nm (np.array, optional) – Wavelengths in [nm] that the albedo is specified at, by default None

  • wavenumbers_cminv (np.array, optional) – Wavenumbers in inverse cm that the albedo is specified at, by default None

  • out_of_bounds_mode (str, optional) – One of [“extend” or “zero”], “extend” will extend the last/first value if we are interpolating outside the grid. “zero” will set the albedo to 0 outside of the grid boundaries, by default “zero”

Dummy Constituents#

class sasktran2.constituent.AirMassFactor[source]#

Bases: Constituent

A dummy atmospheric constituent that does not add any terms to the atmosphere, but rather enables the calculation of Air Mass Factor derivatives.

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