eradiate.scenes.atmosphere.ParticleLayer#

class eradiate.scenes.atmosphere.ParticleLayer(id='atmosphere', geometry=None, scale=None, bottom=<Quantity(0.0, 'kilometer')>, top=<Quantity(1.0, 'kilometer')>, distribution='uniform', w_ref=<Quantity(550, 'nanometer')>, tau_ref=<Quantity(0.2, 'dimensionless')>, n_layers=16, dataset='spectra/particles/govaerts_2021-continental.nc')[source]#

Bases: eradiate.scenes.atmosphere._core.AbstractHeterogeneousAtmosphere

Particle layer scene element [particle_layer].

The particle layer has a vertical extension specified by a bottom altitude (set by bottom) and a top altitude (set by top). Inside the layer, the particles number is distributed according to a distribution (set by distribution). See particle_dist for the available distribution types and corresponding parameters. The particle layer is itself divided into a number of (sub-)layers (n_layers) to allow to describe the variations of the particles number with altitude. The particle density in the layer is adjusted so that the particle layer’s optical thickness at a specified reference wavelength (w_ref) meets a specified value (tau_ref). The particles radiative properties are specified by a data set (dataset).

Parameters

id (str, optional, default: "atmosphere") – User-defined object identifier.
geometry (AtmosphereGeometry or dict or str, optional, default: None) – Parameters defining the basic geometry of the atmosphere.
scale (float, optional, default: None) – If set, the extinction coefficient is scaled by the corresponding amount during computation.
bottom (float or quantity, default: 0 km) – Bottom altitude of the particle layer.

Unit-enabled field (default: ucc[length])
top (float or quantity, default: 1 km.) – Top altitude of the particle layer.

Unit-enabled field (default: ucc[length]).
distribution (ParticleDistribution or dict or {"uniform", "gaussian", "exponential"}, optional, default: "uniform") – Particle distribution. Simple defaults can be set using a string: "uniform" (resp. "gaussian", "exponential") is converted to UniformParticleDistribution() (resp. GaussianParticleDistribution(), ExponentialParticleDistribution()).
w_ref (quantity or float, default: 550.0) – Reference wavelength at which the extinction optical thickness is specified.

Unit-enabled field (default: ucc[length]).
tau_ref (quantity or float, default: 0.2) – Extinction optical thickness at the reference wavelength.

Unit-enabled field (default: ucc[dimensionless]).
n_layers (int, default: 16) – Number of layers in which the particle layer is discretised.
dataset (Dataset or path-like, optional, default: spectra/particles/govaerts_2021-continental.nc) – Particle radiative property data set. If a path is passed, the converter tries to open the corresponding file on the hard drive; if this fails, it tries to load a resource from the data store. Refer to the data guide for the format requirements of this data set.

Fields

id (str or None) – User-defined object identifier.
geometry (AtmosphereGeometry or None) – Parameters defining the basic geometry of the atmosphere.
scale (float or None) – If set, the extinction coefficient is scaled by the corresponding amount during computation.
distribution (ParticleDistribution) – Particle distribution.
w_ref (quantity) – Reference wavelength at which the extinction optical thickness is specified.
tau_ref (quantity) – Extinction optical thickness at the reference wavelength.
n_layers (int) – Number of layers in which the particle layer is discretised.
dataset (Dataset) – Particle radiative property data set.

eval_albedo(spectral_ctx)[source]#

Evaluate albedo spectrum based on a spectral context. This method dispatches evaluation to specialised methods depending on the active mode.

Parameters: spectral_ctx (SpectralContext) – A spectral context data structure containing relevant spectral parameters (e.g. wavelength in monochromatic mode, bin and quadrature point index in CKD mode).
Returns: quantity – Evaluated spectrum as an array with length equal to the number of layers.

eval_fractions()[source]#

Compute the particle number fraction in the particle layer.

Returns: ndarray – Particle fractions.

eval_mfp(ctx)[source]#

Compute a typical scattering mean free path. This rough estimate can be used e.g. to compute a distance guaranteeing that the medium can be considered optically thick.

Parameters: ctx (KernelDictContext) – A context data structure containing parameters relevant for kernel dictionary generation.
Returns: mfp (quantity) – Mean free path estimate.

eval_radprops(spectral_ctx, optional_fields=False)[source]#

Return a dataset that holds the radiative properties profile of the particle layer.

Parameters

spectral_ctx (SpectralContext) – A spectral context data structure containing relevant spectral parameters (e.g. wavelength in monochromatic mode, bin and quadrature point index in CKD mode).
optional_fields (bool, optional, default: False) – If True, extra the optional sigma_a and sigma_s fields, not required for scene construction but useful for analysis and debugging.

Returns

Dataset – Particle layer radiative properties profile dataset.

eval_shape(ctx)#

Return the shape enclosing the atmosphere’s volume.

Parameters: ctx (KernelDictContext) – A context data structure containing parameters relevant for kernel dictionary generation.
Returns: shape (CuboidShape or SphereShape) – Computed shape used as the medium stencil for kernel dictionary generation.

eval_sigma_a(spectral_ctx)[source]#

Evaluate absorption coefficient given a spectral context.

Parameters: spectral_ctx (SpectralContext) – A spectral context data structure containing relevant spectral parameters (e.g. wavelength in monochromatic mode, bin and quadrature point index in CKD mode).
Returns: quantity – Particle layer extinction coefficient.

eval_sigma_s(spectral_ctx)[source]#

Evaluate scattering coefficient given a spectral context.

Parameters: spectral_ctx (SpectralContext) – A spectral context data structure containing relevant spectral parameters (e.g. wavelength in monochromatic mode, bin and quadrature point index in CKD mode).
Returns: quantity – Particle layer scattering coefficient.

eval_sigma_t(spectral_ctx)[source]#

Evaluate extinction coefficient given a spectral context.

Parameters: spectral_ctx (SpectralContext) – A spectral context data structure containing relevant spectral parameters (e.g. wavelength in monochromatic mode, bin and quadrature point index in CKD mode).
Returns: quantity – Particle layer extinction coefficient.

kernel_dict(ctx)#

Return a dictionary suitable for kernel scene configuration.

Parameters: ctx (KernelDictContext) – A context data structure containing parameters relevant for kernel dictionary generation.
Returns: KernelDict – Kernel dictionary which can be loaded as a Mitsuba object.

kernel_media(ctx)#

Return medium plugin specifications only.

Parameters: ctx (KernelDictContext) – A context data structure containing parameters relevant for kernel dictionary generation.
Returns: kernel_dict (KernelDict) – A kernel dictionary containing all the media attached to the atmosphere.

kernel_phase(ctx)[source]#

Return phase function plugin specifications only.

Parameters: ctx (KernelDictContext) – A context data structure containing parameters relevant for kernel dictionary generation.
Returns: kernel_dict (KernelDict) – A kernel dictionary containing all the phase functions attached to the atmosphere.

kernel_shapes(ctx)#

Return shape plugin specifications only.

Parameters: ctx (KernelDictContext) – A context data structure containing parameters relevant for kernel dictionary generation.
Returns: kernel_dict (KernelDict) – A kernel dictionary containing all the shapes attached to the atmosphere.

kernel_width_plane_parallel(ctx)#

When using a plane parallel geometry, compute the size of the cuboid shape enclosing the participating medium representing the atmosphere.

Parameters: ctx (KernelDictContext) – A context data structure containing parameters relevant for kernel dictionary generation.
Returns: width (quantity) – Computed cuboid width, eval to 10 / self.eval_mfp(ctx) if ` self.geometry.width` is set to AUTO, self.geometry.width otherwise.
Raises: ValueError – When a geometry other than PlaneParallelGeometry is used.

update()[source]#: Update internal state.

property bottom#

Atmosphere bottom altitude.

Type: pint.Quantity

property height#

Atmosphere height.

Type: pint.Quantity

property id_medium#

Kernel dictionary key of the atmosphere’s medium object.

Type: str

property id_phase#

Kernel dictionary key of the atmosphere’s phase function object.

Type: str

property id_shape#

Kernel dictionary key of the atmosphere’s shape object.

Type: str

property top#

Atmosphere top altitude.

Type: pint.Quantity

property z_layer#

Compute the layer altitude mesh within the particle layer.

The layer altitude mesh corresponds to a regular level altitude mesh from the layer’s bottom altitude to the layer’s top altitude with a number of points specified by n_layer.

Returns: quantity – Layer altitude mesh.

property z_level#

Compute the level altitude mesh within the particle layer.

The level altitude mesh corresponds to a regular level altitude mesh from the layer’s bottom altitude to the layer’s top altitude with a number of points specified by n_layer + 1.

Returns: quantity – Level altitude mesh.