eradiate.scenes.atmosphere.ParticleLayer#

class eradiate.scenes.atmosphere.ParticleLayer(id='atmosphere', geometry='plane_parallel', 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')>, dataset='govaerts_2021-continental', has_absorption=True, has_scattering=True)[source]#

Bases: 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") – Identifier of the current scene element.
geometry (SceneGeometry or dict or str, optional, default: "plane_parallel") – Parameters defining the basic geometry of the scene.
scale (float, optional) – 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[‘wavelength’]).
tau_ref (quantity or float, default: 0.2) – Extinction optical thickness at the reference wavelength.

Unit-enabled field (default: ucc[dimensionless]).
dataset (Dataset or path-like or str, optional, default: govaerts_2021-continental) – Particle radiative property data set.If an xarray dataset is passed, the dataset is used as is (refer to the data guide for the format requirements of this dataset).If a path is passed, the converter tries to open the corresponding file on the hard drive; should that fail, it queries the Eradiate datastore with that path.If a string is passed, it is interpreted as an identifier for a particle radiative property dataset in the Eradiate data store.
has_absorption (bool, default: True) – Absorption bypass switch. If True, the absorption coefficient is computed. Else, the absorption coefficient is not computed and instead set to zero.
has_scattering (bool, default: True) – Scattering bypass switch. If True, the scattering coefficient is computed. Else, the scattering coefficient is not computed and instead set to zero.

Fields:

id (str or None) – Identifier of the current scene element.
geometry (SceneGeometry) – Parameters defining the basic geometry of the scene.
scale (float or None) – If set, the extinction coefficient is scaled by the corresponding amount during computation.
bottom (quantity) – Bottom altitude of the particle layer.
top (quantity) – Top altitude of the particle layer.
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.
dataset (Dataset) – Particle radiative property data set.If an xarray dataset is passed, the dataset is used as is (refer to the data guide for the format requirements of this dataset).If a path is passed, the converter tries to open the corresponding file on the hard drive; should that fail, it queries the Eradiate datastore with that path.If a string is passed, it is interpreted as an identifier for a particle radiative property dataset in the Eradiate data store.
has_absorption (bool) – Absorption bypass switch.
has_scattering (bool) – Scattering bypass switch.

eval_albedo(sctx, zgrid=None)[source]#

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

Parameters:

sctx (SpectralContext) – A spectral context data structure containing relevant spectral parameters (e.g. wavelength in monochromatic mode, bin and quadrature point index in CKD mode).
zgrid (ZGrid, optional) – Altitude grid on which evaluation is performed. If unset, an instance-specific default is used (see zgrid).

Returns:

quantity – Evaluated spectrum as an array with length equal to the number of layers.

eval_fractions(zgrid)[source]#

Compute the particle number fraction in the particle layer.

Returns:: ndarray – Particle number fractions as a (n_layers,)-shaped array.

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(sctx, zgrid=None, optional_fields=False)#

Evaluate the extinction coefficients and albedo profiles.

Parameters:

sctx (SpectralContext) – A spectral context data structure containing relevant spectral parameters (e.g. wavelength in monochromatic mode, bin and quadrature point index in CKD mode).
zgrid (ZGrid, optional) – Altitude grid on which evaluation is performed. If unset, an instance-specific default is used (see zgrid).
optional_fields (bool, optional, default: False) – If True, also output the absorption and scattering coefficients, not required for scene setup but useful for analysis and debugging.

Returns:

Dataset – A dataset with the following variables:

sigma_t: extinction coefficient;
albedo: albedo;
sigma_a: absorption coefficient (optional);
sigma_s: scattering coefficient (optional).

and coordinates:

z: altitude.

eval_sigma_a(sctx, zgrid=None)[source]#

Evaluate absorption coefficient given a spectral context.

Parameters:

sctx (SpectralContext) – A spectral context data structure containing relevant spectral parameters (e.g. wavelength in monochromatic mode, bin and quadrature point index in CKD mode).
zgrid (ZGrid, optional) – Altitude grid on which evaluation is performed. If unset, an instance-specific default is used (see zgrid).

Returns:

quantity – Particle layer extinction coefficient.

eval_sigma_s(sctx, zgrid=None)[source]#

Evaluate scattering coefficient given a spectral context.

Parameters:

sctx (SpectralContext) – A spectral context data structure containing relevant spectral parameters (e.g. wavelength in monochromatic mode, bin and quadrature point index in CKD mode).
zgrid (ZGrid, optional) – Altitude grid on which evaluation is performed. If unset, an instance-specific default is used (see zgrid).

Returns:

quantity – Particle layer scattering coefficient.

eval_sigma_t(sctx, zgrid=None)[source]#

Evaluate extinction coefficient given a spectral context.

Parameters:

sctx (SpectralContext) – A spectral context data structure containing relevant spectral parameters (e.g. wavelength in monochromatic mode, bin and quadrature point index in CKD mode).
zgrid (ZGrid, optional) – Altitude grid on which evaluation is performed. If unset, an instance-specific default is used (see zgrid).

Returns:

quantity – Particle layer extinction coefficient.

traverse(callback)#

Traverse this scene element and collect kernel dictionary template and parameter update map contributions.

Parameters:: callback (SceneTraversal) – Callback data structure storing the collected data.

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

property bottom_altitude#

Returns:: quantity – Atmosphere bottom altitude.

property height#

Returns:: quantity – Atmosphere height.

property medium_id#

Returns:: str – ID of the medium associated with the atmosphere in the Mitsuba scene tree.

property objects#

Map of child objects associated with this scene element.

Returns:: dict – A dictionary mapping object names to a corresponding object to be inserted in the Eradiate scene graph.

property params#

Returns:: dict[str, UpdateParameter] or None – A dictionary mapping parameter paths, consisting of dot-separated strings, to a corresponding update protocol.