skyscapes.physical_model.cached

skyscapes.physical_model.cached#

Pre-computed reflectivity physical model.

Holds a fixed (K, n_nu) plane-parallel-reflectivity array that was produced by running some other AbstractPhysicalModel’s heavy radiative transfer once. contrast becomes a cubic interpolation + Lambert phase + (Rp/d)^2 lookup – microseconds per call vs. seconds for an ExoJAX 2-stream RT.

Use cases:

  • Coronagraphoto simulations where the physics is fixed across many evaluations (orbits, wavelengths, time samples).

  • ETC studies where you want fast forward-modeling against a canonical Earth-like atmosphere.

Not for HMC retrievals where parameters vary – the underlying expensive model is the right tool there.

The cache file format is a NumPy .npz with two keyword arrays (reflectivity, nu_grid) and a small JSON-style header tag for version-tracking.

Attributes#

CACHE_FORMAT_VERSION

Classes#

PrecomputedPhysicalModel

Physical model whose reflectivity spectrum has been pre-computed.

Module Contents#

skyscapes.physical_model.cached.CACHE_FORMAT_VERSION = 2#
class skyscapes.physical_model.cached.PrecomputedPhysicalModel[source]#

Bases: skyscapes.physical_model.base.AbstractPhysicalModel

Physical model whose reflectivity spectrum has been pre-computed.

Attributes:
reflectivity: Per-planet plane-parallel reflectivity R(nu)

on the wavenumber grid, shape (K, n_nu). Already includes all the physics of the original physical model (absorption, Rayleigh, clouds, surface).

nu_grid: Wavenumber grid [cm^-1], shape (n_nu,). n_nu: Length of nu_grid (static for JIT).

reflectivity: jaxtyping.Array#
nu_grid: jaxtyping.Array#
n_nu: int#
classmethod from_physical_model(model)[source]#

Pre-compute the reflectivity from an existing physical model.

Calls the model’s internal _reflectivity_all_planets once and packages the result. Requires the model to expose _reflectivity_all_planets, nu_grid, and n_nu – presently ExoJaxPhysicalModel is the supported source.

Parameters:

model (skyscapes.physical_model.base.AbstractPhysicalModel)

Return type:

PrecomputedPhysicalModel

classmethod load(path)[source]#

Load a previously-saved cache file.

Args:

path: Path to a .npz file produced by save().

Returns:

A PrecomputedPhysicalModel ready to evaluate.

Raises:
ValueError: if the file’s cache_format_version differs

from the current code’s version (would silently produce wrong spectra otherwise).

Parameters:

path (str | pathlib.Path)

Return type:

PrecomputedPhysicalModel

save(path)[source]#

Save the cached reflectivity to a .npz file.

Idempotent and safe to call from JAX-traced contexts (the save itself is plain NumPy – callers should not call this inside a JIT region, but the data is just regular arrays).

Parameters:

path (str | pathlib.Path)

Return type:

None

contrast(phase_angle_rad, dist_AU, wavelength_nm, Rp_Rearth)[source]#

Per-planet, per-time geometric-albedo contrast at one wavelength.

Args:

phase_angle_rad: Star-planet-observer phase angle, shape (K, T). dist_AU: Star-planet distance [AU], shape (K, T). wavelength_nm: Scalar wavelength [nm]. Rp_Rearth: Planet radius [Earth radii], shape (K,).

Returns:

Contrast = A_g(lambda) * Lambert_phase(beta) * (Rp/d)^2, shape (K, T). The cached array stores the underlying model’s plane-parallel (spherical) reflectivity; we convert to geometric albedo via the Lambertian-sphere factor 2/3 (Seager 2010, eq 3.36) at call time – same convention as ExoJaxPhysicalModel.contrast.

Parameters:

  • phase_angle_rad (jaxtyping.Array)

  • dist_AU (jaxtyping.Array)

  • wavelength_nm (jaxtyping.Array)

  • Rp_Rearth (jaxtyping.Array)

Return type:

jaxtyping.Array

contrast_cube(phase_angle_rad, dist_AU, wavelengths_nm, Rp_Rearth)[source]#

Per-planet, per-time geometric-albedo contrast across wavelengths.

Returns shape (W, K, T). Avoids per-wavelength recomputation by vectorising the interpolation; applies the Lambertian-sphere spherical-to-geometric conversion the same way as contrast().

Parameters:

  • phase_angle_rad (jaxtyping.Array)

  • dist_AU (jaxtyping.Array)

  • wavelengths_nm (jaxtyping.Array)

  • Rp_Rearth (jaxtyping.Array)

Return type:

jaxtyping.Array

__repr__()[source]#

Compact summary of the cached spectrum.

Return type:

str