[Model]

This header defines the type of forward model (FM) that will be computed by TauREx3. There are several built-in forward model_type values:

  • transmission

    • Transmission forward model

  • emission

    • Emission forward model

  • directimage

    • Direct-image forward model

  • multi_transit

    • Composite transmission model combining multiple 1D regions

  • multi_eclipse

    • Composite emission model combining multiple 1D regions

  • multi_directimage

    • Composite direct-imaging model combining multiple 1D regions

  • custom

Both emission and direct image also include an optional keyword ngauss which dictates the number of Gaussian quadrate points used in the integration. By default this is set to ngauss=4.

Composite Forward Models

TauREx also includes built-in composite forward models for stitching together multiple 1D atmospheric regions into a single weighted spectrum. These were previously distributed through the taurex-multimodel plugin and are now available directly in the main package.

The parameter-file-driven entry points are:

model_type

Description

multi_transit

Weighted combination of multiple transmission regions

multi_eclipse

Weighted combination of multiple emission regions

multi_directimage

Weighted combination of multiple direct-image regions

Each region is defined through a separate parameter file listed in parfiles. TauREx reads the temperature, chemistry, pressure, and contribution sections from each file and combines the resulting spectra with the optional fractions list. For retrievals, provide N-1 fractions rather than N if you want TauREx to adapt the last region automatically. In that case the final fraction is inferred from the remaining weight so that the total remains unity. For a complete worked setup, see the multimodel notebook example in Notebook Examples.

Example composite transmission setup:

[Model]
model_type = multi_transit
parfiles = day.par, night.par
fractions = 0.7

The same pattern applies to multi_eclipse and multi_directimage.

Two internal helper models are also exposed for advanced use:

  • emission_radscale or eclipse_radscale for radius-scaled emission regions.

  • direct_radscale or directimage_radscale for radius-scaled direct-image regions.

Contributions

Contributions define what processes in the atmosphere contribute to the optical depth. These contributions are defined as subheaders with the name of the header being the contribution to add into the forward model.Any forward model type can be augmented with these contributions.

Examples

Transmission spectrum with molecular absorption and CIA from H2-He and H2-H2:

[Model]
model_type = transmission
    [[Absorption]]

    [[CIA]]
    cia_pairs = H2-He,He-He

Emission spectrum with molecular absorption, CIA and Rayleigh scattering:

[Model]
model_type = emission
ngauss = 4
    [[Absorption]]

    [[CIA]]
    cia_pairs = H2-He,He-He

    [[Rayleigh]]

The following sections give a list of available contributions

Molecular Absorption

[[Absorption]]

Adds molecular absorption to the forward model. Here the active molecules contribute to absorption. No other keywords are needed. No fitting parameters.

Collisionally Induced Absorption

[[CIA]]

Adds collisionally induced absorption to the forward model. Requires cia_path to be set. Both active and inactive molecules can contribute. No fitting parameters

Keywords

Variable

Type

Description

cia_pairs

list

List of molecular pairs. e.g. H2-He, H2-H2

Rayleigh Scattering

[[Rayleigh]]

Adds Rayleigh scattering to the forward model. Both active and inactive molecules can contribute. No keywords or fitting parameters.

Optically thick clouds

[[SimpleClouds]] or [[ThickClouds]]

A simple cloud model that puts a infinitely absorping cloud deck in the atmosphere.

Keywords

Variable

Type

Description

clouds_pressure

float

Pressure of top of cloud-deck in Pa

Fitting Parameters

Variable

Type

Description

clouds_pressure

float

Pressure of top of cloud-deck in Pa

Mie scattering (Lee)

[[LeeMie]]

Computes Mie scattering contribution to optical depth Formalism taken from: Lee et al. 2013, ApJ, 778, 97

Keywords

Variable

Type

Description

lee_mie_radius

float

Particle radius in um

lee_mie_q

float

Extinction coefficient

lee_mie_mix_ratio

float

Mixing ratio in atmosphere

lee_mie_bottomP

float

Bottom of cloud deck in Pa

lee_mie_topP

float

Top of cloud deck in Pa

Fitting Parameters

Parameter

Type

Description

lee_mie_radius

float

Particle radius in um

lee_mie_q

float

Extinction coefficient

lee_mie_mix_ratio

float

Mixing ratio in atmosphere

lee_mie_bottomP

float

Bottom of cloud deck in Pa

lee_mie_topP

float

Top of cloud deck in Pa

Mie scattering (BH)

[[BHMie]]

Computes a Mie scattering contribution using method given by Bohren & Huffman 2007

Keywords

Variable

Type

Description

bh_particle_radius

float

Particle radius in um

bh_cloud_mix

float

Mixing ratio in atmosphere

bh_clouds_bottomP

float

Bottom of cloud deck in Pa

bh_clouds_topP

float

Top of cloud deck in Pa

mie_path

str

Path to molecule scattering parameters

mie_type

cloud or haze

Type of mie cloud

Fitting Parameters

Parameter

Type

Description

bh_particle_radius

float

Particle radius in um

bh_cloud_mix

float

Mixing ratio in atmosphere

bh_clouds_bottomP

float

Bottom of cloud deck in Pa

bh_clouds_topP

float

Top of cloud deck in Pa

Mie scattering (Flat)

[[FlatMie]]

Computes a flat absorbing region of the atmosphere across all wavelengths

Keywords

Variable

Type

Description

flat_mix_ratio

float

Opacity value

flat_bottomP

float

Bottom of absorbing region in Pa

flat_topP

float

Top of absorbing region in Pa

Fitting Parameters

Parameter

Type

Description

flat_mix_ratio

float

Opacity value

flat_bottomP

float

Bottom of absorbing region in Pa

flat_topP

float

Top of absorbing region in Pa