taurex-pcq 1.0

A TauREx plugin implementing Pre Computed Qext grids for cloud models

Faster clouds for TauREx 3

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This plugin provides a new nethod to inclue aerosols in TauREx 3, extending the TauREx-PyMieScatt plugin. It significantly speeds up the cloud models by using precomputed extinction efficiency (Q_ext) grids. TauREx-PCQ also considerably improves the computation scaling with the number of clouds in the models. The speed-ups for single cloud retrievals are betwwen 1.4 and 2.7. Although, a single-cloud retrieval using Qext grids achieved a speed-up of 1.4, the same retrieval with four clouds became 17 times faster than the corresponding retrieval using direct Mie calculations. The grids details and validation can be found in Voyer & Changeat (2026), if you use TauREx-PCQ or the grids please cite this paper. The species already available are Mg2SiO4, MgSiO3 (amorph sol-gel and amorph glass), SiO2 (alpha and amorph), SiO, the Titan tholins and water ice. They can be found at: 10.5281/zenodo.17456673 .

For any inquiries, please contact: [e-mail]

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🔧 Features

• ✅ Compatible with transit and emmsion models.

• ✅ Works with any aerosol specie given that the user provides a .h5 file with :

• A radius_grid dataset with the particule sizes in microns ( length a ).

• A wavenumber_grid dataset with the wavenumber at which the Q_ext were computed in cm-1 ( length b )

• A Qext_grid dataset with the computed Q_ext from PyMieScat ( length (a, b) )

As an extension of TauREx-PyMieScatt, this pulgin includes the same capabilities

• ✅ Supports multiple particle size distributions:
  • normal (log-normal)
  • budaj (2015)
  • deirmendjian (1964)
• ✅ Multiple species and per-species fitting
• ✅ Particle decay with altitude (exp_decay based on Whitten 2008 / Atreya 2005)
• ✅ Computes exctinction using the species optical constant via Effective Medium Theory (Bohren & Huffman 1983)
• ✅ Multiple fittable parameters for TauREx retrievals

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🔧 Model Parameters

Name	Description
species	Your name for the species included through the mie_species_path parameter. This name will be used as suffixes added to the other parameters to distinguish between included species.
mie_species_path	Paths to the Q_ext grids of the aerosols you want to include
mie_particle_radius_distribution	"normal", "budaj", or "deirmendjian"
mie_particle_mean_radius	Mean particle radius (µm)
mie_particle_logstd_radius	Log-normal std dev (for "normal" distribution)
mie_particle_paramA/B/C/D	Parameters for Deirmendjian distribution
mie_particle_mix_ratio	Number density (molecules/m³)
mie_midP	Pressure at cloud center (Pa)
mie_rangeP	Extend of the clouds in log scale around mie_midP. If mie_midP = 1e5 Pa and mie_rangeP = 1 then clouds extend from 1e6 to 1e4 Pa
mie_particle_altitude_distrib	Currently supports 'exp_decay' or 'linear'
mie_particle_altitude_decay	Decay exponent per species e.g -5

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💡 Usage Example in a TauREx parameter file or 'parfile'

[Model]
model_type = transit

    [[PyMieScattGridExtinction]]

    species = SiO, Mg2SiO4_glass, custom_molecule
    mie_species_path = path_to_SiO.h5 , path_to_Mg2SiO4_glass.h5 , path_to_custom_molecule.h5   #e.g. You can use the optical constant from Kitzmann and Heng 2018
    mie_particle_radius_distribution = budaj
    mie_particle_mean_radius = 0.1, 0.4 , 10
    mie_midP = 1e5, 1e2, 1
    mie_rangeP = 3 , 1 , 2
    mie_particle_mix_ratio = 1e5, 1e8 , 10e3
    mie_particle_radius_Nsampling = 5
    mie_particle_altitude_distrib = linear

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Limitations

As the Q_ext are computed for a range of radii between 1 nm and 30 microns, it is strongly recomended that the mie_particle_mean_radius prior does not extend beyond this range. Any radius outside of the range will use the Q_ext of the closest radius present in the grid.