Mie scatteringΒΆ

By default, PLATON uses a parametric model to account for scattering, with an amplitude and a slope. However, PLATON also has the ability to compute Mie scattering in place of the parametric model.

To use Mie scattering, follow Quick start to see how to do forward models and retrievals using the default parametric model. To use Mie scattering instead:

calculator.compute_depths(Rs, Mp, Rp, T,
    ri = 1.33-0.1j, frac_scale_height = 0.5, number_density = 1e9,
    part_size = 1e-6, cloudtop_pressure=1e5)

This computes Mie scattering for particles with complex refractive index 1.33-0.1j. The particles follow a lognormal size distribution with a mean radius of 1 micron and standard deviation of 0.5. They have a density of \(10^9/m^3\) at the cloud-top pressure of \(10^5\) Pa, declining with altitude with a scale height of 0.5 times the gas scale height.

To retrieve Mie scattering parameters, make sure to set log_scatt_factor to -np.inf, log_number_density to a finite value, and ri to the complex refractive index of the scattering particles (which cannot be a free parameter):

fit_info = retriever.get_default_fit_info(Rs, Mp, Rp, T,
    log_scatt_factor = -np.inf, log_number_density = 9, ri = 1.33-0.1j)

fit_info.add_uniform_fit_param('log_number_density', 5, 15)
fit_info.add_uniform_fit_param('log_part_size', -7, -4)