1 rayleigh

rayleigh

1.1 Classes

Name	Description
RayleighCorrection	Block processor for applying Rayleigh scattering correction.

1.1.1 RayleighCorrection

rayleigh.RayleighCorrection(
    srf=None,
    version='polymer_legacy',
    pressure_kind='sea_level_pressure',
    sun_glint_corr=True,
    transmittance_corr=False,
    dtype='float32',
    **cfg,
)

Block processor for applying Rayleigh scattering correction.

This processor applies atmospheric Rayleigh scattering correction to satellite reflectance data using pre-computed lookup tables (LUTs).

1.1.1.1 Parameters

Name	Type	Description	Default
srf	xr.Dataset \| None	Sensor spectral response function for multi-wavelength correction.	`None`
version	Literal['polymer_legacy']	Version of the Rayleigh LUT to use. Currently only “polymer_legacy” is supported.	`"polymer_legacy"`
pressure_kind	Literal['surface_pressure', 'sea_level_pressure']	Type of pressure data to use. “sea_level_pressure” uses sea-level pressure, “surface_pressure” uses surface pressure.	`"sea_level_pressure"`
sun_glint_corr	bool	Whether to include sun glint correction. If True, subtracts Rayleigh + glint reflectance (`rho_rg`); otherwise subtracts Rayleigh reflectance only (`rho_r`).	`True`
transmittance_corr	bool	Whether to apply the Rayleigh diffuse transmittance correction. If True, the corrected reflectance `rho_rc` is divided by the total diffuse transmittance `t_d` (downward x upward), effectively compensating for remaining Rayleigh and gaseous attenuation along both the solar and sensor view paths.	`False`

1.1.1.2 Attributes

Name	Type	Description
rayleigh_lut	xr.Dataset	Pre-computed Rayleigh scattering lookup table.
interpolator	Interpolator	Interpolator object for performing multi-dimensional interpolation.
pressure_kind	str	Type of pressure data used.

1.1.1.3 Methods

Name	Description
check	Check that srf bands are identical to ds.bands

1.1.1.3.1 check

rayleigh.RayleighCorrection.check(ds)

Check that srf bands are identical to ds.bands

1.2 Functions

Name	Description
calc_odr	Calculates ODR (Optical Depth Rayleigh)
load_rayleigh_lut	Load the Rayleigh LUT (PP or SP)
main	Command-line interface for Rayleigh correction processing.
process_rayleigh	Run the full Rayleigh correction pipeline on a Level-1 product and write the result to disk.
process_rayleigh_dataset	Apply the full Rayleigh correction pipeline to a Level-1 dataset.
rayleigh_correction	Apply Rayleigh correction to `ds`

1.2.1 calc_odr

rayleigh.calc_odr(ds, srf=None)

Calculates ODR (Optical Depth Rayleigh)

Computes the Rayleigh optical depth based on altitude and pressure.

1.2.1.1 Parameters

Name	Type	Description	Default
ds	xr.Dataset	Input dataset containing altitude and pressure information. Must contain either: - “altitude” and “surface_pressure” or “sea_level_pressure” - “cwav” (central wavelength) for single-wavelength calculation	required
srf	xr.Dataset \| None	Sensor spectral response function for multi-wavelength calculation. If provided, ODR is calculated by integrating the Rayleigh cross-section over the SRF.	`None`

1.2.1.2 Returns

Name	Type	Description
	xr.DataArray	Rayleigh optical depth values with same dimensions as input.

1.2.1.3 Notes

If srf is provided, ODR is computed by integrating the Rayleigh cross-section over the SRF using the Bodhaine et al. (1999) method.
If srf is None, ODR is computed using the central wavelength from “cwav”

1.2.2 load_rayleigh_lut

rayleigh.load_rayleigh_lut(lut_rayleigh_pp, lut_rayleigh_sp, rayleigh, **kwargs)

Load the Rayleigh LUT (PP or SP)

Relative azimuth angle convention: standard (raa = saa - vaa)

Returns a dataset with: - reflectance_glitter (reflectance with a rough sea surface, no atmosphere) - reflectance_toa (including glitter) - T_tot_down: total transmission (downward) - T_tot_up: total transmission (upward)

1.2.3 main

rayleigh.main()

Command-line interface for Rayleigh correction processing.

1.2.4 process_rayleigh

rayleigh.process_rayleigh(
    input_product,
    reader,
    output_product,
    dem='eotools.dem.GTOPO30',
    transmittance_corr=True,
    **cfg,
)

Run the full Rayleigh correction pipeline on a Level-1 product and write the result to disk.

Loads the input product using the specified reader class, applies the Rayleigh correction via :func:process_rayleigh_dataset, and saves the result as a NetCDF file.

1.2.4.1 Parameters

Name	Type	Description	Default
input_product	Path	Path to the Level-1 input product.	required
reader	str	Dotted path of the reader class to use (e.g. `eoread.planetscope.Level1_Planetscope`). The class must be callable with a path and return an `xr.Dataset`.	required
output_product	Path	Destination path for the output NetCDF file.	required
dem	str	Dotted path of the DEM class to use (e.g. ‘eotools.dem.GTOPO30’ or ‘eotools.dem.CopernicusDEM’). Default is ‘eotools.dem.GTOPO30’.	`'eotools.dem.GTOPO30'`
transmittance_corr	bool	Whether to apply the Rayleigh diffuse transmittance correction to the Rayleigh-corrected reflectance. If `True`, `rho_rc` is divided by the total (downward x upward) Rayleigh diffuse transmittance `t_d`, which accounts for both direct and diffuse Rayleigh attenuation along the solar and sensor view paths. Default is `True`.	`True`

1.2.5 process_rayleigh_dataset

rayleigh.process_rayleigh_dataset(
    input_dataset,
    dem='eotools.dem.CopernicusDEM',
    transmittance_corr=True,
)

Apply the full Rayleigh correction pipeline to a Level-1 dataset.

Runs TOA reflectance initialisation, geometry, altitude, NASA ancillary data, gaseous absorption, and Rayleigh scattering correction in sequence.

1.2.5.1 Parameters

Name	Type	Description	Default
input_dataset	xr.Dataset	Level-1 dataset as returned by a reader module.	required
dem	str	Dotted path of the DEM class to use (e.g. `'eotools.dem.GTOPO30'` or `'eotools.dem.CopernicusDEM'`). Default is `'eotools.dem.GTOPO30'`.	`'eotools.dem.CopernicusDEM'`
transmittance_corr	bool	Whether to apply the Rayleigh diffuse transmittance correction to the Rayleigh-corrected reflectance. If `True`, `rho_rc` is divided by the total (downward x upward) Rayleigh diffuse transmittance `t_d`, which accounts for both direct and diffuse Rayleigh attenuation along the solar and sensor view paths. Default is `True`.	`True`

1.2.5.2 Returns

Name	Type	Description
	xr.Dataset	Rayleigh-corrected dataset containing the following variables: - `rho_gc` : Gaseous corrected reflectances - `rho_r` : Rayleigh reflectance - `rho_rg` : Rayleigh + glint reflectance - `t_d` : Diffuse transmittance (upward + downward) - `rho_rc` : Rayleigh-corrected reflectance Other input and ancillary variables: - `Rtoa` : Top-of-atmosphere reflectance - `cwav` : Central wavelengths (nm) - `altitude` : Surface altitude (m) - `horizontal_wind` : Horizontal wind speed - `sea_level_pressure` : Sea level pressure - `total_column_ozone` : Total column ozone - `total_column_water_vapour` : Total column water vapour

1.2.6 rayleigh_correction

rayleigh.rayleigh_correction(ds, srf=None, **cfg)

Apply Rayleigh correction to ds

This function applies atmospheric Rayleigh scattering correction to the top-of-atmosphere reflectance data. It computes the Rayleigh-corrected reflectance and related atmospheric transmission parameters.

This creates the following variables in ds:

Variable	Description
rho_rc	Rayleigh-corrected signal
rho_mol_gli	Rayleigh + glint reflectance
rho_mol	Rayleigh reflectance (no glint)
t_d	Total diffuse transmittance (downward+upward)

1.2.6.1 Parameters

Name	Type	Description	Default
ds	xr.Dataset	The Dataset used for inputs/outputs. Must contain: - “altitude”: altitude above sea level - “horizontal_wind”: horizontal wind speed - “mus”: cosine of solar zenith angle - “muv”: cosine of viewing zenith angle - “raa”: relative azimuth angle (saa - vaa) - “rho_gc”: ground-corrected reflectance - “surface_pressure” or “sea_level_pressure”: atmospheric pressure	required
srf	xr.Dataset \| None	The sensor spectral response function (SRF).	`None`
**cfg	dict	Additional configuration parameters passed to `load_rayleigh_lut`.	`{}`

1.2.6.2 Returns

Name	Type	Description
	xr.Dataset	The input dataset with added variables: rho_rc, rho_mol_gli, rho_mol, t_d.
Note	this function shoud be deprecated in favour of the class RayleighCorrection