# ARTS built-in documentation server

## Workspace Method ScatSpeciesMerge

### Description

Merges single scattering data of all scattering elements into one
element of bulk properties.
Before entering the scattering solver, this method prepares the
effective bulk single scattering properties of all scattering
elements. Done by calculating the particle number density weighted
sum of the single scattering properties of all scattering elements
per pressure level. Accordingly, pnd_field is resized to
[np, np, 1, 1], where np is the number of pressure levels inside
the cloudbox. The diagonal elements of the new pnd_field are set
to 1, all others to 0. scat_data is resized to np. Each new
scattering element represents the weighted sum of all particles at
one presssure level.
The method also adapts scat_species and scat_meta such that
they remain consistent with pnd_field and can pass
cloudbox_checkedCalc.
The method is suggested to be called directly after
pnd_fieldCalcFromParticleBulkProps (but also after
cloudbox_checkedCalc).
Its purpose is to speed up the scattering calculations.
This is an experimental method currently only working for limited
cases. All scattering elements must be of the same ptype and must
share the same f_grid, za_grid, and aa_grid. That is, the
scattering matrix, extinction matrix, and absorption vector of all
scattering elements must have the same dimensions. No interpolation
(apart from temperature) is performed.
This method can only be used with a 1D atmosphere.

**Authors: **Oliver Lemke

### Synopsis

ScatSpeciesMerge( | pnd_field, scat_data, scat_meta, scat_species, cloudbox_checked, atmosphere_dim, cloudbox_on, cloudbox_limits, t_field, z_field, z_surface ) |

### Variables