ARTS built-in documentation server

Workspace Method scat_data_singleTmatrix


A basic interface to Mishchenko's T-matrix code linked to ARTS.

The method performs a T-matrix calculation for a single scattering
element, i.e. a combination of particle shape, size, aspect ratio
and orientation.

Particle shape (*shape*) has two options:
   "spheroidal" and "cylindrical"

Particle size (*diameter_volume_equ*) is given as the equivalent
volume sphere diameter. That is, the diameter obtained if all the
particle's material is rearranged into a (solid) sphere.

Particle aspect ratio ar (*aspect_ratio*) is a numeric value, defined
according to Mishchenko's definition as ratio of horizontal axis a to
vertical (rotational) axis b: ar=a/b. That is, oblates have ar>1,
prolates ar<1.
Perfect spheres (spheroidals with ar=1) can trigger numerical issues.
To avoid these, we internally increase their aspect ratio by 1e-6,
i.e. turning perfect spheres into very light oblates.

Particle type (*ptype*) has two options:
   "totally_random" and "azimuthally_random"
For totally randomly oriented particles, *data_aa_grid* is not taken
into account (but a Vector type container needs to be passed).

For further information on how aspect ratio and the different shapes
and orientations are defined, see the documentation of the T-matrix
code found

Regarding *ndgs*, we refer to the this comment from the documentation:
   "Parameter controlling the number of division points
   in computing integrals over the particle surface.
   For compact particles, the recommended value is 2.
   For highly aspherical particles larger values (3, 4,...)
   may be necessary to obtain convergence.
   The code does not check convergence over this parameter.
   Therefore, control comparisons of results obtained with
   different NDGS-values are recommended."

Authors: Johan Strandgren, Patrick Eriksson


scat_data_singleTmatrix( scat_data_single, scat_meta_single, complex_refr_index, shape, diameter_volume_equ, aspect_ratio, mass, ptype, data_f_grid, data_t_grid, data_za_grid, data_aa_grid, precision, cri_source, ndgs, robust, quiet )


OUTscat_data_single(SingleScatteringData)Structure for the single scattering data.
OUTscat_meta_single(ScatteringMetaData)Structure for the scattering meta data.
INcomplex_refr_index(GriddedField3)Complex refractive index (n) data.
GINshape(String)Particle shape. Options listed above.
GINdiameter_volume_equ(Numeric)Particle volume equivalent diameter [m]. See defintion above.
GINaspect_ratio(Numeric)Particle aspect ratio.
GINmass(Numeric, Default: NaN)Particle mass. This information is just included in the meta data, and does not affect the T-matrix calculations.
GINptype(String)Particle type/orientation. Options listed above.
GINdata_f_grid(Vector)Frequency grid of the scattering data to be calculated.
GINdata_t_grid(Vector)Temperature grid of the scattering data to be calculated.
GINdata_za_grid(Vector)Zenith angle grid of the scattering data to be calculated.
GINdata_aa_grid(Vector, Default: [])Azimuth angle grid of the scattering data to be calculated.
GINprecision(Numeric, Default: 0.001)Accuracy of the computations.
GINcri_source(String, Default: "Set by user, unknown source.")String describing the source of complex_refr_index, for inclusion in meta data.
GINndgs(Index, Default: 2)See above. So far only applied for random orientation.
GINrobust(Index, Default: 0)Continue even if individual T-matrix calculations fail. Respective scattering element data will be NAN.
GINquiet(Index, Default: 1)Suppress print output from tmatrix fortran code.