ARTS built-in documentation server

Workspace Method surfaceMapToLinearPolarisation

Description

Convert surface RT properties to a linear polarisation.

The properties converted are surface_emission and surface_rmatrix.

This method allows to set the surface properties to match a specific
linear polarisation for scalar calculation (stokes_dim=1). If you want
this, you have to call the method(s) setting up the surface RT
properties with stokes_dim set to 2, 3 or 4. This Stokes dimension
is below called local_stokes_dim.

The polarisation to apply is selected by *pol_angle*. This angle is
defined as in sensor_pol (i.e. 0 and 90 equal V and H, respectively).

If local_stokes_dim was set to 2, *surface_rmatrix is assumed to have
the structure:
   [ (rv+rh)/2 (rv-rh)/2; 
     (rv-rh)/2 (rv+rh)/2 ],
while if local_stokes_dim was set to 3 or 4, the mapping involves
several transformation matrices. The later case covers also couplings
between V/H and +-45 deg, and the mapping is described in the ARTS
theory guide, in section "Rotated modified Stokes vector".

In general it should suffice to set local_stokes_dim to 2, that gives
slightly faster calculations. A local_stokes_dim of 3 handles any case
correctly.

Authors: Patrick Eriksson

Synopsis

surfaceMapToLinearPolarisation(

surface_emission, surface_rmatrix, stokes_dim, pol_angle )

Variables

OUT+IN	surface_emission	(Matrix)	The emission from the surface.
OUT+IN	surface_rmatrix	(Tensor4)	The reflection coefficients for the directions given by surface_los to the direction of interest.
IN	stokes_dim	(Index)	The dimensionality of the Stokes vector (1-4).
GIN	pol_angle	(Numeric)	Polarisation angle, see above.