surfaceMapToLinearPolarisation

Workspace.surfaceMapToLinearPolarisation(self: pyarts.arts._Workspace, surface_emission: Optional[Union[pyarts.arts.WorkspaceVariable, pyarts.arts.Matrix]] = self.surface_emission, surface_rmatrix: Optional[Union[pyarts.arts.WorkspaceVariable, pyarts.arts.Tensor4]] = self.surface_rmatrix, stokes_dim: Optional[Union[pyarts.arts.WorkspaceVariable, pyarts.arts.Index]] = self.stokes_dim, pol_angle: Union[pyarts.arts.WorkspaceVariable, pyarts.arts.Numeric], verbosity: Optional[Union[pyarts.arts.WorkspaceVariable, pyarts.arts.Verbosity]] = self.verbosity) → None

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:

\[\begin{split}\begin{array}{cc} (rv+rh)/2 & (rv-rh)/2 \\ (rv-rh)/2 & (rv+rh)/2 \end{array}\end{split}\]

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.

Author(s): Patrick Eriksson

Parameters:

• surface_emission (Matrix, optional) – The emission from the surface. See surface_emission, defaults to self.surface_emission [INOUT]

• surface_rmatrix (Tensor4, optional) – The reflection coefficients for the directions given by. See surface_rmatrix, defaults to self.surface_rmatrix [INOUT]

• stokes_dim (Index, optional) – The dimensionality of the Stokes vector (1-4). See stokes_dim, defaults to self.stokes_dim [IN]

• pol_angle (Numeric) – Polarisation angle, see above. [IN]

• verbosity (Verbosity) – ARTS verbosity. See verbosity, defaults to self.verbosity [IN]