# ARTS built-in documentation server

## Workspace Method surfaceFlatScalarReflectivity

### Description

Creates variables to mimic specular reflection by a (flat) surface where surface_scalar_reflectivity is specified. This method assumes that the reflection at vertical and horizontal polarisation is identical. This assumption includes that there is no phase shift between polarisations. These assumptions result in that surface_emission is set to zero for positions corresponding to Q, U and V, and that surface_rmatrix becomes a diagonal matrix (with all elements on the diagonal equal to the specified reflectivity).

**Authors: **Patrick Eriksson

### Synopsis

surfaceFlatScalarReflectivity( | surface_los, surface_rmatrix, surface_emission, f_grid, stokes_dim, atmosphere_dim, rtp_pos, rtp_los, specular_los, surface_skin_t, surface_scalar_reflectivity ) |

### Variables

OUT | surface_los | (Matrix) | Downwelling radiation directions to consider in surface reflection. |

OUT | surface_rmatrix | (Tensor4) | The reflection coefficients for the directions given by surface_los to the direction of interest. |

OUT | surface_emission | (Matrix) | The emission from the surface. |

IN | f_grid | (Vector) | The frequency grid for monochromatic pencil beam calculations. |

IN | stokes_dim | (Index) | The dimensionality of the Stokes vector (1-4). |

IN | atmosphere_dim | (Index) | The atmospheric dimensionality (1-3). |

IN | rtp_pos | (Vector) | Position of a radiative transfer point. |

IN | rtp_los | (Vector) | Line-of-sight at a radiative transfer point. |

IN | specular_los | (Vector) | The specular direction (for reflection by a flat surface). |

IN | surface_skin_t | (Numeric) | Surface skin temperature. |

IN | surface_scalar_reflectivity | (Vector) | Surface reflectivity, assuming it can be described as a scalar value. |