surface.cc

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/* Copyright (C) 2012
   Patrick Eriksson <Patrick.Eriksson@chalmers.se>

   This program is free software; you can redistribute it and/or modify it
   under the terms of the GNU General Public License as published by the
   Free Software Foundation; either version 2, or (at your option) any
   later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307,
   USA. */




/*===========================================================================
  === File description 
  ===========================================================================*/

/*===========================================================================
  === External declarations
  ===========================================================================*/

#include <cmath>
#include "auto_md.h"
#include "check_input.h"          
#include "complex.h"          
#include "geodetic.h"          
#include "matpackI.h"
#include "math_funcs.h"
#include "physics_funcs.h"
#include "workspace_ng.h"
#include "surface.h"





/*===========================================================================
  === The functions (in alphabetical order)
  ===========================================================================*/



Numeric calc_incang(
   ConstVectorView   rte_los,
   ConstVectorView   specular_los )
{
  return ( 180-abs(rte_los[0]) + abs(specular_los[0]) ) / 2;
}




void surface_specular_R_and_b(
              Workspace&   ws,
              MatrixView   surface_rmatrix,
              VectorView   surface_emission,
        const Complex&     Rv,
        const Complex&     Rh,
        const Numeric&     f,
        const Index&       stokes_dim,
        const Numeric&     surface_skin_t,
        const Agenda&      blackbody_radiation_agenda )
{
  assert( surface_rmatrix.nrows() == stokes_dim );
  assert( surface_rmatrix.ncols() == stokes_dim );
  assert( surface_emission.nelem() == stokes_dim );

  // Expressions are derived in the surface chapter in the user guide

  surface_rmatrix   = 0.0;
  surface_emission  = 0.0;

  Vector   B;
  blackbody_radiation_agendaExecute( ws, B, surface_skin_t, Vector(1,f), 
                                     blackbody_radiation_agenda ); 

  const Numeric   rv    = pow( abs(Rv), 2.0 );
  const Numeric   rh    = pow( abs(Rh), 2.0 );
  const Numeric   rmean = ( rv + rh ) / 2;

  surface_rmatrix(0,0) = rmean;
  surface_emission[0]  = B[0] * ( 1 - rmean );

  if( stokes_dim > 1 )
    {
      const Numeric   rdiff = ( rv - rh ) / 2;

      surface_rmatrix(1,0) = rdiff;
      surface_rmatrix(0,1) = rdiff;
      surface_rmatrix(1,1) = rmean;
      surface_emission[1]  = -B[0] * rdiff;

        if( stokes_dim > 2 )
          {
            const Complex   a     = Rh * conj(Rv);
            const Complex   b     = Rv * conj(Rh);
            const Numeric   c     = real( a + b ) / 2.0;

            surface_rmatrix(2,2) = c;
      
            if( stokes_dim > 3 )
              {
                const Numeric   d     = imag( a - b ) / 2.0;

                surface_rmatrix(2,3) = d;
                surface_rmatrix(3,2) = -d;
                surface_rmatrix(3,3) = c;
              }
          }
    }
}