==== Case A 1: Rayleigh scattering ====

The most simple setup contains only one layer with scattering (non-absorbing) molecules. The radiance should be calculated for various geometries to check whether polarization is included correctly, in particular for special directions (e.g. solar zenith angle 0° or viewing zenith angle 0°). This test also checks, whether the Rayleigh depolarization factor is correctly included.

//Setup://

  * optical thickness of layer: 0.5
  * no molecular absorption
  * transmittance at bottom and reflectance at top of layer
  * cases:  sun positions (zenith angle //sza//, azimuth angle //saa//) and depolarization factors //depol//
    * //sza//=0°, //saa//=65°, //depol//=0.0
    * //sza//=30°, //saa//=0°, //depol//=0.03
    * //sza//=30°, //saa//=65°, //depol//=0.1
  * viewing zenith angles 
    * at bottom: //vza//: 0° - 80°, 5° increment
    * at top:    //vza//: 100° - 180°, 5° increment
  * viewing azimuth angle //vaa//: 0° - 360°, 5° increment	     

//Output format://

The output should be provided in an ascii file containing the following columns:
  depol altitude sza saa vza vaa I Q U V Istd Qstd Ustd Vstd

//altitude// contains the value 0 (bottom of layer) and 1 (top of layer).  

//I,Q,U,V// denote the Stokes vector. 

//Istd Qstd Ustd Vstd// are standard deviations of the Stokes vector components which should be provided for Monte Carlo models. If error estimates can not be provided, these columns may be omitted.

The result filename should be 'iprt_case_A1_MODEL.dat' and it should include the following header:

  # IPRT case A1 - Rayleigh scattering, 1 layer 
  # RT model: MODEL_NAME 
  # depol altitude sza saa vza vaa I Q U V Istd Qstd Ustd Vstd 


=== Results ===

//Difference plots// between the models IPOL, 3DMCPOL, SPARTA (previously named TROPOS), SHDOM, PSTAR and MYSTIC for the full radiation field:\\
{{:intercomparisons:phase_a:a1:diff_a1_3dmcpol.pdf|3DMCPOL}}\\
{{:intercomparisons:phase_a:a1:diff_a1_ipol.pdf|IPOL}}\\
{{:intercomparisons:phase_a:a1:diff_a1_tropos.pdf|SPARTA}}\\
{{:intercomparisons:phase_a:a1:diff_a1_shdom3.pdf|SHDOM}}\\
{{:intercomparisons:phase_a:a1:diff_a1_pstar.pdf|PSTAR}}\\

//Data// of all models (MYSTIC and 3DMCPOL include also standard deviation):\\
{{:intercomparisons:phase_a:a1:iprt_case_a1_mystic.dat|MYSTIC}}\\	 
{{:intercomparisons:phase_a:a1:iprt_case_a1_3dmcpol.dat|3DMCPOL}}\\
{{:intercomparisons:phase_a:a1:iprt_case_a1_ipol.dat|IPOL}}\\
{{:intercomparisons:phase_a:a1:iprt_case_a1_tropos.dat|SPARTA}}\\
{{:intercomparisons:phase_a:a1:iprt_case_a1_shdom3.dat|SHDOM}}\\
{{:intercomparisons:phase_a:a1:iprt_case_a1_pstar.dat|PSTAR}}\\