[ARTS-2.6] Bugfix Rayleigh scattering phase matrix (#780)

atmtools · Jun 20, 2024 · 1576f9a · 1576f9a
2 parents c61c851 + 6bdd15a
commit 1576f9a
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Showing 2 changed files with 9 additions and 16 deletions.
diff --git a/controlfiles-python/artscomponents/gasscattering/TestClearsky_StarGasScatteringRayleigh.py b/controlfiles-python/artscomponents/gasscattering/TestClearsky_StarGasScatteringRayleigh.py
@@ -215,7 +215,7 @@ def starARTS_clearsky(f_grid, sensor_pos, sensor_los, sun_pos, Reflectivity,
                               stokes_dim=1)
 
     # Reference data
-    yREFERENCE = np.array([3.94192129256117e-13])
+    yREFERENCE = np.array([3.92491800384289e-13])
 
     # Compare with reference
     ws.CompareRelative(y, yREFERENCE, 1e-6)
diff --git a/src/m_gas_scattering.cc b/src/m_gas_scattering.cc
@@ -159,26 +159,19 @@ void gas_scattering_matRayleigh(TransmissionMatrix& gas_scattering_mat,
       // Rayleigh phase matrix in scattering system
       Vector pha_mat_int = calc_rayleighPhaMat(theta_rad, stokes_dim);
 
-      // transform the phase matrix
-      Matrix pha_mat(stokes_dim, stokes_dim, 0.0);
-
       // account for depolarization factor
       Numeric delta =
           (1 - depolarization_factor) / (1 + 0.5 * depolarization_factor);
       Numeric delta_prime =
           (1 - 2 * depolarization_factor) / (1 - depolarization_factor);
-      Vector depol(6, 0.0);
-
-      switch (stokes_dim) {
-        case 4:
-          depol[5] = 1;
-          pha_mat_int[5] *= delta_prime;
-          [[fallthrough]];
-        case 1:
-          depol[0] = 1;
-          depol *= 1 - delta;
-          pha_mat_int += depol;
-      }
+
+      // add depolarization to phase matrix according to Hansen and Travis (1974)
+      pha_mat_int *= delta;
+      pha_mat_int[0] += (1 - delta);
+      if (stokes_dim == 4) pha_mat_int[5] *= delta_prime;
+
+      // transform the phase matrix
+      Matrix pha_mat(stokes_dim, stokes_dim, 0.0);
 
       pha_mat_labCalc(pha_mat,
                       pha_mat_int,