Fixing bug in AnalyticalAdvection

Author: erikvansebille

parcels/application_kernels/advection.py

@@ -210,7 +210,7 @@ def AdvectionAnalytical(particle, fieldset, time):  # pragma: no cover
                 yi += 1
                 eta = 0
 
-    particle.ei[:] = fieldset.U.ravel_index(xi, yi, zi)
+    particle.ei[:] = fieldset.U.ravel_index(zi, yi, xi)
 
     grid = fieldset.U.grid
     if grid._gtype < 2: