Streamlines in spherical coordinates

I am trying to plot streamlines of a 3D vector field in spherical coordinates. I have the three components (Br,Bt,Bp) loaded as separate scalar fields from a netcdf file with standard CF convention (ie with latitude, longitude and radial coordinates). This seems to be recognized by Paraview, ie I get indeed a spherical grid. Next, in order to use the streamline filter, I need first to apply the “Cell to point data” filter, and then to combine the scalar components into a vector using the Calculator filter as
which does not result in the proper vector field (I know what the answer should look like). I guess the problem is that i/j/kHat are the unit vectors of the Cartesian reference system, not the one of the spherical coordinate system. Is there a straightforward way to build the vector field from the scalar components in spherical coordinates?

You will need to convert your field to cartesian coordinates first.

Hi Mathieu,
thanks for your quick reply! Can you shortly elaborate on your suggestion? I am not sure that I understand that correctly: I have a spherical grid, properly recognized by paraview, and in order to visualize streamlines of a vector field given in spherical coordinates I need to convert that to Cartesian? If this is what you suggest, I did try it but the streamlines are still incorrect. I can imagine this is a common configuration, a reference to an example would be equally good.
Thanks for your time

There is no automatic way to do this yet.
Some ressources :

Thank you very much Mathieu, i will work my way through those. Have a nice day