Hi all,

I am about to make a commit with some major changes. Richard, Jana and I have since the ARTS workshop worked on streamlining the radiative transfer methods, with the aim of having a coherent internal system covering both non-LTE and scattering, as well as simplifying and extending the calculation of analytical Jacobians. On the same time, some changes around ppath and auxiliary data have been introduced.

The methods iyEmissionStandard, iyTransmissionStandard and iyActiveSingleScat are largely rewritten. Most of the changes are just seen on the inside. There could be some small impact on the main outputs, iy and the resulting Jacobian. This due to slightly changed approach on how variables are averaged over a ppath step. But the differences we have seen so far all have been negligible.

On the other hand, a main change is that ppath is now calculated outside of the iy-methods. This for increased flexibility, and make it possible to avoid recalculating the ppath for e.g. iterative OEM inversions. This means that you need to call ppathCalc inside or outside of iy_main_agenda (if outside, you need Touch(ppath) inside the agenda). Note that the definitions in agendas.arts are updated and likely you don't need to care about this.

The treatment of "aux-variables" has also changed. Various atmospheric and radiative properties along the ppath, are now exported as pre-defined WSVs. These variables are denoted as ppvar_something (ppvar = propagation path variable). One example is ppvar_t, that gives you the temperature at each point of the ppath.

iy_aux_vars is now reduced to only treat variables that can be expressed as a matrix, as iy itself, such as (total) optical depth. As a consequence, iy_aux is now an ArrayOfMatrix. And all iy_ayx_vars can now be passed on to y_aux. However, I have not got time to resurrect all iy_aux_vars (such as Faraday rotation), and little testing done. So don't expect to much of this part yet.

Some documentation updated, but a lot to on that side ...

We think these changes will make it easier to use and develop ARTS in the long run, but could cause some problems now. Tell us if you obtain any suspicious results, or if any feature you use has disappeared.


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