Calculation of JFAC

[rs028]

There 2 main problems with the calculation of JFAC:

1. zeros or infinite values created by the division (see also JFAC crashes when calculated from constrained jNO2 #16).
2. different photolysis rates have different widths (due to different absorption cross sections).

The first is probably solvable with simple modifications to the code (e.g. appropriate threshold for COSX, see #276).

The second requires a different approach and/or a new algorithm to calculate JFAC.

[rs028]

With regard to the second point, this paper https://pubs.rsc.org/en/content/articlehtml/2022/ea/d2ea00072e may be helpful.