[RegCNET] Dust mixing ration (Trac1, Trac2, Trac3, Trac4) in CHE output files

[Giuliani Graziano]

> Dear Fabien,
> I have the problem of getting Trac1, Trac2, Trac3 and Trac4 in CHE output
> file even using the given regcm.in files for DUST runs of the Testing
> folder. Please try to sort out the problem.
[...]

The NetCDF output format has the "trac" variable joined for all the
tracers in a 5 dimensional variable, named trac, with standard name
"atmosphere_mixing_ratio_of_tracer", units of kg kg-1.

The dimensions of this variable are time, tracer, kz, iy, jx

Convince yourself of this using the ncdump helper program, or plot the
data using GrADS via the helper program.

Ciao!

Graziano,