The current dev-branch also has this difference in it. I will try to
investigate tomorrow.
(There are even -250 K in one place of your results. So clearly something
weird is happening here.)
With hope,
//Richard
Den tors 6 maj 2021 kl 15:00 skrev Fox, Stuart :
> Dear ARTS developers,
>
>
>
> I’m trying to understand some changes to clear-sky simulations when moving
> to ARTS v2.4 and have noticed that there seems to be a difference in how a
> cutoff frequency for absorption lines is handled. I’ve put a basic example
> illustrating this at https://github.com/stuartfox/arts-cutoff-problem,
> which has the controlfiles I’ve used at ARTS v2.4 and ARTS v2.3.1277 and
> the input data I used.
>
>
>
> The example performs a clear-sky simulation using only water vapour
> absorption lines read from an ARTSCAT-3 format file (which was originally
> derived from the HITRAN-style file provided by AER). Note that Ive used a
> slightly silly cutoff frequency of 20GHz around each line to highlight the
> problem; it shows small (but non-negligible) differences in brightness
> temperature around the main water vapour lines, and at v2.4 the output also
> has a couple of very large negative brightness temperatures which leads me
> to think there may be a bug in that version. If I remove the line cutoff
> (by changing line 27 of the v2.4 controlfile to cutoff_option="None" and
> line 25 of the v2.3 controlfile to cutoff=-1) then I get very good
> agreement between the two versions.
>
>
>
> Is this a problem with ARTS or am I doing something wrong with my setup?
>
>
>
> Thanks,
>
>
>
> Stuart
>
