[arts-users] Zeeman Effect ARTS 2.4 (with qpack)

[witali.krochin]

Hi everyone

I am trying to initialize the Zeeman effect in ARTS 2.4 using the updated qpack 
version.
The molecule of interest is oxygen, the frequency range is around 52-53GHz (the 
rotational emission lines around 52GHz and 53 GHz).

I included the method "propmat clearskyAddZeeman" in the propmat clearsky 
Agenda.

However I strugle with setting the quantum numbers and constants. There is a 
Zeeman file in the xml Data folder. For me it seems that the required constants 
are stored there. The README tell me to use the methods:

- abs_lines_per_speciesSetZeemanCoefficients or
- abs_linesSetZeemanCoefficients

I checked the built in documentary, but still not understand how to use these 
methods.
For example I don't know in which workspace variable the information should be 
feeded in.

In Arts 2.2  I used readXML to read the file "Zeeman_constants.xml" (was 
included in xml data) and feeded the data in the Variable WSMS_AT_START.

Furhtermore there was an Zeeman demo in the older atmlab version. That was very 
helpfull and seems to be missed now.

Can anyone help me to set this constants? Just a few example lines would help.

Best regards
Witali


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Re: [arts-users] arts_users.mi Digest, Vol 53, Issue 1

[Stefan Buehler]

Dear Renish,

yes, these are good points by Stuart. The metmm setup is not optimized 
for the oxygen bands. My understanding is that Alex, here in Cc, is 
currently testing the different oxygen setups. Alex, perhaps you could 
also comment?


For the water vapor, note that Alex also made tweaks to some line 
parameters according to recent literature (at the time, as described in 
the README file). The reason to stick with that setup would be because 
it has been compared to observations. I can’t say about the newer 
HITRAN and CKDMT320. It may be equally good or even better. But not 
necessarily. That’s a bit the problem with these recommendations 
it’s a bit of a moving target.


Best wishes,

Stefan

On 12 Nov 2020, at 12:15, Fox, Stuart wrote:


Hi Renish/Stefan,

Looking at the controlfile Stefan recommends I have a couple of 
concerns/questions. Firstly, it looks to me that the Oxygen absorption 
set-up is using line parameters from the catalog file (which I'm 
assuming is HITRAN-2012?), but does not have any line mixing. I would 
expect this to lead to problems in the 50-60GHz oxygen band and have 
an impact out into the 89GHz window region. My understanding was that 
it was simplest to use the "O2-TRE05" complete absorption model for 
oxygen which does include the line mixing effects?


The water vapour set-up is probably fine, although my preference is to 
use the values from the AER catalog which has a couple of tweaks to 
better fit some atmospheric observations. I think the recent releases 
are almost the same as HITRAN-2016, but maybe not HITRAN-2012? Recent 
versions of ARTS also have the CKDMT320 continuum (courtesy of Emma 
Turner) and I've found that seems to give a reasonable match to much 
of our airborne data.


Regards,

Stuart

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Today's Topics:

   1. Choosing the right Continua models/spectroscopy data
  (Thomas,Renish)
   2. Re: Choosing the right Continua models/spectroscopy   data
  (Stefan Buehler)


--

Message: 1
Date: Thu, 12 Nov 2020 04:13:56 +
From: "Thomas,Renish" 
To: "arts_users.mi@lists.uni-hamburg.de"

Subject: [arts-users] Choosing the right Continua models/spectroscopy
data
Message-ID:



Content-Type: text/plain; charset="iso-8859-1"


Hi Everyone,

I had a question about selecting the best Continua models/spectroscopy 
lines for the most accurate simulation results.


My main species of interest is "H2O" and I am simulating an airborne 
sensor. The difference in brightness temperatures when I use the 
"H2O-PWR98" vs. "H2O" lines from the Perrin database along with the 
PWR98 model is greater than about 10 degrees around the 183 GHz water 
vapor lines.


So, my question is, what is the best strategy on choosing the continua 
models and spectroscopic data around the absorption lines and in the 
window region (Away from absorption lines).


My region of interest is 50-300 GHz.

Also, what are the recommended spectroscopic lines and for what 
applications are they most suited for. Example : Perrins, HITRAN.


Cheers,
Renish

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Message: 2
Date: Thu, 12 Nov 2020 09:58:47 +0100
From: "Stefan Buehler" 
To: "Thomas,Renish" 
Cc: "arts_users.mi@lists.uni-hamburg.de"

Subject: Re: [arts-users] Choosing the right Continua
models/spectroscopy data
Message-ID: <62af22b7-302e-4e9f-a067-1f586d683...@uni-hamburg.de>
Content-Type: text/plain; charset="UTF-8"; format=flowed

Dear Renish,

for microwave water vapor instruments I would recommend the settings 
from controlfiles/instruments/metmm (in the ARTS distro), which were 
developed by Alex Bobryshev and used for this paper:


Bobryshev, O., S. A. Buehler, V. O. John, M. Brath, and H. Brogniez 
(2018), Is there really a closure gap between 183.31 GHz satellite 
passive microwave and