Hi Emma,

No problem, I understand that this is far from obvious.

In short, qarts is an attempt to make a relatively general interface to 
ARTS. What you can do with qpack2 is more restricted, but tries to 
streamline the retrieval procedure. In a way, qpack2 is sub-set of qarts 
where some things happen "automatically".

There are some comments in the qpack2 pdf document. Anyhow, for how to 
use qarts (without doing retrievals), see e.g. qarts_demo2 in the demos 
folder. You will recognise the Q structure. And to run arts there are 
some different functions depending on what you want to do, but arts_y is 
by far the most important one.

That is, [y,y_aux] = arts_y( Q ); is matlab code.

If you have set up a Q to be used with qpack2, you need to make some 
modifications. At least you need to set SENSOR_POS and SENSOR_LOS. The 
rest depends on how you have set VMRs etc. in Q. Sorry, can not give you 
a complete answer there. The best help is the demo scripts in /demos. 
Note e.g. that arts_y is used in qpack2_demo to generate a test 
measurement, to be inverted.

Bye,

Patrick

On 2014-11-27 15:51, Turner, Emma C. wrote:
> Hi Patrick,
>
> Apologies for my ignorance but what is the more general qarts system?
> Does that mean applying the below code snippet in the arts C++ code?
>
> Thanks Emma ________________________________________ From: Patrick
> Eriksson [[email protected]] Sent: 27 November 2014 14:33
> To: Turner, Emma C. Cc: [email protected] Subject: Re: [Qpack]
> Obtaining Y units of Transmission from q_pack
>
> Hi Emma,
>
> CC to qpack list as this is of general interest. And we prefer if
> all questions go to any of the arts and qpack lists.
>
> The answer is:
>
> [y,y_aux] = arts_y( Q );
>
>
> There is now way to obtain the aux vars by qpack2. If you want this
> information you must use the more general qarts system, where then
> arts_y is the function to use. Or, of course, using arts directly.
>
> Bye,
>
> Parick
>
>
>
>
> On 2014-11-27 15:07, Turner, Emma C. wrote:
>> Thanks Patrick,
>>
>> It runs now, how do I extract the data for tau from Y?
>>
>> Bye, Emma ________________________________________ From: Patrick
>> Eriksson [[email protected]] Sent: 27 November 2014
>> 13:50 To: Turner, Emma C.; [email protected] Subject: Re:
>> [Qpack] Obtaining Y units of Transmission from q_pack
>>
>> Dear Emma,
>>
>> Uuups, a piece of documentation that has not been updated. I will
>> fix that.
>>
>> I assume you use iyEmissionStandard, then you can check out the aux
>> var options by
>>
>> arts -d iyEmissionStandard
>>
>> That is, the option is
>>
>> Q.IY_AUX_VARS           = { 'Optical depth' };
>>
>> that gives you tau, which you easiliy can covert to transmission.
>>
>> Bye,
>>
>> Patrick
>>
>>
>> On 2014-11-27 14:43, Turner, Emma C. wrote:
>>> Dear mailing list,
>>>
>>> Using the ARTS forward model to simulate a ground-based sensor I
>>> am looking to obtain total Transmission values (in %) in addition
>>> to Brightness Temperature values. ARTS leads me to believe I can
>>> do this using iy_aux_vars where in the documentation it states
>>> that "Transmission, total" is a valid option when I use ycalc  -
>>> http://www.sat.ltu.se/arts/docserver-stable/variables/iy_aux_vars
>>>
>>>
>>>
I'm having trouble with the syntax in q_pack2, when I include
>>>
>>> Q.IY_UNIT             = 'PlanckBT'; Q.YCALC_WSMS          = {
>>> 'yCalc' }; Q.IY_AUX_VARS           = { 'Transmission' }
>>>
>>> to the code it complains that, 'For calculations using yCalc,
>>> *iy_aux_vars* can not include variables of along-the-path or
>>> extinction matrix type.' but when I add 'Total' like it suggests
>>> in the documentation
>>>
>>> Q.IY_AUX_VARS           = { 'Transmission', 'Total' }
>>>
>>> it complains that, 'In *iy_aux_vars* you have included: "Total".
>>> This choice is not recognized.'
>>>
>>> Can someone help me?
>>>
>>> Many thanks Emma
>>>
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>>
>> This message (and any attachments) is for the recipient only. NERC
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>>
>
> This message (and any attachments) is for the recipient only. NERC is
> subject to the Freedom of Information Act 2000 and the contents of
> this email and any reply you make may be disclosed by NERC unless it
> is exempt from release under the Act. Any material supplied to NERC
> may be stored in an electronic records management system.
>
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