Hi all, Hi Jonas, Hi Richard,
All: If you do retrievals and using most recent version, you need to do
some small changes. The benefit is that you now also can retrieve
frequency corrections. See the ChangeLog message for a summary.
Jonas: With the commit I just made it should be possible to retrieve a
frequency shift using ARTS's OEM. The demo cfile should be pretty close
to what you want to do. That is, for details see:
I have done some testing, and all looked OK. Tell me if it works for you
Richard: I also made a small preparation if we ever will test to
retrieve spectroscopic variables. The mapping from the x-vector to
spectroscopic data is planned to be handled by x2artsSpectrosocopy (so
far a dummy WSM)
On 2018-09-18 15:18, Jonas Hagen wrote:
Thanks, of course this would be the proper approach and I hope that you
decide to implement instrument variables soon! This is the last piece in
the way of operational WIRA-C Wind retrievals with ARTS (and thus
without Matlab). Until then I will tinker with my patch.
On 18.09.2018 10:27, Patrick Eriksson wrote:
Some quick feedback, I am on a conference.
The variables that you can retrieve using ARTS-OEM so far are mainly
atmospheric quantities. To handle instrument variables I maonly left
for the future.
A constant frequency switch could be handled by shifting the
transitions as you tried to do. But frequency shifts are in fact an
instrument parameter, and moving the transitions will not work for
frequency stretch. So it seems to be time to implement a general way
to handle instrument variables. I will discuss with Simon, that is
also here at the conference.
For the moment I suggest that you do repeated linear inversions. And
adjusting your instrument frequencies after each linear inversion.
This should work with your extension of xaStandard. After some
iterations turn off the frequency switch and make a final inversion.
On 2018-09-17 17:22, Jonas Hagen wrote:
Hello ARTS Developers,
I'm trying to retrieve the Frequnecy Shift along with Wind with the
ARTS internal retrieval. To my understanding, this should work, but
support in xaStandard and x2artsStandard WSMs is missing and results
in an error: "Found a retrieval quantity that is not yet handled by
internal retrievals: Frequency"
For xaStandard(), the a priori Frequency Shift could easily be set to
zero after line 793 of m_oem.cc along with baseline and pointing.
For x2artsStandard(), maybe a new WSV would make sense (f_shift) and
the inversion_iterate_agenda would then call
abs_linesShiftFrequency(f_shift), similar to the baseline stuff?
I tried to implement it myself but got stuck with jacobian_quantities
and indices in x2artsStandard().
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