Hi all, I use Qpack to retrieve tropospheric water vapour profiles from spectra of our 22GHz radiometer MIAWARA. The setup is like this: - nonlinear Marquardt-Levenberg - polyfit (1st grade, coefficients are part of the state vector and are retrieved)
Till recently, I used the old Qpack1 and it worked well. Some months ago I started trying to setup the same retrieval with QPack2. As it didn' work well and I had a lack of time, I gave it then up. Now I retried it and it works quite well with QPack2 after setting the retrieval unit to logrel (implicitly the Qpack1-retrieval was set to logrel, what I only discovered thanks to Patriks suggestions). Still the results with QPack2 differ from the results with QPack1, as the vmr is generally up to 20% too low in upper troposphere and 10-20% too high in lower troposphere. More detailed analyses revealed that there is a difference between the weighting functions in Qpack1 and Qpack2 (even in the first iteration step), the tropospherical maxima of the weighting functions in Qpack2 are generally up to 10% lower than in Qpack1. Does anyone have an idea where this difference could come from? (spectroscopy and pTz setup are identical) Maybe it has to do something with the sensor/backend-part, which should in principle be the same for both. In Qpack1 the H-matrix (y=H*F(x,b)) summarizes the entire sensor/backend stuff. I wanted to compare H with its equivalent in QPack2, but I could not find it. Does there exist a similar H-matrix in Arts2/QPack2? Regards René -- René Bleisch Institute of Applied Physics University of Bern Sidlerstr.5 3012 Bern Switzerland Phone: +41 31 631 89 59 Mail: [email protected] _______________________________________________ qpack mailing list [email protected] https://www.sat.ltu.se/mailman/listinfo/qpack
