Hello René, I think Patrick can answer your questions best, but a quick comment on the H-Matrix. The ARTS-2 variable for it is called "sensor_response". For documentation, see: http://www.sat.ltu.se/arts/docserver/variables/sensor_response .
To check whether the problem really is in the sensor part, or rather in the monochromatic pencil-beam Jacobians, you could as a first step turn off the sensor (method sensorOff in ARTS-2). One possibility is the conversion to brightness temperatures, ARTS-1 could calculate Jacobians only in Rayleigh-Jeans BT units, whereas ARTS-2 offers also Planck. Also, it can make a difference whether you do the BT conversion before or after the sensor part (both options are possible, but one will be more correct, depending on how your sensor is defined). /Stefan On Jun 15, 2011, at 12:47 , Rene Bleisch wrote: > 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 _______________________________________________ qpack mailing list [email protected] https://www.sat.ltu.se/mailman/listinfo/qpack
