Hi Patrick, Thanks a lot. I am trying to retrieve ozone profiles considering the covariance matrix of temperature and water vapour. With 'good shape' I mean that it is around a number in the whole frequency range (straight). Now I included a calculation of a baseline in each iteration and it seems to improve the residual. I will also try to set POLYFIT in Q.DEFINITIONS.m. Thanks again. Regards Facundo
2015-12-06 10:05 GMT-03:00 Patrick Eriksson <[email protected]>: > Hi Facundo, > > I am writing again because I did that I said in the previous mail and >> retrieved ozone profiles are not bad, but the residual (yf-y) is not >> around zero...It goes down to around 0.3 (the shape is good, but goes >> down). It happens when I introduce the error related to T and H2O, and >> also when I introduce only T or only H2O. Residual are very similar in >> this 3 cases (T and H2O, T or H2O). When I do not include these errors >> (only considering noise) it does not happen. I was looking for what is >> wrong and I could not find it. Do you have any suggestion about it? >> > > This is not easy to answer without having all the details at hand. Exactly > how you calibrate the measurements, exact retrieval settings etc. Some > questions: > > * What do you mean with good shape of the residual? > > * Do you make a non-linear retrieval? With T or H2O you might need to > iterate to find the exact solution. > > * Do you include any POLYFIT? To include POLYFIT is quite standard, to > reflect that your calibration newer is perfect. It is likely that the > complete spectrum is wrong with roughly 1K just due to calibration issues. > > > On the other hand, what is exactly the use of the variable 'xnorm'? >> > > It is a feature to avoid numerical problems if your quantities have very > different values. If you use Qpack, this is activated automatically, when > could be needed. > > Bye, > > Patrick >
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