Dear Patrick and Ole Martin, I am writing again from this old mail because I have a problem in Qpack2 that I think that it is related with the setting that Ole Martin proposed in the previous mail, but I am not sure. To explain it I want to share the experiment that I did:
1. I set Y.Z_PLATFORM=12Km. My O3 a-priori profile goes from ground to 90km (I will call it 'APRIORI') [So, then of the 3. step I will have a simulated spectrum from the a priori (SPECTRUM_AP)] 2. I make a synthetic profile (taking it as O3 in the atmosphere or true state vector) which is same as the a priori profile, but I add a delta O3 (0.5ppm) at 7km (PROFILE_7km). So, I arrange a syntetic "true state" that I know. Then I calculate a spectrum (SPECTRUM_7km) from PROFILE_7km using QPack2/ARTS. I took this spectrum as the measurement. 3. I run Qpack2/ARTS inserting SPECTRUM_7km as measurement, and APRIORI as a priori profile and stop in the first iteration. (Note that I am setting Y.Z_PLATFORM=12km, and I the add a delta O3 the ozone in the true state vector at 7km. ) The result was that SPECTRUM_AP (yf) is a little bit diferent to SPECTRUM_7km (y). I think that it must be equal ( SPECTRUM_AP = SPECTRUM_7km) because the Y.Z_PLATFORM is above to 7km and a perturbation at 7km should not affect the retrieval. Is it correct? the Q is: Why changes below Y.Z_PLATFORM in the true state vector affect the retrieval? Thanks in advance. Best regards Facundo 2014-11-18 21:58 GMT+09:00 Ole Martin Christensen < [email protected]>: > Hi, > > the standard way of doing this is to do it before you do the retrieval. > You manually adjust your measured spectra assuming that your measured > opacity is correct (called "tropospheric correction"). > > In arts you can then model your instrument as being above the troposphere, > i.e. by setting the altitude of your sensor (Y.Z_PLATFORM if you use > qpack2) to 15 km. The simulated spectra can then be compared to your > corrected spectra for a successful retrieval. > > Another option is using continuum models to model O2, H2O(gas and/or > liquid) across the tropopause. These can be added by adding by writing e.g.: > > Q.ABS_SPECIES(2).TAG = { 'H2O-PWR98' }; > > With a following fields like Q.ABS_SPECIES(2).ATMDATA, and > Q.ABS_SPECIES(2).GRIDS. > > However, in general the manual tropospheric correction is the most > commonly used method, as it is simpler, and would recommend starting with > this. > > If anything is unclear please feel free to send more questions. For > further inquiries I would also strongly recommend the qpack and arts > mailinglists. > > https://www.sat.ltu.se/mailman/listinfo/qpack > https://www.sat.ltu.se/mailman/listinfo/arts-users > > Regards > > Ole Martin > > > ------------------------------ > *From:* Facundo Orte [[email protected]] > *Sent:* Tuesday, November 18, 2014 12:44 PM > *To:* Patrick Eriksson > *Cc:* Ole Martin Christensen > *Subject:* Re: Question about ARTS > > Dear Patrick Eriksson, > thanks for your reply. > The MWR is installed in Río Gallegos city (Latitud: -51° 36' 02,03",Longitud: > -69° 19' 09.96") since 2011. The name of the observatory is "Observatorio > Atmosferico de la Patagonia Austral" which depends to Lidar Division > (CEILAP). You can see the site in this link > http://www.division-lidar.com.ar/sitios_rg.html. It is quite near to > Ushuaia. > The MWR is working at 110.83GHz. For calculate the opacity from the MWR we > can use, for example, the method described by Zafra et al. (Zafra, R. L., > Parrish, A., Solomon, P. M and Barrett, J. W., A Quasi-continuous record of > atmospheric opacity at λ=1.1 mm over 34 days at Mauna Kea Observatory, > International Journal of infrared and Millimeter Waves, Vol. 4, No 5, > 1983.). Comparisons between the opacity measured and obtained from > radiosonde profiles presents good agreement. > If I may to introduce the measured opacity (by MWR) as input of ARTS maybe > it could be good. My question is: where can I input the measured opacity > in ARTS? > Thanks a lot > Best Regards > Facundo > > > 2014-11-17 15:53 GMT-03:00 Patrick Eriksson <[email protected]> > : > >> Dear Facundo Orte, >> >> Nice to hear that you have started to use Qpack. >> >> Getting curious, where exactly is the radiometer placed? Did some >> travelling around Latin America in the 90-ies. Passed e.g. Uschaia. What >> frequency is the radiometer using? >> >> Don't understand your question exactly. How do you observe an opacity >> with the radiometer? I don't know how that could be done. Measured >> brightness temperatures can be converted to an opacity, but then it is >> better to use the original Tb-data. Or is the opacity determined by some >> other instrument. If you describe this closer, we will try to help you. >> >> Regards, >> >> Patrick >> >> >> >> On 2014-11-17 19:05, Facundo Orte wrote: >> >>> Dear Patrick Eriksson, >>> My name is Facundo Orte and I am a PhD student of the Lidar Division of >>> CEILAP (Laser Research Center) from Argentina (division-lidar.com.ar >>> <http://division-lidar.com.ar>). >>> I am writing you because in our laboratory there is a Millimiter Wave >>> Radiometer (MWR) instaled in South Patagonia, near to the spring ozone >>> hole, and we retrieve ozone profiles with it. To analyze the signal we >>> are trying to use the ARTS model that you and your team developed. I am >>> using MATLAB to introduce inputs changing Q.DEFINITION.m function and I >>> retrieve some profiles but there are quite close to "a priori" ozone >>> profile (I am using MLS climatology as a priori O3 profile). I think >>> that it is because I do not have well caracterized the atmosphere and I >>> am trying to do that. For example, at this moment, I do not know how to >>> introduce the opacity measured for the MWR instrument from MATLAB as >>> input and I think that it is an important parameter to introduce. >>> Could you help me with it? Do you know how I can to introduce the >>> opacity from MATLAB? >>> I will very appreciate if you can help me with it. >>> Thank you in advance >>> Best regards >>> Facundo Orte >>> >>> >>> >>> >
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