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LWC C ALIBRATION The Long Wavelength Channel calibration procedure is currently on its version 4The Long Wavelength Channel calibration procedure is currently.

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Presentation on theme: "LWC C ALIBRATION The Long Wavelength Channel calibration procedure is currently on its version 4The Long Wavelength Channel calibration procedure is currently."— Presentation transcript:

1 LWC C ALIBRATION The Long Wavelength Channel calibration procedure is currently on its version 4The Long Wavelength Channel calibration procedure is currently on its version 4 It is the result of an extensive study of the thermal/statistical behavior of PFSIt is the result of an extensive study of the thermal/statistical behavior of PFS This procedure has been extensively validated and is currently providing good results ( H 2 O, temperature vertical profiles, ice/dust/clouds studies, surface temperature maps )This procedure has been extensively validated and is currently providing good results ( H 2 O, temperature vertical profiles, ice/dust/clouds studies, surface temperature maps ) Provided curves can be used at thermal regime condition (> 90% of data) Provided curves can be used at thermal regime condition (> 90% of data) Interpolation is required for non-regime conditions Interpolation is required for non-regime conditions Residual issues may occur (tilts and wiggles, phase). See Giuranna this afternoon.Residual issues may occur (tilts and wiggles, phase). See Giuranna this afternoon. MEx and VEx DATA WORKSHOP - PFS and SOIR experiments - 27 June - 1st July 2011, ESA/ESAC,Spain

2 LWC calibrations V1 had some Zero-Level problems These problems have been solved with Calibration procedure V2 C ALIBRATION H ISTORY (1/2) MEx and VEx DATA WORKSHOP - PFS and SOIR experiments - 27 June - 1st July 2011, ESA/ESAC,Spain

3 Minor differences between V2 and V3 (better spectral calibration; new geometries)Minor differences between V2 and V3 (better spectral calibration; new geometries) Instrumental artifacts still present in V3, expecially above 800 cm -1Instrumental artifacts still present in V3, expecially above 800 cm -1 C ALIBRATION H ISTORY (2/2) Orbit 100 average of 200 spectra Fixed with Calib_v4 MEx and VEx DATA WORKSHOP - PFS and SOIR experiments - 27 June - 1st July 2011, ESA/ESAC,Spain

4 T HERMAL / S TATISTICAL A NALYSIS An extensive study of the thermal behavior of the instrument has been done (2006)An extensive study of the thermal behavior of the instrument has been done (2006) A set of 5360 averages of “Deep Space” and “Internal Black-Body” measurements has been collected, monitoring T D, T BB and T IB.A set of 5360 averages of “Deep Space” and “Internal Black-Body” measurements has been collected, monitoring T D, T BB and T IB. The main "expected" results are: 1)As already found in laboratory, the instrumental thermal emission is mainly controlled by the detector temperature; 2)as a consequence of point 1), the measured signal depends on the detector temperature; 3)This dependence on the detector temperature is linear and, knowing the detector temperature, we have the instrumental thermal emission by interpolation; This study also shows some other interesting results: a)The mechanical vibrations affect also the LW channel spectra; b.they cause systematic statistical errors in the measured signal of the same order of magnitude of the variations due to the detector temperature changes. In other words, even at thermal regime conditions ( T D ~287.0 K), a stable source (i.e. DS) shows variations of ~ 5-7% of the signal; c.Interesting enough, this systematic statistical errors have a ZERO- AVERAGE VALUE: averaging independent sets of Deep-Space spectra (at a given detector temperature) we get identical averages. FWD REV MEx and VEx DATA WORKSHOP - PFS and SOIR experiments - 27 June - 1st July 2011, ESA/ESAC,Spain

5 More than 90% of the Martian data and 99% of the Deep-Space measurements are acquired with the detector temperature well stable at ~287.0 K; consequently, thanks to point c), averaging all the DS measurements we have a very accurate estimate of the thermal emission of the instrument at thermal regime condition (i.e. for than 90% of the data) -> better radiometric calibration;More than 90% of the Martian data and 99% of the Deep-Space measurements are acquired with the detector temperature well stable at ~287.0 K; consequently, thanks to point c), averaging all the DS measurements we have a very accurate estimate of the thermal emission of the instrument at thermal regime condition (i.e. for than 90% of the data) -> better radiometric calibration; Thanks to point 3), we have a very accurate estimate of the thermal emission of the instrument also for non-regime conditions -> better radiometric calibration;Thanks to point 3), we have a very accurate estimate of the thermal emission of the instrument also for non-regime conditions -> better radiometric calibration; we don't need to use the calibration measurements within each session to have the instrumental thermal emission and responsivity. ALL orbits can now be calibrated!we don't need to use the calibration measurements within each session to have the instrumental thermal emission and responsivity. ALL orbits can now be calibrated! The residuals (artifacts, slopes etc...) sometimes present in the LWC spectra, will be reduced but will STILL be present, since they are NOT ONLY due to changes in the thermal conditions of the instrument, but also to the external mechanical vibrations and the two effects are of the same order of magnitude.The residuals (artifacts, slopes etc...) sometimes present in the LWC spectra, will be reduced but will STILL be present, since they are NOT ONLY due to changes in the thermal conditions of the instrument, but also to the external mechanical vibrations and the two effects are of the same order of magnitude. C ALIB_ V4 From the previous analysis follows that: MEx and VEx DATA WORKSHOP - PFS and SOIR experiments - 27 June - 1st July 2011, ESA/ESAC,Spain


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