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Recalibrated Ozone Profiles from GOME-UV/Vis Nadir spectra

ERS-ENVISAT Symposium, Salzburg, 6-10 Sep 2004. Recalibrated Ozone Profiles from GOME-UV/Vis Nadir spectra. Silvia Tellmann, Mark Weber , Vladimir Rozanov, and John Burrows Institute of Environmental Physics/ Institute of Remote Sensing University of Bremen. Overview.

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Recalibrated Ozone Profiles from GOME-UV/Vis Nadir spectra

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  1. ERS-ENVISAT Symposium, Salzburg, 6-10 Sep 2004 Recalibrated Ozone Profiles from GOME-UV/Vis Nadir spectra • Silvia Tellmann, Mark Weber, Vladimir Rozanov, • and John Burrows • Institute of Environmental Physics/ • Institute of Remote Sensing • University of Bremen

  2. Overview • O3 nadir profiling in Bremen • Calibration Problems in FURM V5 • Improved calibration correction • low latitude approach • global approach • Improved tropospheric retrieval • Conclusion

  3. GOME O3 profile retrieval in Bremen • Full Retrieval Method (FURM): • Optimal estimation and Kozlov information matrix approach & validation with ozone sonde data • R. Hoogen, V.V. Rozanov, J.P. Burrows, Ozone Profiles from GOME Satellite Data: Algorithm Description and First Validation, J. Geophys. Res., 104, 8263-8280, 1999. • R. Hoogen, V.V. Rozanov, K. Bramstedt, K.-U. Eichmann, M. Weber, and J.P. Burrows, Ozone profiles from GOME satellite data-I: Comparison with ozonesonde measurements, Physics and Chemistry of the Earth 24, 447-452, 1999. • Extensive validation of Version 5 with lidar and satellite data • K. Bramstedt, K.-U. Eichmann, M. Weber, V. Rozanov, and J. P. Burrows, GOME ozone profiles: A global validation with HALOE measurements, Adv. Space Res. 29, 1637-1642, 2002. • K. Bramstedt, J. Gleason, D. Loyola, W. Thomas, A. Bracher, M. Weber, and J. P. Burrows, Comparison of total ozone from the satellite instruments GOME and TOMS with measurements from the Dobson network 1996-2000, Atmospheric Chemistry and Physics 3, 1409-1419, 2003. • G. Hansen, K. Bramstedt, V. Rozanov, M. Weber, and J.P. Burrows, Validation of GOME ozone profiles by means of the ALOMAR ozone lidar, Annales Geophysicae 21, 1879-1886, 2003. • A. Bracher, M. Weber, K. Bramstedt, S. Tellmann, J. P. Burrows, Long-term global measurements of ozone profiles by GOME validated with SAGE II considering atmospheric dynamics, J. Geophys. Res., accepted, 2004.

  4. GOMEO3 profile retrieval in Bremen (II) • Application in scientific studies: Arctic ozone depletion, international field campaigns (OFP, THESEO2000), ozone miniholes • K.-U. Eichmann, K. Bramstedt, M. Weber, R. Hoogen, V.V. Rozanov, and J.P. Burrows, Structure of ozone mini-holes from GOME, European Symposium on Atmospheric Measurements from Space, Proc. ESAMS'99, ESA-WPP-161, 231-236, 1999. • K.-U. Eichmann, K. Bramstedt, M. Weber, V.V. Rozanov, R. Hoogen and J.P. Burrows, O3 profiles from GOME satellite data - II: Observations in the Arctic spring 1997 and 1998, Physics and Chemistry of the Earth 24, 453-457, 1999. • H. Bremer, M. von König, A. Kleinböhl, H. Küllmann, K. Künzi, K. Bramstedt, J. P. Burrows, K.-U. Eichmann, M. Weber, A. P. H. Goede, Ozone depletion observed by ASUR during the Arctic Winter 1999/2000, J. Geophys. Res. 107, 8277, doi:10.1029/2001JD000546, 2002. • K.-U. Eichmann, M. Weber, K. Bramstedt, and J.P. Burrows, Ozone depletion in the NH winter/spring 1999/2000 as measured by GOME-ERS2, J. Geophys. Res. 107, 8280, doi:10.1029/2001JD001148, 2002. • U. Klein, I. Wohltmann, K. Lindner, and K. F. Künzi, Ozone depletion and chlorine activation in the Arctic winter 1999/2000 observed in Ny-Ålesund, J. Geophys. Res., 107 (D20), 8288, doi:10.1029/2001JD000543, 2002. • Continued development: tropical retrieval (wavelength extension) and cloud/albedo effects, a-priori profile sensitivity • S. Tellmann, S., V.V. Rozanov, M. Weber, and J.P. Burrows, Improvements in the tropical ozone profile retrieval from GOME UV/vis nadir spectra, Adv. Space Res. 34, 739-743, 2004. • L. N. Lamsal, M. Weber, S. Tellmann, and J. P. Burrows, Ozone column classified climatology of ozone and temperature profiles based on ozonesonde and satellite data, J. Geophys. Res., accepted, 2004.

  5. FURM inversion scheme O3-eigenvectors in altitude range • calculate ozone on several altitude levels large number of parameters: n  70 • Develop the profile in a sum of eigenfunctions with proper truncation  n  10 • Kozlov-Information-matrix-method combined with optimal estimation: altitude [km] O3-EV [-] O3-eigenvectors in wavelength range O3-EV [-] Wavelength [nm]

  6. Radiometric calibration problems dichroic mirror degradation ratio of GOME solar spectra direct after launch and 5 years later 1.0 Ratio [-] 0.8 etalon 0.6 0.4 600 400 800 240 Wavelength [nm] • outgassing (mainly optical coatings e. g. dichroic mirror) change optical features • etalon structures: contamination layers on cooled detectors (ice) varies in time  spectral modulation • UV degradation of the instrument: scan mirror is exposed to UV-radiation • polarization degradation

  7. FURM V5 empirical calibration Chebychev Polynomials 0.1 • wavelength range: 290 – 340 nm • broadband calibration correction to • allow for UVdegradation • Chebychev Polynomials polynomials [-] -0.1 -0.3 340 320 280 300 wavelength [nm] Deviations between model and measurement 0.4 Channel 1 • differential corrections: • NOT applied !!!! •  V5 restricted to wavelengths 0.2 residual [-] 0.0 -0.2 310 290 300 280 wavelength [nm]

  8. Shortcomings in FURM V5 • lack of information in upper stratosphere (above 35-40 km) • problems in tropics where ozone maximum is shifted to • higher altitudes • wavelengths below 290 nm needed to enhance stratospheric • information content • Chebyshev polynomials inadequate at short wavelengths ozone profiles in tropics measurement sensitivity Sensitive to measurement 50 FURM SAGEII Climatology 60 40 40 Altitude [km] Altitude [km] 30 20 20 0 0.6 1.0 1.4 0.2 O3-concentration Sum of rows AK-Matrix [-]

  9. Tropical calibration correction • large differential structures • below 290 nm • strong filling-in of • Fraunhofer lines Differential sunnormalized radiance 5D-4 GOME Model 3D-4 y_meas [-] 1D-4 -1D-4 290 280 285 275 residual & fit of diff. error wavelength [nm] GOME - Model 5D-4 Diff. error • New corrections by differential fit: • Fit addition error term: a ~1/irradiance • 1/irr & polynomial fit before ozone retrieval (prefit in Ch. 1) 3D-4 y_meas – y_model [-] 1D-4 -1D-4 285 290 275 280 wavelength [nm]

  10. High latitude calibration correction  Ozone maximum in middle and high latitudes shifted to lower altitudes and longer wavelengths  low differential structure of ozone absorption strong correlations between broadband calibration  corrections and atmospheric parameter  change of broadband calibration correction required below 300 nm statistical investigation of residuals Mean residuals 1997-2003 in comparison with HALOE 1.0 0.8 0.6 Residual [-] 0.4 0.2 0.0 300 275 280 295 285 290 wavelength [nm]

  11. Results from 1997 Relative deviations between standard version/new version and independent measurement from SAGE II (Stratospheric Aerosol and Gas Experiment II) old results Comparison of O3 [ppm] SAGE/FURM 50 50 0.3 Rel. Deviations New Old New 40 0.2 40 30 Altitude [km] 20 0.1 altitude [km] 30 new results 50 0.0 tropics Rel. Deviations Old 40 20 Altitude [km] -0.1 30 -0.2 10 20 0.4 0.6 0.0 -0.6 -0.4 -0.2 0.2 -40 -60 60 -20 0 20 40 2(SAGE-GOME)/(SAGE+GOME) -0.3 latitude [deg]

  12. Results from 2003 Relative deviations between SAGE II and FURM old results New Results Comparison of O3 [ppm] SAGE/FURM 0.3 50 50 Old New 0.2 40 45 Altitude [km] 30 40 0.1 20 35 altitude [km] No of Pixel 0.0 30 new results 50 25 -0.1 40 20 Altitude [km] 30 -0.2 15 -0.4 -0.2 0.0 0.2 0.4 0.6 -0.6 20 2(SAGE-GOME)/(SAGE+GOME) -0.3 No of Pixel 20 60 -40 -60 -20 0 40 latitude [deg]

  13. Tropospheric retrieval Ozone Profile Hohenpeissenberg 50 FURM Sonde Climatology Aks for retrieval levels in troposphere 40 50 30 40 altitude [km] 20 30 altitude [km] 10 20 0 O3 Conc 10 retrieved tropospheric ozone always quite near to climatological values averaging kernels (AKs) indicate where information in retrieved height level comes from 0 Averaging Kernels [-]

  14. Tropospherical investigations • Profile fit: spectral window too large to make accurate tropospheric ozone fit • Use just channel 2 to improve tropospheric column fit • Two step retrieval: • Common ozone profile fit to get information about • stratospheric constituents. • 2. Use fitted profile and investigate residual in channel 2 • (~320-335 nm) troposphere here defined up to ECMWF thermal tropopause • Make new diff. fit of tropospherical ozone column, • temperature and Ring (inelastic scattering)

  15. Sensitivity in Channel 2 0.04 Residual & Fit 0.00 Residual Residual [-] Fit all param. -0.04 Trop. Col. 0.02 O3 WF fit [-] New col. 0.00 Old col. -0.02 0.002 Temp. Fit 0.000 T WF fit [-] -0.002 0.02 Ring Fit Ring WF fit [-] 0.00 -0.02 324 332 320 322 330 334 326 328 wavelength [nm]

  16. Tropospherical Column Results Relative Deviations between O3–Sonde and climatology as well as FURM Hohenpeissenberg 1997 + troposph. columns from profile retrieval troposph. columns from differential fit in channel 2 regression line for profile fit regression line for step 2 differential fit in channel 2 Rel. deviations Sonde-FURM [-] • in most cases improvements • for very small differences • to climatological value • instabilities in differential fit (noise) Rel. deviations Sonde-Climatology [-]

  17. Conclusions  Stratospheric information content can be enhanced by combined calibration concept in short wavelength region using • differential „dark current“ approach for tropics/southern anomaly • residual fit for middle and high latitudes.  Tropospheric retrieval based upon two step approach • accurate stratospheric ozone fit • accurate fit of Ring & atm. Parameters • realistic climatological ozone profile form • Inclusion of new ozone a-priori climatology (Lamsal et al. 2004) • Reprocessing of GOME 1995-2003 in preparation (funding?) • First application to SCIAMACHY (Version 5)

  18. A-priori profile sensitivity  IUP climatology (Lamsal et al., JGR, 2004) • F&K (Fortuin and Kelder, JGR, 1998) • Improvement in the lowermost stratosphere with IUP climatology • see also talk by Lamsal et al. (Abstract 353) for details on IUP O3 climatology Hohenpeissenberg 1997 23 August 2002

  19. SCIAMACHY nadir application  limb retrieval V1.6 (Savigny et al., JAS, 2004) • FURM nadir retrieval Version 5 • there are still outstanding issues regarding calibration • Visit poster by Bramstedt et al. (3P08-6) for more details 23 August 2002

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