1. Limb Retrieval at IFE/IUP in Bremen Working team: A. Rozanov, K.-U. Eichmann, C. v. Savigny, J. Kaiser Tests based on level 0 data Normalisation by –Solar irradiance –Radiance at reference tangent height

2. Raw Limb Spectra  Only uncalibrated readouts available to date (top plots)  Division by integration time yields counts/sec  Dark current corrected by subtracting highest tangent height  Dead/bad pixels omitted  Normalization to reference tangent height removes solar and instrumental features. (bottom plots)  Recorded April 25  Tangent heights:  -2, 1, 4,...97 km (Klick on plot for enlargement)

3. Spectra Channels 1 & 2

4. Spectra Channels 3 & 4

5. Spectra Channels 5 & 6

6. Spectra Channels 7 & 8

7. Two Radiative Transfer Models Requirements UV-VIS- SWIR RTM Limb SCIATRAN/CDIPI (A. Rozanov 2001) SCIARAYS (Kaiser 2001) Refraction Full Sphericity Multiple Scattering  (two orders) Ground Reflection Rayleigh, Mie-Scattering Analytical Weighting Functions  (trace gases) Computational fast for global analysis of data  Occultation included

8. 8 O 3 profile retrieval by normalization and wavelength pairing [Flittner et al. 1999] : Use uncalibrated limb radiance profiles in the centre (600 nm) and the wings (530 nm, 670 nm) of the O 3 Chappuis absorption bands Normalization by limb radiance at 50 km tangent height Wavelength pairing Use Optimal Estimation and a multiple scattering model to iteratively retrieve Ozone profiles Retrieval Algorithm I: Wavelength Triplet

9. 9 Lat: 5° N Long: 135° W SZA = 30°  = 110° 10 – 50 km O 3 column: 256 DU GOME total column: 253 DU EP-TOMS total column: 264 DU April 25, 2002, Orbit 797, Limb scan 19 Algo I: Sample O 3 profile retrieval PRELIMINARY RESULTS!!!

10. Algo II: Differential Retrieval Normalization to solar irradiance spectrum Subtraction of polynomials Spectral range: 312 – 345 nm Tangent heights: 16 – 70 km Different geolocation: 60 deg N Radiative Transfer with SCIATRAN/CDI Inversion with iterative Tikhonov method

11. Algo II: Sample O 3 profile retrieval PRELIMINARY RESULTS!!!

12. Algo III: Normalized differential Retrieval Use spectral range –500 – 590 nm (channel 3) for O3 retrieval –420 – 460 nm (channel 3) for NO2 retrieval Normalization to successive radiance spectrum Subtraction of polynomials Radiative Transfer with SCIARAYS Inversion with iterative optimal estimation

13. Algo III: Sample O 3 profile retrieval PRELIMINARY RESULTS!!!

14. Algo III: Sample NO 2 profile retrieval Order of magnitude correct.

15. Ch 1, signal

16. Ch 2, signal

17. Ch 3, signal

18. Ch 4, signal

19. Ch 5, signal

20. Ch 6, signal

21. Ch 7, signal

22. Ch 8, signal

23. Ch 1, fractions

24. Ch 2, fractions

25. Ch 3, fractions

26. Ch 4, fractions

27. Ch 5, fractions

28. Ch 6, fractions

29. Ch 7, fractions

30. Ch 8, fractions