1. Page 1 GOMOS Calibration Review - ESTEC - 10 September 2002 GOMOS Level 2 processing Verification activities Comparison with external sources ESTEC – SEPTEMBER 10, 2002 Level 2 session Alain Hauchecorne, Marielle Guirlet, Erkki Kyrölä, Johanna Tamminen, Antoine Mangin, Odile Fanton d’Andon

2. Page 2 GOMOS Calibration Review - ESTEC - 10 September 2002 GOMOS O3 vertical profiles: first attempts of validation Comparisons of GOMOS O3 vertical profiles with: HALOE, POAM, lidar Objectives: Systematic bias with star ? Latitude ? Dark/Bright limb Deficiencies of processing ?

3. Page 3 GOMOS Calibration Review - ESTEC - 10 September 2002 Courtesy HALOE data C. Jackman, L. Deaver, J.R. Russell

4. Page 4 GOMOS Calibration Review - ESTEC - 10 September 2002 Courtesy HALOE data C. Jackman, L. Deaver J.R. Russell

5. Page 5 GOMOS Calibration Review - ESTEC - 10 September 2002 Courtesy HALOE data C. Jackman, L. Deaver, J.R. Russell

6. Page 6 GOMOS Calibration Review - ESTEC - 10 September 2002 Courtesy HALOE data C. Jackman, L. Deaver, J.R. Russell

7. Page 7 GOMOS Calibration Review - ESTEC - 10 September 2002 Courtesy HALOE data C. Jackman, L. Deaver, J.R. Russell

8. Page 8 GOMOS Calibration Review - ESTEC - 10 September 2002 Courtesy HALOE data C. Jackman, L. Deaver, J.R. Russell

9. Page 9 GOMOS Calibration Review - ESTEC - 10 September 2002 Courtesy POAM data R. Bevilacqua

10. Page 10 GOMOS Calibration Review - ESTEC - 10 September 2002 Courtesy POAM data R. Bevilacqua

11. Page 11 GOMOS Calibration Review - ESTEC - 10 September 2002 Courtesy lidar data A. Hauchecorne, S. Godin

12. Page 12 GOMOS Calibration Review - ESTEC - 10 September 2002 Early start of the validation phase R00799/S081 First GOMOS-external ozone local (lidar – OHP) profile comparison, Currently under investigation at Service d’Aéronomie (Alain Hauchecorne) Measurements separated by less than 250 km And by 2 hours Mv=2.36, T=28000K Courtesy lidar data A. Hauchecorne, S. Godin

13. Page 13 GOMOS Calibration Review - ESTEC - 10 September 2002 Courtesy lidar data A. Hauchecorne, S. Godin

14. Page 14 GOMOS Calibration Review - ESTEC - 10 September 2002  Short-scale features rather well captured for some profiles  Need of a larger number of measurements for more systematic studies: variation with latitude variation with distance variation with season  Use of averaging kernels  Support from assimilation tools Conclusions and perspectives