1. Page 1 SAOZ EUREKA Feb-Mar 05 Post campaign Meeting - Eureka 2005,- 30 May 2005 Outline Objectives Results Florence Goutail Service d’Aeronomie / CNRS, France SAOZ at Eureka

2. Page 2 SAOZ EUREKA Feb-Mar 05 Post campaign Meeting - Eureka 2005,- 30 May 2005 OBJECTIVES Ozone and NO2 monitoring  O3, NO2 Slant columns - One reference spectrum for the whole campaign  Converted  Vertical columns - Using an Arctic winter AMF (from SAOZ balloon profile at 67 °N) - SZA selection: 86 - 91 ° Ozone loss during winter 2004/05 Using REPROBUS and/or SLIMCAT 3D CTM

3. Page 3 SAOZ EUREKA Feb-Mar 05 Post campaign Meeting - Eureka 2005,- 30 May 2005 Instrument Ground-based SAOZ UV-Visible spectrometerlooking at zenith (270 -620 nm, 1nm resolution) Columns: O3, NO2, ( Color index - clouds)

4. Page 4 SAOZ EUREKA Feb-Mar 05 Post campaign Meeting - Eureka 2005,- 30 May 2005 O3 and NO2 AMF

5. Page 5 SAOZ EUREKA Feb-Mar 05 Post campaign Meeting - Eureka 2005,- 30 May 2005 O3 and NO2 vertical columns Ozone: -Large day to day variations -Between day 55 and day 72 difference between morning and evening why? NO2: After day 69, more sunlight, NO2 is increasing and diurnal variation is observed

6. Page 6 SAOZ EUREKA Feb-Mar 05 Post campaign Meeting - Eureka 2005,- 30 May 2005 Why O3 sunset larger than O3 sunrise ? One explanation could be because Eureka is located at the edge of the vortex. Here is a map of PV at 475K (by Mimosa contour advection model) yellow inside vortex and red outside. Eureka is represented by blue star Mimosa: A. Hauchecorne, CNRS/SA

7. Page 7 SAOZ EUREKA Feb-Mar 05 Post campaign Meeting - Eureka 2005,- 30 May 2005 Why O3 sunset larger than O3 sunrise ? As an example: On day 69, March 10, 2005 O3sr = 364 DU O3ss = 439 DU Sunrise: SAOZ is looking toward east that is inside vortex Sunset: SAOZ is looking toward west that is outside vortex

8. Page 8 SAOZ EUREKA Feb-Mar 05 Post campaign Meeting - Eureka 2005,- 30 May 2005 Ozone loss during Arctic winter Method: Difference between measurements and passive ozone from a 3D CTM in which ozone is considered as a passive tracer Model 3D CTM (chemical transport model): Reprobus (F. Lefevre) Slimcat (M. Chipperfield, W Feng)

9. Page 9 SAOZ EUREKA Feb-Mar 05 Post campaign Meeting - Eureka 2005,- 30 May 2005 Ozone loss above Eureka - Slimcat 3D CTM correctly reproduces day to day variations -A large difference is observed between transported passive Ozone (black) and SAOZ (pink): it is attributed to chemical loss. At the end of winter the difference reach 135 DU= ~25%

10. Page 10 SAOZ EUREKA Feb-Mar 05 Post campaign Meeting - Eureka 2005,- 30 May 2005 Zhigansk (CNRS/CAO) Salekhard (CNRS/CAO) Sodankyla (CNRS/FMI) Harestua (BIRA) NyAlesund (NILU) Thule (DMI) ScoresbySund (CNRS/DMI) Zhigansk (CNRS/CAO) Salekhard (CNRS/CAO) Sodankyla (CNRS/FMI) Harestua (BIRA) NyAlesund (NILU) Thule (DMI) ScoresbySund (CNRS/DMI) Comparison to other SAOZ Arctic stations Eureka (Canada) Measurements and associated model data are selected only when the station is located inside vortex.

11. Page 11 SAOZ EUREKA Feb-Mar 05 Post campaign Meeting - Eureka 2005,- 30 May 2005 Comparison to other SAOZ stations -Loss above Eureka (green) seems similar to that of other Stations -Cumulative loss at the end of winter: 25% according to Slimcat -with REPROBUS 3D CTM 22%

12. Page 12 SAOZ EUREKA Feb-Mar 05 Post campaign Meeting - Eureka 2005,- 30 May 2005 Conclusion Ozone and NO2 morning and evening vertical columns recorded for the whole campaign. Ozone loss during winter 2004/05 above SAOZ stations 25% at Eureka: 25% -> 135 DU