1. Simulating the atmospheric composition during the last decades: Evaluation with long-term observational datasets and the impact of natural climate variability Volker Grewe, Martin Dameris, Jens Grenzhäuser and Pieter Valks German Aerospace Center ACCENT-GLOREAM, Paris, October, 2006

2. Institut für Physik der Atmosphäre 28.03.2006 Institutstag IPA 2006 Transport and Chemistry NOx - Ozon Production Ozone Production (Chapman ) Ozone Intrusion ENSO Solar Cycle Air Quality Emissions

3. Institut für Physik der Atmosphäre 28.03.2006 Institutstag IPA 2006 CCM E39/C (Stratosphere-troposphere)- Model description Surface, aircraft, lightning NO x Emissions [Tg N/a] Radiation Long-wave Short-wave Chemical Boundary Conditions Atmosphere: CFCs, at 10 hPa: ClX, NO y, Surface: CH 4, CO Chemistry (CHEM) Methane oxidation Heterogeneous Cl reactions PSC I, II, aerosols Dry/wet deposition Photolysis Feedback O 3, H 2 O, CH 4, N 2 O, CFCs Prognostic variables (vorticity, divergence, temperature, specific humidity, log-surface pressure, cloud water), hydrological cycle, diffusion, gravity wave drag, transport of tracers, soil model, boundary layer; sea surface temperatures. T30, 39 layers, top layer centred at 10 hPa Dynamics (ECHAM) Hein et al., 2001

4. Institut für Physik der Atmosphäre 28.03.2006 Institutstag IPA 2006 Transiente Model simulation - Boundary Conditions QBO Solar cycle and volcanoes Dameris et al., 2005

5. Institut für Physik der Atmosphäre 28.03.2006 Institutstag IPA 2006 Transiente Model simulation - Boundary Conditions Natural und anthropogenic NO x emissions: SourceReference Emissions: 1960 to 2000 IndustryBenkovitz et al., 1996 12 - 33 TgN/a Lightning Grewe et al., 2001 ~5 TgN/a Air trafficSchmitt und Brunner, 97 0.1 - 0.7 TgN/a Surface Traffic Matthes, 2003 3.6 - 9.9 TgN/a ShipsCorbett et al, 1999 1.2 - 3.2 TgN/a Biomass BurningLee, pers. comm 6.3 - 7.2 TgN/a Sea surface temperatures and ice coverage: Monthly means: UK Met Office Hadley Centre, hier: Beispiel für Juni 1985 (Rayner et al., 2003)

6. Institut für Physik der Atmosphäre 28.03.2006 Institutstag IPA 2006 Evolution of ozone column [DU]: 1960 - 2000 196 0 200 0 198 0 Ozone hole High variability

7. Institut für Physik der Atmosphäre 28.03.2006 Institutstag IPA 2006 De-seasonalized anomalies of the ozone columns [%] +++++ ---- QBO clearly visible Global Trend: ~20 DU 196 0 200 0 198 0 11y- Solar cycle recognizable, but QBO, volcanoes, trend overlaid

8. Institut für Physik der Atmosphäre 28.03.2006 Institutstag IPA 2006 E39/C vs. Observation: Anomalies of ozone column E39/C TOMS Ground stations (Bojkov and Fioletov, 1995; pers. com. Fioletov, 2004) calm, stable winter situations Beginning of 90s: stronger ozone losses Individual strong events well represented

9. Institut für Physik der Atmosphäre Validation of E39C results: Tropospheric Ozone Mean annual cycle of ozone at 47°N, 11°E (1967-2000) E39C OBS E39C minus OBS Hohenpeißenberg Too weak seasonal cycle Cold bias too = high tropopause

10. Institut für Physik der Atmosphäre Validation of E39C results Mean annual cycle of ozone at 40°N, 105°W (1979-2000) E39C OBS E39C minus OBS Boulder Similar conclusion

11. Institut für Physik der Atmosphäre Validation of E39C results 47°N, 11°E; 300 hPa 47°N, 11°E; 500 hPa 47°N, 11°E; 700 hPa 47°N, 11°E; 850 hPa Ozonesonde E39C Ozonesonde E39C Ozonesonde E39C Ozonesonde E39C Evolution of ozone anomalies at distinct levels [in ppbv] Hohenpeißenberg Variability smaller: Sampling or real difference ? Evolution not well reproduced: - very rough assumptions on emission data - no interannual variability of bb emissions

12. Institut für Physik der Atmosphäre Validation of E39C results 47°N, 11°E; 500 hPa Ozonesonde E39C Evolution of ozone anomalies [in ppbv] Some agreement: Coincidience or period where changes are controll by processes, which are better described

13. Institut für Physik der Atmosphäre April Average tropospheric tropiocal O 3 -Column below 200 hPa 1996-2003 July October Januar 180°W 20°N Eq. 180°E 20°S Generally higher ozone values ! General pattern in agreement: Minimum over Pacific Maximum over Africa GOME (TEMIS)E39/C However, ozone maximum less pronounced: Biomass burning?

14. Institut für Physik der Atmosphäre Average tropospheric tropiocal O 3 -Column below 200 hPa 1996-2003 Generally higher ozone values ! General pattern in agreement: Minimum over Pacific Maximum over Africa GOME (TEMIS)E39/C However, ozone maximum less pronounced: Biomass burning? 180°W 20°N Eq. 180°E 20°S MAM DJF JJA SON 15-40 DU 10-30 DU Minimum South America Maximum Africa Minimum Pacific

15. Institut für Physik der Atmosphäre How can we understand the simulated trends and the observed differences ? - Sensitivity studies (for selected periods) e.g. rerun period without volcanic eruption (Pinatubo) - Additional diagnostics Tracer: Ozone origin (Regions in Stratosphere/ Troposphere) Tracer: Ozone 'source') (biomass burning, Lightning,...) Mass fluxes

16. Institut für Physik der Atmosphäre 28.03.2006 Institutstag IPA 2006 Simulated ozone origin Grewe, 2006

17. Institut für Physik der Atmosphäre 28.03.2006 Institutstag IPA 2006 Grewe, 2004

18. Institut für Physik der Atmosphäre 28.03.2006 Institutstag IPA 2006 Ozone influx from the stratosphere to the troposphere De-seasonalized Monthly means x Estimate based on correlations with long-lived species: 475 Tg/year (Murphey and Fahey, 1994) and with flux calculations: NH: 252 Tg/a SH: 248 Tg/a (Olson et al., 2004) Signal of solar cycle identifyable especially on SH Large interannual variability No trends recognizable + - + - + - + - +

19. Institut für Physik der Atmosphäre 28.03.2006 Institutstag IPA 2006 De-seasonalized ozone changes in the tropical UT Stratospheric ozone follows influx from stratosphere, producing ±2% variability out of a totale interannual var. of ±4% Lightning ozone correlated with Nino Index variability: ±1-2%

20. Institut für Physik der Atmosphäre 28.03.2006 Institutstag IPA 2006 Evolution of de-seasonalized ozone in NH lower troposphere (30N-90N; 500-1000 hPa) Year-to-year variability strongly dominated by stratosphere (±5%) Trend in ozone (25% increase): - results from increase in NO x emissions (Industry and traffic) - Trend reduction in 80s caused by lower emissions and lower stratospheric contribution. ~25% ~30% -5%

21. Institut für Physik der Atmosphäre Conclusions - Outlook (I) Stratosphere well reproduced Troposphere: Some similarities with observational data Main Discrepancies: Too weak seasonal cycle: - Too strong influence from stratosphere (chem lifetime) - Too much transport of upper troposphere tropical air - Too weak seasonal cycle of O 3 perturbation from anthropogenic emissions Less intense tropical ozone maximum Solution: Rerun with revised emission data (RETRO) biomass burning + anthrop. emission data including interannual and regional variability

22. Institut für Physik der Atmosphäre Conclusions - Outlook (II) Discrepancies: Less ozone in the upper troposphere: - Problem of cold bias = too high tropopause Solution: Lagrangian transport scheme Realistic water vapor transport 80% Reduction of Cold Bias (Stenke&Grewe, 2006) Despite discrepancies Stratospheric ozone variability influences trend (Trend reduction in 80s) Impact of stratospheric and tropospheric variability (El Nino) quantified.

23. Institut für Physik der Atmosphäre

24. Institut für Physik der Atmosphäre Future outlook adopted from Fishman et al., 2003

25. Institut für Physik der Atmosphäre JanFebMar AprMayJun JulAug Dec Sep NovOct GOME (CCD): Average O 3 -Column below 200 hPa 1996-2003 180°W 20°N Eq. 180°E 20°S

26. Institut für Physik der Atmosphäre E39C : Average tropospheric O 3 -column 1992-1999 JanFebMar AprMayJun JulAug Dec Sep NovOct 20°N Eq. 180°W180°E 20°S

27. Institut für Physik der Atmosphäre 28.03.2006 Institutstag IPA 2006 Total cloud cover from the transient run of the ECHAM model in comparison to ISCCP, ECC, and SYNOP data sets ECC, ~11:30-16:30 UT ISCCP-D2, 12:00 UT SYNOP, 12:00 UT ECHAM, 24h Monthly means, area averaged d=+12% c=0.2 d=-16% c=0.7 d=0.0% c=0.4 R. Meerkötter, V. Grewe, M.Dameris, M. Ponater; (DLR-IPA), H. Mannstein (DLR-IPA), G. Gesell (DLR-DFD), C.König (DLR-IPA) Meerkötter et al., 2004

28. Institut für Physik der Atmosphäre Validation of E39C results Mean annual cycle of ozone at 13°S, 171°W (1987-2000) E39C OBS E39C minus OBS Samoa

29. Institut für Physik der Atmosphäre Validation of E39C results Mean annual cycle of ozone at 70°S, 8°W (1992-2000) E39C OBS E39C minus OBS Neumayer

30. Institut für Physik der Atmosphäre Validation of E39C results 47°N, 11°E; 500 hPa Ozonesonde E39C Ozonesonde E39C 40°N, 105°W; 500 hPa Evolution of ozone anomalies at distinct stations [in ppbv] Hohenpeißenberg Boulder

31. Institut für Physik der Atmosphäre 28.03.2006 Institutstag IPA 2006 Ozone influx: ozone origin Northern Hemisphere: Ozone mainly produced in NHMS TRMS TRTS NHMS: high inter-annual variability Southern Hemisphere: Ozone mainly produced in TRTS SHMS TRLS SHMS low inter-annual variability solar cycle visible Grewe, 2005