Climate-Chemistry Interactions - User Requirements

1. Climate-Chemistry Interactions -User Requirements Martin Dameris DLR-Institut für Physik der Atmosphäre Oberpfaffenhofen

2. Modelling of climate-chemistry interactions - Why? • Climate change detected (e.g. IPCC, 2001). • Changes in atmospheric composition observed (e.g. WMO, 2003). • Coupling of chemical processes in climate models. • Climate-Chemistry Models (CCMs) have been employed to examine the feedback between dynamical, physical and chemical processes.

3. Modelling of climate-chemistry interactions - Why? • The primary goals of CCMs are to • support analyses of (long-term) observations of trace gases and aerosols, • evaluate emission control measures, • determine and quantify underlying dynamical, physical and chemical processes, and their feedback, • explain recent changes (variability), • assess possible future trends.

4. Modelling of climate-chemistry interactions - scientific applications or problems • Tropospheric air quality (chemical weather). • The effect of surface pollution (including traffic), aviation and natural factors on chemical, radiative and dynamical (e.g. long-range transport) processes in the upper troposphere and stratosphere. • How do climate change impact atmospheric chemistry (composition) and vice versa? • A key science issue is to determine the timing of ozone recovery and future ultraviolet radiation at the surface.

5. Development of CCMs - general progress in recent years • about 15 years ago • first coupling of climate models (GCMs) to simplified chemistry (e.g. Cariolle et al., 1990). • about 7 years ago • off-line climate-chemistry models (CCMs) with complex chemistry (e.g. Steil et al., 1998); • first results regarding ozone recovery (e.g. Dameris et al.,1998; Shindell et al., 1998). • today • interactively coupled CCMs available (e.g. Hein et al., 2001); • investigations of feedback between dynamical, physical, and chemical processes (e.g. Schnadt et al., 2002; Austin et al., 2003).

6. NOx Emissions [Tg N/a] Surface, aircraft, lightning Photolysis Dynamics (ECHAM) T30, 39 layers, top layer centred at 10 hPa Chemistry (CHEM) 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. Methane oxidation Heterogeneous Cl reactions PSC I, II, aerosols Dry/wet deposition Feedback O3, H2O, CH4, N2O, CFCs Chemical Boundary Conditions Radiation Atmosphere: CFCs, at 10 hPa: ClX, NOy, Surface: CH4, CO Long-wave Short-wave The CCM E39/C - Description of model system Hein et al., 2001

7. Application of CCMs for process studies • Investigation of • chemical composition and climate variability (change), • tropospheric and stratospheric coupling, • especially in order to determine and quantify feedback processes.

8. Comparison - E39/C vs. MSU: temperature anomalies (1979-1990), 13-21 km, global mean

9. E39/C NCEP Type I PSC Type II PSC E19/C Type I PSC Comparison - E39/C vs. NCEP analysis: zonal mean temperature (80°N, 30 hPa) Hein et al., 2001

10. E39/C NCEP E19/C Comparison - E39/C vs. NCEP analysis: zonal mean wind (60°N, 30 hPa) Hein et al., 2001

11. Comparison - E39/C vs. GOME: ozone columns [in DU] Gome data provided by DLR-DFD, Dr. M. Bittner

12. -4 -26 -6 -24 Comparison - E39/C vs. ground based and TOMS-data: climatological mean values of total ozone and “trends” 1990 1990 - 1980 Model Latitude Observations McPeters et al., 1996 Hein et al., 2001; Schnadt et al., 2002

13. GOME (1996 - 2000) E39/C (1990) Comparison - E39/C vs. GOME: NO2 tropospheric columns (July) Lauer et al., 2001; GOME-data provided by IUP, A. Richter and J. Burrows

14. Comparison - E39/C vs. GOME: NO2 tropospheric columns, annual cycle over Africa ECHAM4/CHEM ECHAM4/CBM (G.-J. Roelofs, Utrecht) GOME Lauer et al., 2001; Matthes, 2003

15. Comparison - E39/C vs. GOME: NO2 tropospheric columns, annual cycle over Africa and Europe ECHAM4/CHEM ECHAM4/CBM (G.-J. Roelofs, Utrecht) GOME Lauer et al., 2001; Matthes, 2003

16. Application of CCMs for sensitivity studies • E.g., assessments of future • chemical composition, • climate change, • feedback processes • in the lower stratosphere, in particular with respect to ozone.

17. E39/C - predictions Southern / Northern Hemisphere spring time 1990 2015 adapted from Schnadt et al., 2002

18. TOMS E39/C E39/C and others - predictions SH: ozone recovery expected to begin within the range 2001 to 2008 NH: ozone recovery expected to begin within the range 2004 to 2019 Austin, Schnadt, Dameris, et al., 2003

19. Evaluation of CCMs - user requirements • Satellite data products are required for validation of CCMs! • Global coverage (hor. resolution: 50*50 km2). • Long-term observation of spatial-temporal variability (inter-annual, seasonal, diurnal) of dynamical, physical and chemical parameters, in particular temperature, wind, cloud cover, H2O, CH4, O3, CO, OH, NOx, HNO3,N2O, aerosol microphysics. • Profiles (vert. resolution: 1 km; troposphere: at least 2-3 independent pieces of height resolved information, with one point in the boundary layer). • Temporally high-resolution sampling (troposphere: 60 min.; stratosphere: 3 hours).

20. Evaluation of CCMs - user requirements Geostationary platforms are required! (3-5 missions necessary to get global coverage)

21. The End. • Thank you!