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Understanding Climate-Chemistry Interactions: Modeling and Implications

This document discusses the interactions between climate and atmospheric chemistry, emphasizing the role of Climate-Chemistry Models (CCMs). It highlights the necessity of these models in analyzing long-term observations of trace gases, evaluating emission control measures, and understanding chemical processes and their feedback mechanisms in climate systems. The report covers advancements in modeling techniques, applications regarding air quality and pollution effects, and anticipates future trends in atmospheric composition, with a focus on ozone recovery and climate change responses.

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Understanding Climate-Chemistry Interactions: Modeling and Implications

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  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!

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