1. ATMOSPHERIC CHEMISTRY APPLICATIONS WORKSHOP 20-21 January 2004, ESTEC Albert P H Goede Objective of the Workshop User Consultation on present and future needs for atmosphere chemistry observations Definition of Integrated Global Observation System, notably the satellite component

2. Atmospheric Chemistry Applications Climate ChangeChemistry-climate interactions, UTLS, atmospheric composition & trends, IPCC assessments Montreal and Kyoto Protocol Monitoring and Verification stratospheric ozone, surface UV, GHG emissions, Policy support Troposphere Cleansing power of atmosphere/trend Chemistry free troposphere Air Pollution CLRTAP (Convention Long-Range Transport), EC directives on air quality, Policy support Forecastsozone layer and surface UV chemical weather, improvement of NWP aviation management

3. User input required on all 5 issues listed User Needs and requirements (example, long term record total ozone, regional forecast air pollution etc, specify region/spatial resolution/temporal resolution/ averages, list of data products.) User Segment (example, regional environmental agency, weather service, climate change agency etc) Policy foundation (example, Kyoto, CLRTAP etc) Science review (what are the underlying science issues, what do we know, what is still uncertain, ) Strategy for Integrated Observation System (What infra structure is there on ground, in space and how to improve or fill gaps. What can be achieved in 2, 5, 10 years time and how to go about.)

4. Working Group Composition WG 1Air Quality Monitoring (chair Boucher/rapporteur Monks) ETCACC RIVM+NILU, ADEME, ITC, EMPA, EPA, GMES-Daedalus, CERMES WG 2 Montreal, Kyoto Protocol Monitoring (ch Barrie, rap Raes) WMO, NILU, GMES-GATO, JRC-IES, RIVM-UV WG 3 Climate Chemistry (chair van Weele, rapporteur Kerridge) DLR-IAP, KNMI, JRC, KfA Julich, SPARC, research groups WG 4 Tropospheric Chemistry (chair Bovensmann, rap Krol) MPI-Hamburg, U Heidelberg, IGBP-IGAC, ACCENT, LISA, other research groups WG 5 Forecasting (chair Peuch, rapporteur Fishman) Meteo-France, DWD, DMI, KNMI, INERIS, LISA, VITO

5. User Segment Scientific users in research institutes inc. met centres Expert groups (eg IPCC, WNO-UNEP)who advise policy makers

6. User Need Radiatively active constituents (mediate climate-composition interaction) nb H2O,O3,aerosol, cirrus (CH4) Spatially-variable ones from space Those which interact through chemistry (eg CO, HNO3, NOx) T + other associated dynamical (incl tracers) and physical variables (met) Geographical domain: global Height domain: troposphere +(part of) stratosphere Time domain: decadal Sampling/resolution Vertical: generally 2km or better (especially in trop) Horizontal: ~10(’s) km2 (controlled by cloud in lower trop) Sampling/res requirements lower in stratosphere Daily (at least) Precision/accuracy: typically ~10%

7. Policy foundation IPCC,WMO,GMES Indirect: Montreal, Kyoto

8. Science review Firm scientific foundation from a number of earlier international studies(eg Explorer)and parallel (eg IGACO)reports, and as outlined in Workshop presentations. ->Interactions between atmospheric composition and climate are not well understood -> Strong rationale to make global observations of key constituents and physical (met)variables on a long-term basis

9. Strategy Exploit available observations and associated infrastructure (eg for assimilation in climate centres) Ground-based networks Current space (eg ERS-2, Envisat, Odin, Aura) Planned operational space (MetOp, NPOESS) Models Complement (perspective, wavelength?) and extend (for continuity) eg through: New research missions (eg STEAM, GLORIA, Explorer?) New operational missions(parallel or beyond MetOp/NPOESS) Model development International co-operation