FIVE CHALLENGES IN ATMOSPHERIC COMPOSITION RESEARCH

1. FIVE CHALLENGESIN ATMOSPHERIC COMPOSITION RESEARCH • Exploit satellite and other “top-down” atmospheric composition data to quantify emissions and export of environmentally important gases and aerosols 2. Quantify the role of intercontinental transport of pollution on regional environmental degradation 3. Understand the effects of air pollutants (ozone, aerosols) on climate, the related feedbacks, and the effects of climate change on air quality 4. Measure, understand, and predict long-term trends in the oxidizing power of the atmosphere 5. Use atmospheric composition data to improve numerical weather prediction

2. Exploit satellite and other “top-down” atmospheric composition data to quantify emissions and export of environmentally important gases and aerosols Need inverse models constrained by satellite and aircraft observations, and by bottom-up understanding of processes; geostationary satellites would increase capability tremendously “Top-down” constraints on emissions and export SATELLITES continuous monitoring 3-D MODELS Hindcasts/forecasts (experimental design) Inversions AIRCRAFT MISSIONS covariances chemistry model errors satellite validation SURFACE SITES long-term trends surface fluxes INFLOW OUTFLOW “Bottom-up” source/sink inventories

3. Quantify the role of intercontinental transport of pollution in regional environmental degradation Need global mapping (satellites), aircraft campaigns, long-term observations, integrated approach (ozone, aerosols, Hg, POPs…), new generation of models to resolve regional-global and ocean-atmosphere coupling HEMISPHERIC/GLOBAL POLLUTION BACKGROUND (Ozone, metals, POPs) Free troposphere PBL “Direct” intercontinental transport (aerosols) Continent 1 Continent 2 Oceanic transport (Hg, POPs)

4. Could be large (remember summer of ’88! Understand the effects of air pollutants (ozone, aerosols) on climate, the related feedbacks, and the effects of climate change on air quality Need better characterization of aerosol forcing, new generation of GCMsincluding aerosols/chemistry/biosphere and global/regional coupling Climatic effects on air pollution meteorology, emissions, chemistry Inhomogeneous radiative forcing – is radiative forcing even an useful concept? Precursor emissions Aerosols Tropospheric ozone

5. Need better global OH proxies, better understanding of HOx/NOx/O3 chemistry (partial derivatives), better understanding of related emissions Measure, understand, and predict long-term trends in the oxidizing power of the atmosphere O2 + hn Stratospheric ozone STRATOSPHERE STE (poorly understood) ? Tropopause (8-18 km) TROPOSPHERE Complex non-linear chemistry ? Lightning ? hn hn, H2O Nitrogen oxides (NOx) CO, Hydrocarbons Ozone (O3) Hydroxyl (OH) the main atmospheric oxidant

6. Use tropospheric composition data (CO, ozone) to improve numerical weather prediction Need to develop chemical data assimilation tools, integrate correlated atmospheric composition data and surface data (e.g. fire maps) Satellite observations of CO, O3 Chemical data assimilation UT lifetime ~ months Ozone Tropospheric ozone has complicated chemistry but is a good tracer of vertical transport CO is conserved in wet processes; 2-month lifetime e tracer of long-range transport LT lifetime ~ days CO combustion source