FOUR MAJOR RESEARCH CHALLENGES FOR THE SECOND DECADE OF THE USGCRP

1. FOUR MAJOR RESEARCH CHALLENGESFOR THE SECOND DECADE OF THE USGCRP • Quantify the contributions from major geopolitical source regions to the global budgets of environmentally important gases and aerosols (cross-cuts atmospheric composition questions 1, 2, 3, 5) 2. Quantify the role of intercontinental transport of pollution on regional environmental degradation (question 3) 3. Understand the effects of air pollutants (ozone, aerosols) on climate, the related feedbacks, and the effects of climate change on air quality (cross-cuts questions 1, 2, 3, 5) 4. Measure, understand, and predict long-term trends in the oxidizing power of the atmosphere (cross-cuts all questions) • Two general points: • Satellite observations to revolutionize research over next decade • Climate sensitivity issues critical but don’t neglect broader environmental issues (overlaps, feedbacks e co-benefits, community inclusion)

2. SATELLITES continuous monitoring “Top-down” constraints 3-D MODELS inversion AIRCRAFT MISSIONS covariances, chemistry, model errors OUTFLOW INFLOW “Bottom-up” source/sink inventories Quantifying the contributions from major geopolitical source regions to the global budgets of environmentally important gases and aerosols Need inverse models constrained by satellite and aircraft observations, and by bottom-up understanding of processes Gap in draft document:recognize essential role to be played by geostationary satellites, inverse methods, chemical data assimilation

3. Quantifying the role of intercontinental transport of pollution in regional environmental degradation Need global mapping (satellites), 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 (metals, POPs) Gap in draft document: broaden to metals and POPs (multimedia models)

4. Could be large (remember summer of ’88! Understanding 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 Radiative forcing Precursor emissions Aerosols Tropospheric ozone, Gap in draft document: need observational diagnostics of radiaitive and climatic response to aerosols and ozone, climate forecasts relevant to air pollution meteorology

5. Need better global OH proxies, better understanding of HOx/NOx/O3 chemistry (partial derivatives), better understanding of related emissions Measuring, understanding, and predicting 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 Gap in draft document: oxidizing power of atmosphere is nowhere specifically addressed