1. FOUR MAJOR RESEARCH CHALLENGES FOR 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. 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
“Bottom-up” source/sink inventories
INFLOW
OUTFLOW
3-D MODELS
inversion
“Top-down”
constraints
SATELLITES
continuous
monitoring
AIRCRAFT MISSIONS
covariances,
chemistry,
model errors
Gap in draft document: recognize essential role to be played by geostationary satellites, inverse methods, chemical data assimilation

3. HEMISPHERIC/GLOBAL POLLUTION BACKGROUND
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. 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 GCMs including aerosols/chemistry/biosphere and global/regional coupling
Climatic effects on air pollution meteorology, emissions, chemistry
Radiative
forcing
Precursor
emissions
Could be large
(remember
summer of ’88!
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. Measuring, understanding, and predicting long-term trends in the oxidizing power of the atmosphere
Need better global OH proxies, better understanding of HOx/NOx/O3 chemistry (partial derivatives), better understanding of related emissions
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