Interpreting Satellite and In Situ Observations of Atmospheric Composition to Improve Understanding of Air Quality and Climate Processes

Pressing scientific questions in air quality and climate will be addressed using a combination of satellite observations, ground-based measurements, and a global three-dimensional model of atmospheric composition. Emphasis will be placed on quantitative interpretation of satellite observations of atmospheric particles, of their precursors, and of ozone precursors in the troposphere (lowest 12-17 km of the atmosphere). Atmospheric particles degrade health and visibility, and have highly uncertain effects on climate. Tropospheric ozone is a greenhouse gas, a pollutant, and largely controls the breakdown of other pollutants. Both atmospheric particles and tropospheric ozone can be produced locally and can be transported from afar. Precursors for atmospheric particles and tropospheric ozone include ammonia, sulfur dioxide, nitrogen oxides, and organics. Specific objectives of the research program include 1) evaluate and improve simulations of precursors of atmospheric particles and ozone through comparison with satellite and ground-based measurements, 2) enhance the representation of atmospheric particle processes in global models, and 3) develop improved satellite-based estimates of global ground-level fine particulate matter (PM2.5) for air quality and health applications. Achieving these objectives would reduce uncertainty in critical atmospheric processes that impair current efforts to improve air quality and respond to climate change.