Issue

Air pollutants near the Earth’s surface can be lofted to higher altitudes in the atmosphere, where strong winds can efficiently transport them from one continent to another. This means that pollution in one area can affect air quality on intercontinental and global scales. When emission levels are changed in one area—by new policies, or by increased industrialization, for example—the impacts of long-range pollutant transport on background pollutant levels can drastically change.

This makes it difficult to determine the best ways to reduce surface air pollution levels for many regions. Not only do policymakers have to account for local emissions sources; they must also be able to predict the complex atmospheric processes that happen from the local-to-global scales, over timeframes that range from seconds to years.

Action

As allowable levels of air pollutants become lower, it is increasingly important for scientists to be able to understand exactly where pollution comes from – whether the sources are local emissions, or whether pollutants have been transported from other parts of the world. We also need reliable information on the composition, size, and distribution of particulate matter in order to understand how it can alter the way the sun’s rays reach the earth and affect the “radiation budget” of the atmosphere. To address these needs, comprehensive modeling frameworks representing complex interactions between physical, chemical and dynamical processes are being developed at local-to-global scales.

Results and Impacts

The development of these “local-to-global” tools will provide a consistent and robust framework to examine the role of intercontinental transport on U.S. air pollution, and help understand not only the impacts of global climate change on air quality, but also how domestic sources contribute to the changing global climate.

Some illustrations:
Examining U.S. Air Quality in context of Global Air Quality
 

Next-generation local-to-global modeling system