BOX 12.
ATMOSPHERIC CHEMISTRY
The chemistry of the atmosphere, Earth's ecosystems, human health, and economic systems are inextricably
linked, often in complex ways. Research supported by NSF and other Federal agencies has created tremendous
progress in understanding stratospheric chemistry. However, many questions remain unresolved, such as the
exact nature of stratospheric aerosols and the detailed linkages between their chemistry and dynamics. Current
areas of interest also include the connection between stratospheric ozone depletion and climate changethe
stratosphere is actually cooling. The lower stratosphere/upper tropospherepreviously not easily accessible to
direct observationhas recently come into focus since much of its chemistry and dynamics, including
stratosphere/troposphere exchange, are poorly understood. Tropospheric chemistry remains full of challenges:
defining its oxidative capacity (which in turn determines the ozone depletion potentials and global warming
potentials of harmful compounds); understanding the factors affecting regional and global air quality; feedback
mechanisms between global climate change and the chemical processes; and a complete understanding of
biogeochemical cycles that link atmospheric, oceanic, and biological processes.
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