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Updated 16 September 2008

Atmospheric Composition
A USGCRP Program Element



Atmospheric Composition


Recent Accomplishments

Near-Term Plans

Archived News Postings [June 2000 - July 2005]

Related Sites

Calls for Proposals

CCSP / USGCRP Atmospheric Composition Working Group Members


For long term plans, see Atmospheric Composition chapter of the Strategic Plan for the Climate Change Science Program (2003) posted on CCSP web site.

CloudsThe composition of the atmosphere at global and regional scales influences climate, air quality, stratospheric ozone, and precipitation, which in turn affect human health and the vitality of ecosystems. Research and observational activities coordinated and supported by CCSP are being used to assess how human activities and natural processes affect atmospheric composition, and how that understanding may be used to inform decisionmaking in the United States and abroad. In FY 2009, emphasis will be placed on studies of interactions between aerosols and non-CO2 gases, enhanced measurements of atmospheric water vapor, and interactions of pollutants with climate change. Special emphasis will be placed on the climate impacts of pollutants associated with aviation.


Strategic Research Questions

3.1.  What are the climate-relevant chemical, microphysical, and optical properties, and spatial and temporal distributions, of human-caused and naturally occurring aerosols?

3.2.  What are the atmospheric sources and sinks of the greenhouse gases other than CO2 and the implications for the Earth’s energy balance?

3.3.  What are the effects of regional pollution on the global atmosphere and the effects of global climate and chemical change on regional air quality and atmospheric chemical inputs to ecosystems?

3.4.  What are the characteristics of the recovery of the stratospheric ozone layer in response to declining abundances of ozone-depleting gases and increasing abundances of greenhouse gases?

3.5.  What are the couplings and feedback mechanisms among climate change, air pollution, and ozone layer depletion, and their relationship to the health of humans and ecosystems?

See Strategic Plan for the U.S. Climate Change Science Program, Chapter 3, for detailed discussion of these research questions.

The Earth's atmosphere is composed of gases and particles that vary with spatial scale and with time, influencing climate, air quality, the stratospheric ozone layer, and weather. Interactions between these components have impacts on human health and the vitality of ecosystems and hence have high relevance to society. CCSP research on atmospheric composition focuses primarily on how human activities and natural processes affect atmospheric composition, and how these changes in turn relate to societal issues. The issues embrace multiple disciplines, cross many spatial scales, and are highly interrelated. Consequently, CCSP research is a highly coordinated endeavor that involves observational studies, laboratory investigations, and modeling analyses to provide the timely, accurate, and useful scientific information needed by decisionmakers nationally and internationally.

Progress has been made to date in understanding the role of atmospheric composition in Earth's climate. Efforts have been dedicated to the areas of largest uncertainty in understanding how atmospheric constituents other than carbon dioxide (CO2) affect the forcing of climate. Atmospheric fine particles ("aerosols") can have either warming or cooling effects, depending on many factors. CCSP research has made progress in defining those factors, and has recently taken steps to address the next levels of complexity in the issue by looking at the interactions of aerosols with clouds. For FY 2009, CCSP's atmospheric composition research will focus on aerosols and aerosol/cloud interactions in the polar environment through analyses of measurements from satellites, aircraft, and the surface made during the International Polar Year (spring 2007 to summer 2008). Additional FY 2009 work focuses on linked air qualityclimate modeling systems, future emission projections, and communicating research results to air quality decisionmakers.


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