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April 10th, 2010

Volatile organic compounds in the global atmosphere

Detlev Helmig led a team from six countries to summarize initial results of a global monitoring network for volatile organic compounds (VOCs). Although still being built, the global VOC network is already yielding insights into how the complex interactions associated with these organic chemicals influence climate and air quality. Among other roles, VOCs interact with nitrogen oxides in the lower atmosphere and sunlight to produce ozone and other chemicals. Such ozone is now the third most important anthropogenic greenhouse gas after carbon dioxide and methane. Ozone and other chemicals associated with VOCs have led to poor air quality and damaged vegetation in many industrialized nations.

Jacques Hueber perches on a meteorological tower near the Mountain Research Station.

The new global dataset shows strong seasonal cycles for all individual VOCs and large differences in the concentration and timing of some VOCs between the Northern and Southern Hemisphere. The details of such differences provide a better understanding of the production and depletion of VOC's as well as the overall reactivity of the atmosphere. The data are helping improve coupled chemistry and climate models, including those used to further decipher sources and sinks of greenhouse gases. Moreover, some VOC records are now sufficiently long and precise to detect regional patterns such as the decline in short-lived VOCs in Europe associated with gasoline reformulation and stricter VOC emission limits. Because of the clear importance of VOCs to both global and regional issues, the World Meteorological Organization (WMO) Global Atmosphere Watch (GAW) has been guiding the implementation of the global VOC monitoring program.

The team's summary was the cover story of the 29 December 2009 issue of Eos, the weekly refereed "newspaper" of the American Geophysical Union. Additional materials about the team's work are available as an online supplement to their Eos article.