A new study by an international team of researchers, led by Forschungszentrum Jülich in Germany and co-authored by scientists at the National Center for Atmospheric Research (NCAR), has deciphered the dominant mechanism in the formation of formic acid in the atmosphere. The finding will help scientists to further refine atmospheric models and improve our understanding of weather and climate.

The acidity of the atmosphere is increasingly determined by carbon dioxide and organic acids such as formic acid. This acid contributes to the formation of airborne particles that lead to raindrops, and it influences the acidity of precipitation. The chemical processes behind the formation of formic acid, however, have not previously been well understood, and it tended to play a small role in previous atmospheric chemistry models. 

In the new study, the researchers determined the chemical processes that lead to most atmospheric formic acid, and they confirmed their finding through computer models and observations. NCAR contributed measurements of atmospheric chemistry.

"Data from our instruments and  network observations have shown for some time the underestimation of formic acid by chemistry climate models,” said NCAR scientist James Hannigan, a co-author of the study. “This work has revealed a new pathway and an increase in production of formic acid by a factor of two to four. It will likely have implications for other organic acids.”

The study was published this week in Nature. 

Read the Forschungszentrum Jülich news release here.

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