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Yusuf Hamied Department of Chemistry

 

Image courtesy of Loretta Kuo/Shawn Honomichi

A US/UK campaign looking at the remote tropical atmosphere over the West Pacific has produced exciting insights into the effects of biomass burning on its composition, and the role of the burning of forests and vegetation in climate change.

Neil Harris, the principal investigator on the Natural Environmental Research Council’s Coordinated Airborne Studies in the Tropics (CAST) mission, collaborated with several US and UK research teams, in a campaign which measured the levels of dozens of chemicals in the atmosphere over the tropics during January and February 2014.

For the study, the CAST research plane flew up to 24,000 feet over Guam, a remote island in the Pacific Ocean, to measure atmospheric composition.  Another research craft flew up to 48,000 feet as part of the CONvective Transport of Active Species in the Tropics (CONTRAST) mission.

A study analysing the collected measurements, satellite data and a variety of models has been published online today in the journal Nature Communications.  Researchers conclude that fires burning in tropical Africa and Southeast Asia caused pockets of high ozone and low water in the lower atmosphere above Guam—even though it is more than 1,700 miles east of Taiwan.

“International collaboration is essential for studying global environmental issues these days,” says Neil, a senior researcher in the department’s atmospheric science group.  “This US/UK campaign over the western Pacific was the first of its kind in this region and collected a unique data set.  The measurements are now starting to produce insight into how the composition of the remote tropical atmosphere is affected by human activities occurring nearly halfway around the world.”

Researchers examined 17 CAST and 11 CONTRAST flights and compiled over 3,000 samples from high-ozone, low-water air parcels for the study. In the samples, the team detected high concentrations of chemicals associated with biomass burning—hydrogen cyanide, acetonitrile, benzene and ethyne.

“We were very surprised to find in the air around Guam, high concentrations of ozone and chemicals that we know are only emitted by fires,” said the study’s lead author Daniel Anderson, a graduate student in the University of Maryland Department of Atmospheric and Oceanic Science. “We didn’t make specific flights to target high-ozone areas—they were so omnipresent that no matter where we flew, we found them.”

Based on the results of this study, global climate models may need to be reassessed to include and correctly represent the impacts of biomass burning, deforestation and reforestation, which may play a larger role in climate change than previously realised.

Image shows the British Facility for Airborne Atmospheric Measurements (FAAM) BAe-146 research aircraft in the NERC CAST mission, and the US-based High-performance Instrumented Airborne Platform for Environmental Research, a Gulfstream V jet sponsored by the National Science Foundation and the National Center for Atmospheric Research.