Joost de Gouw
Ph.D. in Physics, Utrecht University, the Netherlands, 1994
Senior Research Scientist
Emissions, chemistry and loss processes of organic carbon in both the gas and particle phases in the Earth's atmosphere. The atmospheric formation of secondary pollutants such as ozone and aerosol and their influence on air quality and climate. Development and use of mass spectrometric and other methods for measurements of volatile organic compounds.
Current Research: Composition and Transport of Biomass Burning Emissions
Biomass burning is a large but poorly described source of tracegas and aerosol emissions to the atmosphere. Biomass burning occurs both naturally in forest fires, but a significant fraction is human induced—for example, the burning of bio-fuels for heating and cooking, agricultural residue, and trash. In addition, the frequency and intensity of forest fires may be increasing due to higher temperatures, droughts, and earlier snowmelts in boreal regions as a result of climate change.
The impact of biomass-burning emissions on the atmosphere is poorly described for a variety of reasons. The fuels are only partially combusted, and the highly oxidized nature of the emissions poses a challenge for current analytical instruments. The variability in fuels and burning conditions gives rise to a very large variability in the chemical composition of emissions. The episodic nature of biomass burning makes it difficult to study these sources systematically during field missions.
In our work, we have studied the chemical composition of biomass burning emissions in the laboratory, as well as the long-range transport and transformation of forest-fire emissions in the atmosphere.
To characterize the emissions of trace gases, we conducted detailed measurements of biomass-burning emissions at the Fire Sciences Laboratory of the U.S. Forest Service in Missoula, MT. Using a newly developed negative-ion proton-transfer chemical ionization mass spectrometer, we identified large emissions of nitrous acid (HONO), isocyanic acid (HNCO) and several carboxylic acids. These observations are of interest for various reasons. HONO molecules readily produce free radicals in the atmosphere upon photolysis, which affects the chemical transformation of biomass-burning emissions. HNCO has not been observed previously in the atmosphere, and work is in progress to evaluate the atmospheric chemistry of this trace gas. Finally, several of the measured carboxylic acids are efficient precursors of aerosol formation in biomassburning plumes.
Forest-fire emissions have been observed during several airborne field missions conducted with the NOAA WP-3D research aircraft. For example, forest-fire plumes from Siberia were observed in the Alaskan Arctic in April 2008. This year, we studied how commonly Siberian fires contribute to the aerosol loadings in the Arctic. We found that for organic and black carbon aerosol in particular, the contribution from forest-fire emissions is very large, even in an average year. These observations are significant, as aerosol in the Arctic has been speculated to play an important role in the radiative forcing of Arctic climate as well as in the melting of sea ice and the ice sheet after deposition.
Honors and Awards
- Editor of JGR Atmospheres