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2013 Southern Oxidant and Aerosol Study (SOAS)

Measuring and modeling at the interface of air quality and climate change to
understand biosphere‐atmosphere interactions

North view

The Southeastern U.S. has been a focus area in classic and historic atmospheric field studies. Natural emissions of organic compounds (e.g., isoprene and monoterpenes) in the Southeast are high, rivaling rates in tropical areas. The location is ideal to study biogenic‐anthropogenic interactions (Figure 1), due to the proximity of natural emissions with a variety of anthropogenic pollution sources. In the past decade, there has been a remarkable decrease in combustion related NOx emissions, resulting in significant changes in the chemistry of organic oxidation. The Southern Oxidant Study (SOS) spanned nearly a decade (the 1990s), involving several sites around Nashville, TN, Atlanta, GA and other locations. The Southeastern Aerosol and Visibility Study (SEAVS) took place in 1995 in the Great Smoky Mountains National Park. During the 20+ years since these intensive field studies, our understanding of biosphere‐atmosphere interactions and the subsequent influences on atmospheric oxidant chemistry and aerosol formation has dramatically improved. We now have specific knowledge of first and second generation products of isoprene photooxidation and have the beginnings of a mechanistic understanding of isoprene oxidation and secondary organic aerosol formation from isoprene, monoterpenes and sesquiterpenes. Analytical instrumentation for laboratory and in situ measurements are vastly improved, not only in temporal resolution, but in the spectrum of measurable compounds. It is now possible to explicitly quantify a variety of gas and aerosol phase species in near real time, such as: glyoxal, alkyl nitrates, epoxides, •RO2 radicals and compounds, and secondary organic aerosol tracers specific to VOC precursor. Satellite based sensors are recording changes in NOx associated with reduced emissions from electric generating units with remarkable fidelity. The experimental advances make this an opportune moment to build on the history of experiments in the Southeast to address pressing scientific questions in our field, hence the Southern Oxidant and Aerosol Study (SOAS). Further information about SOAS is provided in the white paper.

SOAS is part of a bigger campaign, Southeast Atmosphere Study (SAS), a joint project among the National Science Foundation, the Environmental Protection Agency, and 30 US and International Research Institutions, is the largest U.S. air quality study in decades.

SOAS – Look Rock Ground Site

Look Rock Site is one of SOAS ground sites where various gaseous, particle, and meteorological measurements are conducted, starting from June 1 – July 15, 2013. Principal investigators participated at this site are Dr. Jason Surratt (UNC), Dr. Lynn Russell (UC San Diego), Dr. Tim Bertram (UC San Diego), Dr. Chris Cappa (UC Davis),  and Dr. Karena McKinney (Amherst College). Measurements conducted at this site include

Surrat Group, UNC

  • NR-PM1 chemical characteristic by ACSM
  • Biogenic VOC oxidation products by Aerodyne ToF-CIMS
  • PM1 mass and size distribution by BMI SEMS/DMA

Russell Group, UC San Diego

Bertram Group, UC San Diego

Cappa Group, UC Davis

McKinney Group, Amherst College