Oxidation of biogenic volatile organic compounds (BVOCs) leads to the formation of secondary organic aerosols (SOA). The production of SOA from BVOCs is greatly modulated by anthropogenic NOx emissions, but the role of SOA in climate system and how anthropogenic activity plays a role is largely unknown. Southeast US is heavily influenced by both anthropogenic and biogenic emissions. In particular, anthropogenic NOx emissions have been substantially reduced in the past decade, providing an unprecedented opportunity to evaluate the anthropogenic influence on the formation of secondary organic aerosol on a decadal scale. We aim to advance the science in this area by addressing the following questions:
How do SOA and its precursors (isoprene epoxydiol (IEPOX), organic nitrates and glyoxal) respond to NOx emission changes in Southeast US?
What are the possible drivers for this declining trend of organic aerosol over Southeast US? Can we use the trend of organic aerosol in Southeast US to quantify the anthropogenic influence on biogenic SOA?
Can we extend estimates of this anthropogenic influence from decadal scale to the century scale, to better quantify the radiative forcing from biogenic SOA from the preindustrial period to the present day? What are the uncertainties associated with this estimate?