Xin Chen, University of Minnesota Twin Cities, Minneapolis, MN, United States, Dylan B Millet, University of Minnesota Twin Cities, Department of Soil, Water, and Climate, St Paul, MN, United States, J A Neuman, Cooperative Institute for Research in Environmental Sciences, Boulder, CO, United States, Patrick R Veres, Earth System Research Laboratory, Chemical Sciences Division, Boulder, CO, United States, Thomas B Ryerson, NOAA ESRL Chemical Sciences Division, Boulder, CO, United States and ATom Science Team