Emmanuel Assaf, Cooperative Institute for Research in Environmental Sciences (CIRES), NOAA Boulder, ESRL/CSD, Boulder, CO, United States, Paul Marshall, University of North Texas, Chemistry, Denton, TX, United States, Patrick R Veres, Earth System Research Laboratory, Chemical Sciences Division, Boulder, CO, United States, James M Roberts, NOAA/ESRL, Boulder, CO, United States, J A Neuman, Cooperative Institute for Research in Environmental Sciences, Boulder, CO, United States and James B Burkholder, NOAA Boulder, ESRL/CSD, Boulder, CO, United States