Margot Clyne, University of Colorado at Boulder, Department of Atmospheric and Oceanic Sciences, Boulder, CO, United States, Owen B Toon, Univ Colorado Boulder, Boulder, CO, United States, Michael J Mills, National Center for Atmospheric Research, Atmospheric Chemistry, Observations, and Modeling Laboratory, Boulder, CO, United States and Yunqian Zhu, University of Colorado at Boulder, Boulder, CO, United States