John Lyon, Dartmouth College, Hanover, NH, United States, Kareem Sorathia, Johns Hopkins University Applied Physics Laboratory, Laurel, MD, United States, Viacheslav G Merkin, The Johns Hopkins University, Laurel, MD, United States and Binzheng Zhang, National Center for Atmospheric Research, Boulder, CO, United States; University of Hong Kong, Department of Earth Sciences, Hong Kong, Hong Kong