Tuija I Pulkkinen, University of Michigan, Department of Climate and Space Sciences and Engineering, Ann Arbor, United States, Qusai Abdulla Al Shidi, University of Massachusetts Lowell, Lowell, MA, United States, Shannon C Hill, Emory University, Physics, Atlanta, GA, United States, K Emilia J Kilpua, University of Helsinki, Helsinki, Finland and Daniel N Baker, University of Colorado, Laboratory for Atmospheric and Space Physics, Boulder, CO, United States