A Statistical Survey of Sprite Streamer Splitting

Wednesday, 17 December 2014
Ryan K Haaland, Fort Lewis College, Durango, CO, United States, Matthew G McHarg, United States Air Force Academy, Department of Physics, Colorado Springs, CO, United States, H C Stenbaek-Nielsen, University of Alaska Fairbanks, Fairbanks, AK, United States, Ningyu Liu, Florida Institute of Technology, Melbourne, FL, United States and Takeshi Kanmae, Geophysical Institute, Juneau, AK, United States
A fundamental understanding of streamers includes the dynamics of streamer tip splitting. Previous work has shown that sprite streamers become wider and brighter immediately before splitting (McHarg et. al [2010].) We extend this work and present a statistical survey of sprite streamer splitting and propagation based on observations made with two intensified, high-speed, CMOS cameras with high temporal and spatial resolution. We determine the number of streamer tips present after splitting and the number of splitting events as a function of angle from the local vertical for a variety of different sprites. We also compare the relative distances between splits, as well as the streamer widths immediately preceding splitting for different sprite events. Where feasible we triangulate the altitudes of the splitting events and categorize them based on the distance, and time, from the causative lightning strike. We relate these measurements to the physical processes that may lead to streamer tip splitting.

McHarg, M. G., H. C. Stenbaek-Nielsen, T. Kanmae, and R. K. Haaland (2010), Streamer tip splitting in sprites, J. Geophys. Res., 115, A00E53, doi:10.1029/2009JA014850.