title: Sprite streamer initiation from natural mesospheric structures.
abstract: Sprites are large, luminous electrical discharges in the upper atmosphere caused by intense cloud-to-ground lightning flashes, manifesting an impulsive coupling mechanism between lower and upper atmospheric regions. Their dynamics are governed by filamentary streamer discharges whose propagation properties have been well studied by past work. However, how they are initiated is still under active debate. It has recently been concluded that ionospheric/mesospheric inhomogeneities are required for their initiation, but it is an open question as to what the sources of those inhomogeneities are. Here we present numerical simulation results to demonstrate that naturally-existing, small-scale mesospheric structures such as those created by gravity waves via instability and breaking are viable sources. The proposed theory is supported by a recent, unique high-speed observation from aircraft flying at 14-km altitude. The theory naturally explains many aspects of observed sprite streamer initiation and has important implications for future observational work.
authors.affiliation: Department of Physics and Space Sciences, Florida Institute of Technology, Melbourne, Florida 32901, USA.
authors.forename: Ningyu
authors.initials: N
authors.lastname: Liu
authors.affiliation: Department of Physics and Space Sciences, Florida Institute of Technology, Melbourne, Florida 32901, USA.
authors.forename: Joseph R
authors.initials: JR
authors.lastname: Dwyer
authors.affiliation: Geophysical Institute, University of Alaska, Fairbanks, Alaska 99775, USA.
authors.forename: Hans C
authors.initials: HC
authors.lastname: Stenbaek-Nielsen
authors.affiliation: Department of Physics, United States Air Force Academy, Colorado Springs, Colorado 80840, USA.
authors.forename: Matthew G
authors.initials: MG
authors.lastname: McHarg