Telescopic High Speed Observations of Sprites Geoff McHarg 1, Ryan Haaland 2 Takeshi Kanmae 3, and Hans Stenbaek-Nielsen 3 1 United States Air Force Academy 2 Fort Lewis College 3 University of Alaska, Fairbanks

Observational setup Langmuir Lab—Socorro New Mexico July mm Phantom x0.63 o FOV 43  rad/pixel 16000fps 85mm Phantom x3.7 o FOV 249  rad/pixel 10000fps 25 mm Watec 14.2x10.4 o FOV Az-El mount Handtriggered Two remote triangulation sites— Watec only

Example 15 July 2010— 07:06:09 UT C sprite—Range=311km Spatial mapping –C1 (85mm): 77 m/pix –C2(500mm): 13 m/pix Halo –Evident in C1 –Not as clear in C2 Splitting evident in both C1 1ms avg. with C2 FO Note: Splitting of left streamer below c2 FOV, while right streamer splits in C2 FOV Watec with C1 and C2 FOV

07:06:09 splitting Kammae notes similarity of large streamer with lab streamers (AGU-2010) McHarg et al. [2010] reported on splitting streamers using 300 mm lens –Wider streamers split (390m), narrow streamers propagate (193m) –Streamers brighten before they split New observations reveal –Streamers splitting into multiple smaller pieces (8 in this case) –Streamers as narrow as ~40m –Pd min dependent on altitude but ~1 bar-mm 75 km

Example 14 July 2010— 04:58:55 Jellyfish—Range=421 km Spatial mapping –C1 106 m/pix –C2 18 m/pix Halo very obvious in C1, again less so in C2 Very short, ~5.5ms C1 1ms avg. with C2 FOV Note: Telescope looking in central region of jellyfish

04:58:55 splitting Splitting at same time as development of afterglow Very fine afterglow structures form Clouds in FOV very evident in C1 Make conclusions about intensity variations in C2 suspect Could the rapid decay visible across the FOV be due to increased conductivity from streamers?

Conclusions High speed telescopic imaging yields new views of streamer dynamics –Streamer splitting shows different numbers of daughter streamers—Why? –Are streamers self-similar—or is this due to the amorphous nature of streamers and simply due to smearing? –Streamer width of ~40m observed Higher speeds and more resolution still warranted AGU Dec AE42A-07