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Telescopic High Speed Observations of Sprites

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. Langmuir Lab—Socorro New Mexico 14-15 July 2010

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Telescopic High Speed Observations of Sprites

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  1. Telescopic High Speed Observations of Sprites Geoff McHarg1, Ryan Haaland2 Takeshi Kanmae3, and Hans Stenbaek-Nielsen3 1 United States Air Force Academy 2 Fort Lewis College 3 University of Alaska, Fairbanks

  2. Langmuir Lab—Socorro New Mexico 14-15 July 2010 500 mm Phantom 7.3 1.26x0.63o FOV 43mrad/pixel 16000fps 85mm Phantom 7.0 7.3x3.7o FOV 249mrad/pixel 10000fps 25 mm Watec 14.2x10.4o FOV Az-El mount Handtriggered Two remote triangulation sites—Watec only Observational setup

  3. 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 Watec with C1 and C2 FOV C1 1ms avg. with C2 FO Note: Splitting of left streamer below c2 FOV, while right streamer splits in C2 FOV

  4. 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 • Pdmin dependent on altitude but ~1 bar-mm if @ 75 km

  5. 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

  6. 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?

  7. 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

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