Telescopic High Speed Observations of Sprites Geoff Mc. Harg 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 14 -15 July 2010 500 mm Phantom 7. 3 1. 26 x 0. 63 o FOV 43 mrad/pixel 16000 fps 85 mm Phantom 7. 0 7. 3 x 3. 7 o FOV 249 mrad/pixel 10000 fps 25 mm Watec 14. 2 x 10. 4 o FOV Az-El mount Handtriggered Two remote triangulation sites— Watec only
Example 15 July 2010— 07: 06: 09 UT • C sprite—Range=311 km • Spatial mapping Watec with C 1 – C 1 (85 mm): 77 m/pix – C 2(500 mm): 13 m/pix • Halo – Evident in C 1 – Not as clear in C 2 • Splitting evident in both C 1 1 ms avg. with C 2 FO Note: Splitting of left streamer below c 2 FOV, while right streamer splits in C 2 FOV and C 2 FOV
07: 06: 09 splitting • Kammae notes similarity of large streamer with lab streamers (AGU-2010) • Mc. Harg et al. [2010] reported on splitting streamers using 300 mm lens – Wider streamers split (390 m), narrow streamers propagate (193 m) – Streamers brighten before they split • New observations reveal – Streamers splitting into multiple smaller pieces (8 in this case) – Streamers as narrow as ~40 m – Pdmin dependent on altitude but ~1 bar-mm if @ 75 km
Example 14 July 2010— 04: 58: 55 • Jellyfish—Range=421 km • Spatial mapping – C 1 106 m/pix – C 2 18 m/pix • Halo very obvious in C 1, again less so in C 2 • Very short, ~5. 5 ms C 1 1 ms avg. with C 2 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 C 1 • Make conclusions about intensity variations in C 2 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 ~40 m observed • Higher speeds and more resolution still warranted AGU Dec 2007. AE 42 A-07
Скачать презентацию Telescopic High Speed Observations of Sprites Geoff Mc
2db6a8cc46c77fa06080ab21a8823d99.ppt