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THEMIS

First light: Nature’s welcome. Two substorms seen on March 23. http://sscweb.gsfc.nasa.gov/tipsod. DETAILED VIEW. THEMIS. TH-E. THE. Y. Y. TH-A. Z. TH-B. TH-D. X. TH-C. SUN. THA. THB. X. THC. THD. Z. SUN. POLAR. From UVI. At 11:18:26UT. First brightening @ 23MLT

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THEMIS

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  1. First light: Nature’s welcome. Two substorms seen on March 23 http://sscweb.gsfc.nasa.gov/tipsod DETAILED VIEW THEMIS TH-E THE Y Y TH-A Z TH-B TH-D X TH-C SUN THA THB X THC THD Z SUN POLAR

  2. From UVI At 11:18:26UT. First brightening @ 23MLT By 11:19:40UT. Auroras expand to 21.5MLT By 11:23:21UT No further expansion observed Consistent with VIS due to 0.5MLTUVI uncertainty from POLAR wobble

  3. From VIS: 2007_082_1008-1309_all.mov At 11:18:03-45UT. Auroras brighten @ 23MLT By 11:19:57UT. Auroras expand to 22MLT By 11:23:21UT No further expansion observed

  4. Keograms from UVI

  5. At 11:18:42UT. From: 3_23_07_mosaic.mov Auroras match across FOVs Onset at 18:42UT@ 23MLT At 11:19:00UT. From: 3_23_07_mosaic_Alaska_2.mov Auroras do not match at FOVs Not much westward expansion Still @ 23MLT 22 23 00MLT

  6. Apatenkov/Sergeev model:SCW Upward FACjumps to 21.5MLT andstays there for >20 minutes

  7. Apatenkov/Sergeev model:SCW Upward FAC

  8. Classical mapping Tsyganenko 2001mapping: THEMIS maps to21.5 MLT (other models, orhigher activity place thm tothe West). 21.5MLT

  9. Simulation mapping OpenGGCM mapping:THEMIS just before simulation onset maps to ~22.5 MLT, i.e.,right in the middle of expandingactivation. Note: mapping evolves

  10. ____ ____ ____ X: Y: Z: TH-FGL Overview THA-FGM FIT Data (3s) Available Substorm Onset POLAR UVI/VIS Onset 10:58UT Intensifications

  11. Z=SMZ Rxy rotated X= - Ewd

  12. THEMIS Energetic Particles, Overview 11:18 11:19 046, e 97A, p 11:19 1989-046 LANL-97A THEMIS-C THEMIS-D A B [Wenlong Liu and Xinlin Li]

  13. C (fgm) C (sst) Clear dipolarization with a propagation or expanding speed of 200~300 km/s along GSM y direction. Injection occurs ~10-30s earlier than dipolarization D (fgm) D (sst) B (fgm) B (sst) A (fgm) A (sst) E (fgm) E (sst)

  14. Expansion speed on the ground ~ 1 MLT hrs/min • Observed speed in space (from time delays) is ~250km/sFrom 10RE it maps on the ground to ~1 MLT hrs/min • Therefore: • Observed speed in space matches speed on the ground • Expansion speed is the maximum expected from statistics(Nagai ’91: ~ 1MLT/min, 0.5MLT from central meridian) • There is no continuous expansion of the WTS in this case.This was a new activation appearing Westward of old one.Likely the norm?

  15. Another example Mende et al, GRL 2007

  16. Moments Overview TH-D

  17. Summary, March 23 11:18 onset • First direct detection of Westward Traveling Surge motion in the magnetosphere • 200km/s westward motion consistent with expectation from ground data • Expansion is motion of activity westward, flows are Earthward and duskward • Simultaneous inward and outward expansion of the injection • Azimuthal effects are dominant in this case THEMIS tail alignments in 2008 will be able to resolve temporal relationship and relative motion of current disruption, dipolarization and particle injections, one of the primary THEMIS objectives

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