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Substorms

Substorms. GEM Student tutorial Christine Gabrielse, UCLA June 16, 2013. Storms. cgabrielse@ucla.edu. GEM Student Day, 2013 June 16. Substorms. cgabrielse@ucla.edu. GEM Student Day, 2013 June 16. Substorms. Onset: auroral brightening.

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Substorms

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  1. Substorms GEM Student tutorial Christine Gabrielse, UCLA June 16, 2013

  2. Storms cgabrielse@ucla.edu GEM Student Day, 2013 June 16

  3. Substorms cgabrielse@ucla.edu GEM Student Day, 2013 June 16

  4. Substorms Onset: auroral brightening Onset: sharp perturbation in magnetometer observations Onset: reconnection, dipolarization …in the ionosphere …on the ground …in space cgabrielse@ucla.edu GEM Student Day, 2013 June 16

  5. The “Auroral Substorm” T=0. Quiet arcs drift equatorward. T=0-5 min. Onset: Sudden brightening of equatorward arc in premidnight sector T=5-10 min. Expansion Phase: Bright, dynamic auroral bulge forms T=10-30 min. Westward-traveling surgeOmega bands form to the east T=30-60 min. Pulsating patches appear at eastern equatorward edge T= 1-2 hours. Recovery phase: Pulsating patches continue as auroral activity dims and quiet arcs return Omega bands [Akasofu, 1964] cgabrielse@ucla.edu GEM Student Day, 2013 June 16

  6. The “Auroral Substorm” • T=0. Quiet arcs drift equatorward. • T=0-5 min. Onset: Incoming streamer sudden brightening near midnight • T=5-10 min. Expansion Phase • T=10-30 min. Westward-traveling surge • T=30-60 min. Pulsating patches appear North South Credit: University of Alaska, Fairbanks South Credit: Nishimura et al., 2012 THEMIS All-sky-imagers North cgabrielse@ucla.edu GEM Student Day, 2013 June 16

  7. Substorms in Space cgabrielse@ucla.edu GEM Student Day, 2013 June 16

  8. Substorms in Space • NENL=Near-Earth • Neutral Line (X-line) • Localized phenomenon • Bursty bulk flows (BBFs) only few RE wide Plasmoid Modified from Hones [1977] cgabrielse@ucla.edu GEM Student Day, 2013 June 16

  9. Substorms in Space Fast flow from reconnection Red=strong flow AE [nT] Psuedobreakup -8RE B [nT] Vz V [km/s] Tail stretching Dipolarization Earth Y V Vy Vx Bursty Bulk Flows (BBFs) E mV/m Depleted flux tube 8RE Ni [1/cc] X -23RE -8RE From Figure 5 in Birn et al. [2011] eV eV NENL Particle InjectionsChorusPulsating aurora

  10. Ground Observations Substorm Current Wedge Modified from Reistad, UNIS AGF-345

  11. Substorm Phases cgabrielse@ucla.edu GEM Student Day, 2013 June 16

  12. Gem Focus Groups • Substorm Expansion Onset: The First 10 Minutes: • Tuesday, 10:30 - 12:15, 1:30-5:00, Salon D • Relative timing between onset signatures in space & on the ground • The role of magnetotail reconnection (distant and near-Earth) in substorms and substorm-related processes • Substorm-related processes in the tail-dipole transition region • Substorm onset mapping (joint with the Magnetic Mapping and Techniques Focus Group) • Modes of Solar Wind-Magnetosphere Energy Transfer: • Thursday, 10:30-12:15; 1:30-3:00, Cathedral Peak • Tail-Inner Magnetosphere Interactions: • Monday, all sessions, Cathedral Peak • Tuesday, 10:30 - 12:15, Cathedral Peak cgabrielse@ucla.edu GEM Student Day, 2013 June 16

  13. References • Slide 1 Aurora Image: http://thewatchers.adorraeli.com/2012/03/18/aurora-sub-storm-march-1516-2012-timelapse-and-gallery/ • Kyoto AE/AL Indices: http://wdc.kugi.kyoto-u.ac.jp/ae_provisional/200802/index.html • Acknowledgments: We thank AE stations (Abisko [SGU, Sweden], Dixon Island, Cape Chelyuskin, Tixie Bay, Pebek [AARI, Russia], Barrow, College [USGS, USA], Yellowknife, Fort Churchill, Sanikiluaq (Poste-de-la-Baleine) [GSC, Canada], Narsarsuaq [DTU Space, Denmark], and Leirvogur [U. Iceland, Iceland]) as well as the RapidMAG team (NiCT, JHU/APL, UoA, AARI, and IDG) for their cooperations and efforts to operate these stations and to supply data with us for the provisional AE index. • Slide 4 Aurora Image: http://asterisk.apod.com/viewtopic.php?f=29&t=23109 • By Kwon, O. Chul. Taken by fish-eye lens at Yellowknife, Canada. 2011-02-23. • Slide 4 Ground Magnetometer Map: http://supermag.uib.no/ • SuperMAG cgabrielse@ucla.edu GEM Student Day, 2013 June 16

  14. References • Omega Band image: http://ham.space.umn.edu/spacephys/aurora_gallery/aurora_answers.html • Ektachrome photo by John R. Winckler, 14 July 1991, from University of Minnesota O'Brien Observatory, Marine-on-the-St. Croix, Minnesota. • Slide 10 Substorm Current Wedge image from R. McPherron UCLA ESS 154 course • Slide 10 verbal reference to Liu et al., 2013 JGR (on the topic of dipolarization fronts carrying in field-aligned currents, resulting in the substorm current wedge). • Slide 11 from R. McPherron UCLA ESS 154 course and • Extra Slide Auroral Oval Image: http://www.sos.noaa.gov/Datasets/dataset.php?id=380 • NOAA cgabrielse@ucla.edu GEM Student Day, 2013 June 16

  15. Substorms Extra cgabrielse@ucla.edu GEM Student Day, 2013 June 16

  16. Auroral Oval Auroral oval “maps” to plasma sheet cgabrielse@ucla.edu GEM Student Day, 2013 June 16

  17. The “Auroral Substorm” Use a movie from the THEMIS asi of a substorm T=0. Quiet arcs drift equatorward. T=0-5 min. Onset: Sudden brightening of equatorward arc in premidnight sector, expanding westward and poleward. T=5-10 min. Expansion Phase: Bright, dynamic bulge of auroral disturbance forms near onset T=10-30 min. Westward-traveling surge: Auroral bulge develops sharp kink at westward edge which propagates westward. Omega bands form to the east. T=30-60 min. Pulsating patches of aurora appear at the equatorward edge in the east. Auroral activity dims. T= 1-2 hours. Recovery phase: Pulsating patches continue as auroral activity dims and quiet arcs return. cgabrielse@ucla.edu GEM Student Day, 2013 June 16

  18. The “Auroral Substorm” T=0. Quiet arcs drift equatorward. T=0-5 min. Onset: Incoming streamer leads to sudden brightening of equatorward arc in premidnight sector T=5-10 min. Expansion Phase: Bright, dynamic auroral bulge forms T=10-30 min. Westward-traveling surge North South Credit: Nishimura et al., 2012 THEMIS All-sky-imagers cgabrielse@ucla.edu GEM Student Day, 2013 June 16

  19. The “Auroral Substorm” T=0. Quiet arcs drift equatorward. T=0-5 min. Onset: Sudden brightening of equatorward arc in premidnight sector T=5-10 min. Expansion Phase: Bright, dynamic auroral bulge forms T=10-30 min. Westward-traveling surge: Auroral bulge develops sharp kink, propagates westward. Omega bands form to the east. T=30-60 min. Pulsating patches of aurora appear at eastern equatorward edge T= 1-2 hours. Recovery phase: Pulsating patches continue as auroral activity dims and quiet arcs return. South North Credit: University of Alaska, Fairbanks. cgabrielse@ucla.edu GEM Student Day, 2013 June 16

  20. The “Auroral Substorm” T=0. Quiet arcs drift equatorward. T=0-5 min. Onset: Sudden brightening of equatorward arc in premidnight sector T=5-10 min. Expansion Phase: Bright, dynamic auroral bulge forms T=10-30 min. Westward-traveling surgeOmega bands form to the east T=30-60 min. Pulsating patches appear at eastern equatorward edge T= 1-2 hours. Recovery phase: Pulsating patches continue as auroral activity dims and quiet arcs return South North Credit: University of Alaska, Fairbanks. cgabrielse@ucla.edu GEM Student Day, 2013 June 16

  21. The “Auroral Substorm” T=0. Quiet arcs drift equatorward. T=0-5 min. Onset: Sudden brightening of equatorward arc in premidnight sector T=5-10 min. Expansion Phase: Bright, dynamic auroral bulge forms T=10-30 min. Westward-traveling surgeOmega bands form to the east T=30-60 min. Pulsating patches appear at eastern equatorward edge T= 1-2 hours. Recovery phase: Pulsating patches continue as auroral activity dims and quiet arcs return South North Credit: University of Alaska, Fairbanks. cgabrielse@ucla.edu GEM Student Day, 2013 June 16

  22. Sun’s magnetic field lines Sun’s magnetic field lines reconnect to Earth’s and pulls them back. Plasma sheet: dense region of plasma where acceleration and transport takes place Reconnection occurs Earth’s magnetic field lines From Øieroset et al, 2001 cgabrielse@ucla.edu GEM Student Day, 2013 June 16

  23. Substorms in Space NENL Modified from Shiokawa [1998] • NENL=Near-Earth Neutral Line (X-line) • A localized phenomenon • Bursty bulk flows (BBFs) only few RE wide Plasmoid Modified from Hones [1977] cgabrielse@ucla.edu GEM Student Day, 2013 June 16

  24. Substorms in Space Fast flow from reconnection Red=strong flow AE [nT] Psuedobreakup E -8RE B [nT] B Vz V [km/s] Tail stretching Dipolarization Y Vy Vx E mV/m Depleted flux tube 8RE Ni [1/cc] X E -23RE -8RE From Figure 5 in Birn et al. [2011] eV eV Particle InjectionsChorusPulsating aurora Bursty Bulk Flows (BBFs)

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