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M AGNETOSPHERE -I ONOSPHERE C OUPLING M ORE I S D IFFERENT

M AGNETOSPHERE -I ONOSPHERE C OUPLING M ORE I S D IFFERENT. William Lotko, Dartmouth College. System perspective  qualitative differences Life cycle of an ionospheric O + plasma element Creation & Evolution Transport & Fate Impacts Reconciling models with measurements.

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M AGNETOSPHERE -I ONOSPHERE C OUPLING M ORE I S D IFFERENT

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  1. MAGNETOSPHERE-IONOSPHERE COUPLING MORE IS DIFFERENT William Lotko, Dartmouth College • System perspective  qualitative differences • Life cycle of an ionospheric O+ plasma element • Creation & Evolution • Transport & Fate • Impacts • Reconciling models with measurements

  2. 1730 UT 30º Lat 20 Nov 2003 Foster et al. ‘05

  3. 1820 UT 30º Lat 20 Nov 2003 Foster et al. ‘05

  4. 1945 UT CUSP POLAR WIND Downward J|| BPS Downward J|| 30º Lat 20 Nov 2003 Foster et al. ‘05

  5. CUSP Midlatitude plume + Electron precipitation + Alfvénic Poynting flux  O+ outflow 30º Lat cf. Strangeway et al. ‘05 Zheng et al. ‘05

  6. 1945 UT BPS 30º Lat 20 Nov 2003 Foster et al. ‘05

  7. Auroral BPS • Patch/Plume Dynamics • Convects across CRB • Upward Vi const • before, during, after • The enhancement produces massive • upflux as it drifts • through the Boundary Plasma Sheet region. Semeter et al. ‘03

  8. Auroral BPS Alfvénic Poynting Fluxes Statistical Distributions Keiling et al. ‘03 Polar satellite data

  9. Auroral BPS • Intense Alfvén waves • Superthermal electrons • Ion  heating • Massive outflows • How is the Alfvénic power converted to ion heat? • ICRH • BBELF • coherent energization • stochastic energization What regulates the outflow mass flux? Chaston et al. ‘03

  10. Auroral BPS Outflow in other auroral-zone regions Paschmann et al. ‘03

  11. 1945 UT Downward J|| Downward J|| 30º Lat 20 Nov 2003 Foster et al. ‘05

  12. Downward Currents • BBELF turbulence • Superthermal electrons • Filamentary J|| • Ion  heating • Downward E|| •  “pressure cooker” • Large outflows, but limited • by downward E|| Lynch et al. ‘02

  13. Active Ionization and Depletion Evans et al. ‘77

  14. Auroral Electrodynamics Opgenoorth et al. ‘02

  15. Alfvén Wave Intensification Feedback Instability in the Ionospheric Alfvén Resonator equator J|| ENS 8.25 L = 7.25 ionosphere t = 0 s -5 A/m2 • Conditions • Low-conductivity E region • Large-scale downward J|| • Large-scale intense E • Strong  gradient in P • Effects • Reduced Joule dissipation • Filamentary J|| • 1-10 km -scale turbulence • Enhanced outflow • Superthermal, bidirectional e 31 s 62 s 93 s 637 mV/m 124 s -36 A/m2 Streltsov and Lotko ‘04

  16. Streltsov and Lotko ‘04

  17. Simulated Time Variation of Ne Profile in Downward Current Region Cavity formation on bottomside is more efficient than at F-region peak  Bottomside gradient steepens Doe et al. ‘95

  18. FATE • Plasmasheet • Normally H+ dominant • O+-rich during storms • O+ injections from Cusp fountain Nightside BPS • Stormtime substorms • H+ is swept away • Leaving O+ dominant pressure and density • Earthward injected O+ dominates ring current Kistler et al. ‘05

  19. FATE Ring Current & Plasma Sheet Composition Nose et al. ‘05

  20. IMPACT Simulated O+/H+ Outflow into Magnetosphere Winglee et al. ‘02

  21. Feedback Instability IAR Modes 1 min 1-10 s < 10 km Ion Outflow ~ 10 min Patch Dynamics Bottomside Depletion 10 s Cavity Formation

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