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Geospace Gap: Issues, Strategy, Progress

The Geospace Gap represents a critical zone between the upper boundaries of current models like TING/TIEGCM and the LFM, where significant plasma transport occurs. This unique region facilitates the conversion of electromagnetic power into field-aligned electrons and ion outflows. Ongoing research aims to address gaps in existing models that overlook crucial processes such as collisionless dissipation and ion parallel transport. Collaborative studies focus on developing multifluid models that incorporate subgrid processes, enhancing our understanding of ionospheric dynamics and their impact on global magnetospheric conditions.

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Geospace Gap: Issues, Strategy, Progress

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  1. Geospace Gap:Issues, Strategy, Progress Cosponsored by NASA HTP Lotko - Gap region introduction Lotko - Outflow simulations Melanson - LFM/SuperDARN/Iridium comparisons Murr - GEM Challenge on MI coupling Lyon - Development of Multifluid LFM Wang - Development of CMIT and TING/TIEGCM Merkin - Proposed studies using multifluid LFM/RCM Lotko - Proposed studies using multifluid CMIT

  2. Geospace Gap:Issues, Strategy, Progress • A 1-2 RE spatial “gap” exists between the upper boundary of TING (or TIEGCM) and the lower boundary of (LFM). • The gap is a primary site of plasma transport where electromagnetic power is converted into field-aligned electrons, ion outflows and heat. • Modifications of the ionospheric conductivity by the electron precipitation are included in global MHD models via the “Knight relation”; but other crucial physics is missing: • Collisionless dissipation in the gap region; • Heat flux carried by upward accelerated electrons; • Conductivity depletion in downward current regions; • Ion parallel transport outflowing ions, esp. O+. Issues The mediating transport processes occur on spatial scales smaller than the grid sizes of the LFM and TING/TIEGCM global Challenge: Develop models for subgrid processes using dependent, large-scale variables available from the global models as causal drivers.

  3. The Geospace:Issues, Strategy, Progress Foster et al. ‘05 Plasma Redistribution

  4. The Geospace:Issues, Strategy, Progress Ring Current & Plasma Sheet Composition Nose et al. ‘05

  5. The Geospace:Issues, Strategy, Progress Simulated O+/H+ Outflow into Magnetosphere Winglee et al. ‘02

  6. Geospace Gap:Issues, Strategy, Progress Paschmann et al., ‘03

  7. Geospace Gap:Issues, Strategy, Progress Evans et al., ‘77 Conductivity Modifications

  8. Geospace Gap:Issues, Strategy, Progress 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

  9. Geospace Gap:Issues, Strategy, Progress “Knight” Dissipation • Current-voltage relation in regions of downward field-aligned current†; • Collisionless Joule dissipation and electron energization in Alfvénic regions – mainly cusp and auroral BPS regions; • Ion transport in regions 1 and 3; • Ion outflow model in the polar cap (polar wind). Lennartsson et al. ‘04 Keiling et al. ‘03

  10. Geospace Gap:Issues, Strategy, Progress Zheng et al. ‘05 Cusp & Auroral-Polar Cap Boundary Region EM Power IN  Ions OUT

  11. Geospace Gap:Issues, Strategy, Progress Energy Flux mW/m2 Mean Energy keV J|| A/m2 Alfvén Poynting Flux, mW/m2 Chaston et al. ‘03 Alfvénic Electron Energization Empirical approach? LFM’s large grid annihilates most of the relevant Alfvénic power near its inner boundary

  12. Geospace Gap:Issues, Strategy, Progress FO+ = 2.14x107·S||1.265 Strangeway et al. ‘05 r = 0.721 r = 0.755 Empirical approach to ionospheric outflow

  13. Geospace Gap:Issues, Strategy, Progress OUTFLOW ALGORITHM Outflows in cusp and auroral polar cap boundary

  14. Geospace Gap:Issues, Strategy, Progress IMF Global Effects of O+ Outflow Equatorial plane 0 2 4 1010 O+ / m2-s 6 Northern Outflow 10 No outflow With outflow • Greatest change in lobes and inner magnetosphere • Magnetopause appears more variable 8

  15. Geospace Gap:Issues, Strategy, Progress T > 1 keV  > 0.5 n < 0.2/cm3 P < 0.01 nPa Where does the mass go? Ionospheric effects?

  16. Geospace Gap:Issues, Strategy, Progress

  17. Geospace Gap:Issues, Strategy, Progress Pathways To Upwelling Strangeway et al. ‘05

  18. Geospace Gap:Issues, Strategy, Progress

  19. Geospace Gap:Issues, Strategy, Progress T > 1 keV  > 0.5 n < 0.2/cm3 P < 0.01 nPa Where does the mass go? Ionospheric effects?

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