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SAPS intensification during substorm recovery: A multi-instrument case study Roman A. Makarevich

SAPS intensification during substorm recovery: A multi-instrument case study Roman A. Makarevich University of Alaska Fairbanks , USA A. C. Kellerman, J. C. Devlin, H. Ye La Trobe University, Australia L. R. Lyons and Y. Nishimura University of California Los Angeles, USA.

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SAPS intensification during substorm recovery: A multi-instrument case study Roman A. Makarevich

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  1. SAPS intensification during substorm recovery: A multi-instrument case study Roman A. Makarevich University of Alaska Fairbanks, USA A. C. Kellerman, J. C. Devlin, H. Ye La Trobe University, Australia L. R. Lyons and Y. Nishimura University of California Los Angeles, USA

  2. Subauroral Polarization Stream

  3. R1 FAC R2 FAC Anderson et al. (1991): Electric Field   Recombination   Density   Conductivity   (Current = const) Electric Field   … Trough Density Latitude Magnetospheric Current Generator

  4. Magnetospheric Voltage Generator

  5. Southwood and Wolf (1978): V = Ed Charge separation d   (Voltage = Ed = const) Electric Field E  Magnetospheric Voltage Generator

  6. Evidence for Generator Scenarios

  7. Timing of Generator Scenarios Objective: investigate timing and causes of major SAPS intensifications

  8. SAPS Event SAID TIG beam 4 UNWbeam 0

  9. SAPS and Substorm Phases Recovery Ground arb units IMAGE UNW SAPS intensification during recovery phase

  10. UNW All Beams UNW all beams UNW keogram

  11. TEC Observations SD FIT GPS TEC SD FIT Vorticity (~FAC)

  12. SAPS and Auroral Precipitation SAPS narrows and separation from precipitation increases

  13. SAPS and TEC Trough Strong 2D association between SAPS and TEC trough

  14. Magnetospheric and Topside Signatures Magnetosphere (LANL, GOES): No parameter was found to exhibit similar time dependence to the SAPS strength during recovery apart from energetic electron fluxes at 01 and 15 MLT (but not at 00 MLT) Topside ionosphere (DMSP IDM): Significant ion upflows Some topside density enhancement

  15. Conclusions • Strong, 2-D association between SAPS and TEC trough was found, but no density decrease during recovery and SAPS intensification • Both voltage and current generator scenarios had difficulties explaining observations • No parameter was found that exhibited similar time dependence to the SAPS intensity, suggesting that it may be triggered, e.g. by convection and auroral bursts

  16. PBI and Convection Burst Some evidence of equatorward motion

  17. SAPS and PBI PBI appears and propagates equatorward

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