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Daytime Aurora

Daytime Aurora. Jøran Moen. (Newell ann Meng, 1992). Dayside Magnetospheric Boundary Layers. (Siscoe. 1991).

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Daytime Aurora

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  1. Daytime Aurora Jøran Moen

  2. (Newell ann Meng, 1992) Dayside Magnetospheric Boundary Layers (Siscoe. 1991) Dayside magnetospheric boundary layers form adjacent to the magnetopause at the inner side. The dayside boyndaries are named Low-latitude boundary layer (largest surface against the solar wind), the cusp (most direct entry for shocked solar wind plasma, and plasma mantle (also called the high latitude boundary layer) The above figure shows a statistical survey of plasma precipitation regions observed by DMSPsatellites at 850 km altitude. The classification scheme is based electron and ion energy spectra and fluxes in the 32 eV-32 keV energy range.

  3. BPS/LLBL/Cusp transitions The MSP observations from Longyearbyen ion the rights, shows a transition from green-dominated aurora (577.7 nm) to red-dominated (630.0 nm). The red-dominted is identified as of BPS source (several keV electrons on closed field lines) and the red-dominated as of cusp source (~100 eV electrons on open field lines. Lorentzen and Moen, JGR, 2000

  4. FAST satellite intersection of Cusp aurora • To come Oksavik et al., accepted by Ann. Geophys., 2003 Notice the staircase stepped ion cuso, low energy electrons, field aligned currents signatures (magnetic field deflections) andE-field irregularities in the cusp.

  5. Solar wind driven ionospheric convection Magnetic flux opened by magentopause reconnection convects across the polar cap, followed by tail reconnection and sunward return flow.

  6. Signatures of pulsed magnetopause recoonnection. Notice the equatorward steps and the poleward moving forms. IMF Bz south 5-10 min recurrence time

  7. IMF By asymmetry on the movement of newly reconnected magnetic flux. The thick arrows indicate the magnetic tension for j x B which act to unbend the curved magnetic field lines

  8. IMF controlled convection patterns Notice the IMF By controlled east-west shift in the cusp inflow region during IMF Bz south conditions in favour of magnetopause reconnection. Reiff and Burch, JGR, 1985

  9. IMF-By controlled CUSP reconfiguration The image sequence demonstrates the auroral response to an an IMF By polarity change from negative to positive. The polarity change was associated with a transition from westward moving to eastward moving auroral events, consistent with magnetopause reconnection and the magetic tension force. The time lag from IMF to the ionospheric response was around 15-20 minutes. BX BY BZ Moen et al., GRL, 1999

  10. Moving auroral form NOAA-12 30 keV electron trapping boundary X-line expansion into the 17 MLT sector

  11. Arc crossing Arc crosing

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