| Autor: |
Wang, Chih‐Ping1 (AUTHOR) cat@atmos.ucla.edu, Wang, Xueyi2 (AUTHOR), Lin, Yu2 (AUTHOR), Mouikis, C. G.3 (AUTHOR), Masson, Arnaud4 (AUTHOR) |
| Předmět: |
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| Zdroj: |
Journal of Geophysical Research. Space Physics. Sep2024, Vol. 129 Issue 9, p1-15. 15p. |
| Abstrakt: |
We conduct a global hybrid simulation of an observation event to affirm that an interplanetary (IP) shock can drive significant suprathermal (tens to hundreds of eV) H+ outflows from the polar cap. The event showed that a spacecraft in the lobe at ∼6.5 RE altitude above the polar cap observed the appearance of suprathermal outflowing H+ ions about 8 min after observing enhanced downward DC Poynting fluxes caused by the shock impact. The simulation includes H+ ions from both the solar wind and the ionospheric sources. The cusp/mantle region can be accessed by ions from both sources, but only the outflow ions can get into the lobe. Despite that upward flowing solar wind ions can be seen within part of the cusp/mantle region and their locations undergo large transient changes in response to the magnetosphere compression caused by the shock impact, the simulation rules out the possibility that the observed outflowing H+ ions was due to the spacecraft encountering the moving cusp/mantle. On the other hand, the enhanced downward DC Poynting fluxes caused by the shock impact drive more upward suprathermal outflows, which reach higher altitudes a few minutes later, explaining the observed time delay. Also, these simulated outflowing ions become highly field‐aligned in the upward direction at high altitudes, consistent with the observed energy and pitch‐angle distributions. This simulation‐observation comparison study provides us the physical understanding of the suprathermal outflow H+ ions coming up from the polar cap. Key Points: A global hybrid simulation to understand the suprathermal outflowing H+ ions observed in southern lobe driven by an interplanetary shockThe simulated outflowing H+ ions in the lobe are outflows from the polar cap driven by enhanced Poynting fluxes caused by the shock impactThe simulated outflowing H+ ions can account for the observed pitch‐angle distribution and the time delay from the shock impact [ABSTRACT FROM AUTHOR] |
| Databáze: |
GreenFILE |
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