太陽風磁場変動と磁気圏境界

概要

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Interplanetary magnetic field (IMF) effects on the low latitude dayside magnetopause are examined on the basis of GEOTAIL and WIND satellite data. The GEOTALL satellite skimmed through low dayside magnetopause and the WIND satellite monitored solar wind at a distance of about 70 Re upstream from the Earth. It reveals that the structure of dayside magnetopause at low latitude sensitively depends on the IMF Bz conditions. The dayside magnetopause consists of two different plasma layers, i. e., inner and outer boundary layers. The inner boundary layer consists of 5∿10 keV ions, while the outer boundary layer consists of much lower energy ions with 1∿3 KeV mixing with ions of the magnetosheath. Another important finding is that impulsive fluctuations of magnetic field intensity and plasma density are frequently observed in the boundary layers. They occur quasi-periodically with an interval of 3∿8 minutes. The signatures of the impulses suggest some evidences of magnetic field reconnection between the Earth's magnetic field and the IMF. The quasi-periodicity in the occurrence of the impulse may be attributed to undulations in the boundary layer excited by the Kelvin-Helmholtz instability.
東海大学の論文