Plasmaspheric dynamics resulting from the Hallowe'en2003 geomagnetic storms

摘要

Cross-phase-derived plasma mass density trends during the Hallowe'en 2003geomagnetic, storms are presented for 38° S magnetic latitude S 63° (1.61 < L < 5.10),using data from the SAMNET (Subauroral Magnetometer Network), BGS (BritishGeological Survey), and SEGMA (South European Geomagnetic Array), ground-basedmagnetometer arrays in Europe. At all latitudes monitored, a rapid increase of total massdensity is observed immediately following the initial storm sudden commencement at0611 UT on 29 October, believed to be due to rapid ionospheric 0+ outflow.Plasmaspheric density depletion to at least 50° magnetic latitude (L 2.4) took place overthe next 3 days. Poststorm refilling began on 2 November. Following the suddencommencement of another storm on 4 November, a density enhancement wasmonitored at 2.79 < L < 3.84, with subsequent plasmaspheric depletion occurring by6 November. Plasma mass density values are compared to empirical plasmapause locationmodel predictions, with reasonable agreement for most days, but density depletion andrefilling were monitored 1 day after they are predicted. During poststorm plasmasphericrefilling, some extremely low early morning resonance frequencies are monitored andappear be due to quarter mode standing waves. This study also highlights that care must betaken in the choice of assumed geomagnetic field geometry when deriving plasma massdensities from observed field line resonances during severe geomagnetic storms.