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Properties and origin of energetic particles at the duskside of the Earth’s magnetosheath throughout a great storm (1999)

Sarafopoulos, D. V. ; Athanasiu, M. A. ; Sarris, E. T. ; [et al.]

Springer

Annales geophysicae 17 (1999), S. 1121-1133

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ISSN: 0992-7689

Keywords: Magnetospheric physics (magnetosheath; magnetotail boundary layers; storms and substorms)

Source: Springer Online Journal Archives 1860-2000

Topics: Geosciences , Physics

Notes: Abstract We study an interval of 56 h on January 16 to 18, 1995, during which the GEOTAIL spacecraft traversed the duskside magnetosheath from X ≅ −15 to −40 RE and the EPIC/ICS and EPIC/STICS sensors sporadically detected tens of energetic particle bursts. This interval coincides with the expansion and growth of a great geomagnetic storm. The flux bursts are strongly dependent on the magnetic field orientation. They switch on whenever the Bz component approaches zero (Bz ≅ 0 nT). We strongly suggest a magnetospheric origin for the energetic ions and electrons streaming along these “exodus channels”. The time profiles for energetic protons and “tracer” O+ ions are nearly identical, which suggests a common source. We suggest that the particles leak out of the magnetosphere all the time and that when the magnetosheath magnetic field connects the spacecraft to the magnetotail, they stream away to be observed by the GEOTAIL sensors. The energetic electron fluxes are not observed as commonly as the ions, indicating that their source is more limited in extent. In one case study the magnetosheath magnetic field lines are draped around the magnetopause within the YZ plane and a dispersed structure for peak fluxes of different species is detected and interpreted as evidence for energetic electrons leaking out from the dawn LLBL and then being channelled along the draped magnetic field lines over the magnetopause. Protons leak from the equatorial dusk LLBL and this spatial differentiation between electron and proton sources results in the observed dispersion. A gradient of energetic proton intensities toward the ZGSM= 0 plane is inferred. There is a permanent layer of energetic particles adjacent to the magnetosheath during this interval in which the dominant component of the magnetic field was Bz.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/s00585-999-1121-2

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Harmonics of 60 Hz in power systems caused by geomagnetic disturbances (1979)

Tsuruda, K. ; Hayashi, K. ; Horita, R. E. ; [et al.]

In: CASI

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Publication Date: 2006-01-16

Description: Simultaneous VLF/ULF observations carried out near Winnipeg, Manitoba show that geomagnetic disturbances control the behavior of harmonics of 60 Hz man-made electric power. The harmonics of 60 Hz detected by the VLF receiver are at multiples of 180 Hz, indicating that they originated from a 3 phase ac power system. Under geomagnetically quiet conditions, only odd harmonics of 70 Hz were detected. In disturbed conditions, both odd and even harmonics were excited. The strength of each harmonic changed concurrently with geomagnetic pulsation (ULF) activity. These findings seem to indicate that a portion of telluric currents shunted into the power line system through the neutrals of the Y-connected transformers give rise to a dc bias to the transformer core materials and that it distorts their hysteresis loops, activating harmonics of 60 Hz power. A mathematical proof is given that a hysteresis loop having a point of symmetry generates odd harmonics only, whereas loops lacking in point-symmetry generally give rise to both odd and even harmonics. A general formula was obtained to calculate the strength of each harmonic based on the shape of the hysteresis loop.

Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING

Type: NASA. Marshall Space Flight Center Solar-Terrest. Predictions Proc., Vol. 2; p 172-181

Format: text

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