Plasma and magnetic field parameters at substorm onsets derived from GEOS 2 observations

Journal Article · Tue Dec 01 04:00:00 EST 1992 · Journal of Geophysical Research; (United States)

DOI:https://doi.org/10.1029/92JA01732· OSTI ID:6821392

Pu, Z Y; Korth, A ^[1]; Kremser, G ^[2]

---

1. Max-Planck-Institut fuer Aeronomie, Katlenburg-Lindau (Germany)
2. Max-Planck-Institut fuer Aeronomie, Katlenburg-Lindau (Germany) Univ. of Oulu (Finland)

Measurements of energetic particles and the geomagnetic field by the geostationary satellite GEOS 2 were used to investigate the plasma and magnetic field parameters at substorm onset. The distribution of energetic ions and electrons are found to be statistically isotropic at the nightside synchronous orbit. The number density and pressure of electrons N[sub e] and P[sub e] are much lower than N[sub i] and P[sub i] of ions. Electrons and ions increase substantially at substorm onset when compared with magnetically quiet days. Earthward pressure gradients of energetic ions with scale length of [approximately] 10 r[sub i] (r[sub i] = ion gyroradius) are commonly observed during the substorm growth phase. The magnetic field lines are stretched out tailward with a curvature radius in the equatorial plane being considerably smaller than that in the dipole field. Plasma [beta] values increase to the order of 1. All these parameters are found to be consistent with the development of the ballooning instability in connection with substorm onsets.

• OSTI ID: 6821392
• Journal Information: Journal of Geophysical Research; (United States), Journal Name: Journal of Geophysical Research; (United States) Vol. 97:A12; ISSN JGREA2; ISSN 0148-0227
• Country of Publication: United States
• Language: English

Related Subjects

661320* -- Auroral
Ionospheric
& Magnetospheric Phenomena-- (1992-)
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
BALLOONING INSTABILITY
ELECTRON DENSITY
ELECTRON TEMPERATURE
GEOMAGNETIC FIELD
INSTABILITY
ION DENSITY
ION TEMPERATURE
MAGNETIC FIELDS
MAGNETIC PROPERTIES
MAGNETIC STORMS
PHYSICAL PROPERTIES
PLASMA DENSITY
PLASMA INSTABILITY
PLASMA MACROINSTABILITIES