A theoretical study of magnetosphere-ionosphere coupling processes

Thesis/Dissertation · Tue Jan 01 04:00:00 EST 1991

OSTI ID:7044575

Cao, Fei

Magnetosphere and ionosphere are coupled electrodynamically by waves, field aligned currents and parallel electric fields. Several fundamental coupling processes are addressed. It is shown that the Alfven wave is the dominant mode in transmitting field aligned currents. Therefore, dynamic M-I coupling can be modeled by the Alfven wave bouncing between the ionosphere and magnetospheric boundaries. The open magnetopause, separating the solar wind and the magnetosphere, behaves like a near perfect reflector to the Alfven wave because of the large solar wind inertia. At the plasma sheet, however, the reflection coefficient may extend over a wide range, depending on the location in the plasma sheet. As the Alfven wave propagates back and forth between the magnetosphere and ionosphere, the field aligned current density increases dramatically at certain locations, especially near the head of the westward traveling surge, causing potential drops to develop along magnetic field lines. It is found that the existence of parallel potential drops can distort the global convection pattern and limit the upward field aligned current. The magnetic reconnection at the dayside magnetopause is responsible for enhancing the convection in the magnetosphere, which subsequently propagates toward the ionosphere by the Alfven wave. The patchy and intermittent reconnection at the dayside magnetopause can be initiated by the 3-D tearing instability, leading to the isolated magnetic islands and X line segments. The nonlinear evolution of tearing in terms of the magnetic island coalescence is also studied.

• Research Organization: Alaska Univ., Fairbanks, AK (United States)
• OSTI ID: 7044575
• Country of Publication: United States
• Language: English

Related Subjects

661320* -- Auroral
Ionospheric
& Magnetospheric Phenomena-- (1992-)
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
CURRENT DENSITY
CURRENTS
EARTH ATMOSPHERE
EARTH MAGNETOSPHERE
ELECTRIC CURRENTS
ELECTRIC FIELDS
HYDROMAGNETIC WAVES
INSTABILITY
INTERACTIONS
IONOSPHERE
MAGNETIC FIELDS
MAGNETIC RECONNECTION
MAGNETOPAUSE
PLANETARY IONOSPHERES
PLASMA INSTABILITY
PLASMA MACROINSTABILITIES
SOLAR ACTIVITY
SOLAR WIND
TEARING INSTABILITY
WAVE PROPAGATION