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JOURNAL OF GEOPHYSICAL RESEARCH,
VOL. 111,
A03215,
doi:10.1029/2005JA011084,
2006
Magnetospheric convection and thermal ions in the dayside outer magnetosphere
S.-H. Chen
Universities Space Research Association, Columbia, Maryland, USA
T. E. Moore
Heliospheric Physics Branch, NASA Goddard Space Flight Center, Greenbelt, Maryland, USA
Abstract
We have surveyed 3.5 years of Polar Thermal Ion Dynamics Experiment (TIDE) data between 1 January 2000 and 30 June 2003, when
Polar apogee paths (sections of orbits with geocentric distances r > 5 R
E
) were in the dayside outer magnetosphere, to study the spatial distribution of thermal ions and the magnetospheric convection
paths of the thermal ions, as a function of interplanetary magnetic field (IMF) orientation. We have found a dawn-dusk asymmetry
in the occurrence of detectable thermal ions above the instrument threshold. The occurrence rate was significantly higher
at the duskside. The probability of observing thermal ions, particularly at 1300–1600 local time (LT) near the magnetopause,
was >50%, compared with <30% at the dawnside. We interpret the thermal ion events as the result of plasmaspheric drainage
plumes, as observed by IMAGE spacecraft or geosynchronous orbiters. The episodic appearance of the thermal ions in the outer
magnetosphere could be a significant factor for the dynamo process of global magnetospheric convection. The variation of the
convection pattern due to the IMF orientation is consistent with equatorward and poleward reconnection scenarios that superimpose
dayside convection driven by reconnection on top of the background convection driven by a viscous interaction at the magnetopause,
together with the corotation of the magnetospheric plasma with the ionosphere.
Received 16
February
2005;
accepted 4
January
2006;
published 18
March
2006.
Keywords: magnetospheric convection;
reconnection;
thermal ions.
Index Terms: 2740 Magnetospheric Physics: Magnetospheric configuration and dynamics; 2784 Magnetospheric Physics: Solar wind/magnetosphere interactions; 2736 Magnetospheric Physics: Magnetosphere/ionosphere interactions (2431); 2760 Magnetospheric Physics: Plasma convection (2463); 2723 Magnetospheric Physics: Magnetic reconnection (7526, 7835).
Read Full Article (file size: 412927 bytes) Cited by
Citation: Chen, S.-H., and T. E. Moore
(2006),
Magnetospheric convection and thermal ions in the dayside outer magnetosphere,
J. Geophys. Res.,
111,
A03215,
doi:10.1029/2005JA011084.
Copyright 2006 by the American Geophysical Union.
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