Relationship of upflowing ion beams and conics around the dayside cusp/cleft region to the interplanetary conditions

W Miyake,T Mukai,N Kaya

doi:10.5194/angeo-20-471-2002

W Miyake, T Mukai + Show 1 more

Open Access

https://doi.org/10.5194/angeo-20-471-2002

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Abstract

Abstract. The dayside cusp/cleft region is known as a major source of upflowing ionospheric ions to the magnetosphere. Since the ions are supposed to be energized by an input of energy from the dayside magnetospheric boundary region, we examined the possible influence of the interplanetary conditions on dayside ion beams and conics observed by the polar-orbiting Exos-D (Akebono) satellite. We found that both the solar wind velocity and density, as well as IMF By and Bz , affect the occurrence frequency of ion conics. The energy of ion conics also depends on the solar wind velocity, IMF By and Bz . The ion beams around the local noon are not significantly controlled by the interplanetary conditions. The results reveal that ion convection, as well as the energy source, is important to understand the production of dayside ion conics while that of ion beams basically reflects the intensity of local field-aligned currents.Key words. Ionosphere (particle acceleration) – magnetospheric physics (magnetopause, cusp, and boundary layers; magnetosphere ionosphere interaction)

Highlights

The dayside cusp/cleft region is known as a major source of ion conics (Gorney et al, 1981; Kondo et al, 1990; Thelin et al, 1990; Miyake et al, 1996), as well as low-energy upwelling ions (e.g. Lockwood et al, 1985; Yau and Andre, 1997)
The energy of ion beams is defined as the energy of the field-aligned peak of ion flux, while that of ion conics is the maximum energy observed of conical ion distributions
It is revealed that the occurrence frequency of dayside ion conics are controlled by most of the interplanetary parameters; IMF By and Bz, solar wind velocity and density, while that of dayside ion beams shows little dependence on them

Summary

Introduction

The dayside cusp/cleft region is known as a major source of ion conics (Gorney et al, 1981; Kondo et al, 1990; Thelin et al, 1990; Miyake et al, 1996), as well as low-energy upwelling ions (e.g. Lockwood et al, 1985; Yau and Andre, 1997). The dayside cusp/cleft region is known as a major source of ion conics (Gorney et al, 1981; Kondo et al, 1990; Thelin et al, 1990; Miyake et al, 1996), as well as low-energy upwelling ions Lockwood et al, 1985; Yau and Andre, 1997). Various energy mechanisms and sources have been proposed (Andre and Yau, 1997). Interplanetary magnetic field and solar wind plasma conditions control the cusp geometry and dynamics of particles and fields around the cusp/cleft region (see, for example, Smith and Lockwood, 1996) and are supposed to control the dayside ion energization. Lennartsson (1995) found the ionospheric oxygen ion density in the plasma sheet to be correlated with solar wind energy flux The energized ions of terrestrial origin are transported to the magnetosphere and are believed to be an important source of plasma populations in the magnetotail (e.g. Chappell, 1988). Lennartsson (1995) found the ionospheric oxygen ion density in the plasma sheet to be correlated with solar wind energy flux

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