Relationships between field-aligned currents, electric fields, and particle precipitation as observed by Dynamics Explorer-2

Statistical distribution of abrupt magnetic field variations observed over the polar ionosphere.

“…In some cases, it has been shown that the magnetic and electric field variations are consistent with the effects of rapidly moving field-aligned current (ROBERT et al, 1984). In some other cases, it has been shown that the current density calculated from magnetic field variation is consistent with that calculated from particle data (SUGIURA et al, 1984). There also exist the rapid electric and magnetic fluctuations which are consistent with the propagating Alfven waves (e.g., GURNETT et al, 1984).…”

“…4) could be extraporated toward the small amplitude fluctuations that are always observed in the large scale field-aligned current regions (e.g., SAFLEKOS et al, 1978;IYEMORI et al, 1985). That is, the low-density of large-scale field-aligned currents are the averaged feature of the small-scale high-density current sheets as mentioned by SUGIURA et al (1984). However, our results of analysis is not enough to clarify the physics of the events.…”

“…Such small scale and discrete nature may be the basic property of the field-aligned current which couples the ionosphere and the magnetosphere (e.g., SUGIURA et al, 1984), because the rapid increase of the frequency of detection for smaller amplitude jumps (see Fig. 4) could be extraporated toward the small amplitude fluctuations that are always observed in the large scale field-aligned current regions (e.g., SAFLEKOS et al, 1978;IYEMORI et al, 1985).…”

Experimental study of the formation of inverted-V structures and their stratification using AUREOL-3 observations

“…Variations are similar for the three main structures although for this pass the FAC carried by primary electrons is systematically higher by a factor of 2. Such dierences were already noted by Sugiura et al (1984) and, in the case of A3 measurements, can be due either to diculties in extracting magnetic ®eld variations from a noisy magnetic ®eld signal, or to geomet- Harel et al (1981) and Spiro et al (1982) expressions (red and blue lines, respectively), e proton ux spectrogram, f ion temperature (keV) provided by the ROBE and ION1 instruments rical factors of the electron sensors not being perfectly adjusted. Nevertheless, the currents obtained are of the right order of magnitude when structures of a $100 km scale are considered (Stasiewicz and Potemra, 1998).…”

“…Partial information on the upgoing electron ux in the 100±10 000 eV range is given by an extra sensor (TBE2) and helps to evaluate the upward¯uxes in this energy range. As demonstrated by Sugiura et al (1984) and Homan et al (1985) using DE1/2 satellites, the upward directed current is mainly carried by hot accelerated electrons. Also, in the present work, we adopt the same integration region as in Bosqued et al (1986): the upward directed electron current density is simply obtained by integrating the primary (magnetospheric) electron¯ux in the loss cone, from 0:8 Ã E peak to $22 keV only.…”