Strong induction effects during the substorm on 27 August 2001

Abstract

We report on strong induction effects notably contributing to the cross polar cap potential drop and the energy balance during the growth and active phases of the substorm on 27 August 2001. The inductance of the magnetosphere is found to be crucial for the energy balance and electrical features of the magnetosphere in the course of the substorm. The inductive response to the switching on and off of the solar wind-magnetosphere generator exceeds the effect of the interplanetary magnetic field (IMF) variation. The induction effects are most apparent during the substorm expansion onset when the rapid growth of the ionospheric conductivity is accompanied by the fast release of the magnetic energy stored in the magnetotail during the growth phase. Using the magnetogram inversion technique, we estimated the magnetospheric inductance and effective ionospheric conductivity during the loading and unloading phases.

Effects of the interplanetary magnetic field on the location of the open‐closed field line boundary

“…Another method is the magnetogram inversion technique [ Mishin , ; Kamide and Baumjohann , ], which calculates electric potential, field‐aligned current, and equivalent current using the long‐period variable geomagnetic field in the polar region as input. In this method, the high‐latitude boundary of Region‐1 FAC is considered as the OCB [e.g., Mishin et al , , ]. In addition, the sophisticated MHD simulations can be used to describe the solar wind‐magnetosphere interaction, thus can also make it possible to look at the character of the OCB in global scales [e.g., Lopez et al , ; Kabin et al , ; Rae et al , , ; Wang et al , ].…”

27 August 2001 substorm: Preonset phenomena, two main onsets, field‐aligned current systems, and plasma flow channels in the ionosphere and in the magnetosphere

“…EO1 observed in the R1− cell was assumed to be produced, in part, by evolution of this instability [e.g., Atkinson , ; Holzer and Sato , ; Sato , ; Fujii and Iijima , ; Lysak , ; Newell et al , ; Liou et al , ; Korth et al , ; Marsal , ]. The evidence of such an instability and EO1 created by it is (1) a spontaneous growth in the upward FAC intensity I R 1− and (2) a simultaneous sharp increase in the ionosphere conductivity Σ eff (see Figure b and its discussion in section 2.3.1, also Mishin et al [, Figure 3] and Mishin et al [, Figure 5].…”

“…Then, we have a characteristic time of the magnetic energy accumulation in lobes, . This time corresponds to the duration of the main energy part accumulation during the considered substorm growth phase [ Mishin et al , ]. The magnetic energy of the described current couple in tail lobes is Δ W = 2(Δ B ) 2 SL /(2 μ 0 ) ≈ 6.4 ∙ 10 13 J. In the MR2 reconnection process for the Δ t ~ 20 min expansion phase, this energy is transformed into the electric energy of the MR2 generator.…”

Special issue “Coupling of the high and mid latitude ionosphere and its relation to geospace dynamics”

“…The inductive effects of the magnetosphere during the course of a substorm have been studied by Mishin et al (2015).…”