Magnetosphere‐Ionosphere‐Thermosphere (M‐I‐T) Coupling Leading to Equatorial Upward and Westward Drifting Supersonic Plasma Bubble Development and Amplified Subauroral Polarization Streams (SAPS) During the January 21, 2005 Moderate Storm

Abstract

Significant electric (E) fields are generated under magnetically active conditions in the coupled Magnetosphere-Ionosphere-Thermosphere (M-I-T) system. These E fields include the prompt penetration E field (PPEF), the subauroral E field (SAEF), and the disturbance dynamo (DD) E field (DDEF).Under the control of the interplanetary electric field (IEF), the southward (B Z < 0) interplanetary magnetic field (IMF) reconnects with the magnetospheric magnetic field and drives the magnetospheric convection appearing in the ionosphere as a two-cell polar convection (Dungey, 1961). Before shielding builds up (i.e., during undershielding), the duskward IEF penetrates to the ionosphere as a PPEF with a dayside eastward and nightside westward polarity (Vasyliunas et al., 1970(Vasyliunas et al., , 1972. However, the PPEF can also be produced by solar wind pressure enhancements (C.-S. . The duskward IEF modulates both the two-cell polar convection and the disturbance polar type 2 (DP2) ionospheric currents. The DP2 currents are composed of Hall currents, which form a two-cell Hall current pattern that is anti-parallel to the twocell polar convection pattern (Nishida, 1968). The source of undershielding is the IMF B Z < 0 and/or the domination of region 1 (R1) field-aligned currents (FACs), R1 > R2, which remains effective until the plasmasphere becomes electrically shielded (Jaggi & Wolf, 1973;Vasyliunas, 1972). Oppositely, when the IMF suddenly turns northward (B Z > 0), the duskward magnetospheric convection E field suddenly decreases. Thus, the dawnward shielding E field becomes stronger in the inner magnetosphere creating overshielding (R1 < R2), which is associated with R2 FACs (Wei et al., 2015). The dawnward shielding E field's source is

Signatures of Equatorial Plasma Bubbles and Ionospheric Scintillations from Magnetometer and GNSS Observations in the Indian Longitudes during the Space Weather Events of Early September 2017

“…On 8 September, the seeds of EPBs in the post-sunset period were prompted by a sudden flipping of a reverse EEJ current to an enhanced positive EEJ current, peaking at around 13:00 UT, referring to the local sunset terminator over the Indian longitude sector. This was indeed stimulated by the enhancement in the Ey by the southward turning of Bz and the negative departure of the SYMH, imitating a PRE scenario during the local evening hours on the day [3,4,42]. In fact, the interplay between the PPEF (increased) corresponding to the symmetric ring current and the DDEF (decreased) corresponding to the partial ring current, resulted in a dominant eastward electric field to satisfy the PRE condition [70].…”

“…The coronal mass ejections and solar wind interaction with the earth's magnetosphere can cause severe ionospheric irregularities by introducing scintillations in the signals through plasma depletions associated with the equatorial plasma bubbles (EPBs) [1]. Geomagnetic storms may occur during the southward polarity of the interplanetary magnetic field (Bz) that manipulates the regular equatorial electric fields to trigger pre-reversal enhancements (PREs) to seed the generation and development of plasma bubbles [2][3][4]. Additionally, the substorms formed at the polar latitudes can alter the equatorial electric field during the recovery of geomagnetic storms resulting in an increase or decrease in the scintillation activity [5][6][7][8].…”

Uncovering the Drivers of Responsive Ionospheric Dynamics to Severe Space Weather Conditions: A Coordinated Multi‐Instrumental Approach

“…The occurrence of plasma depletions during geomagnetic storms seems to be associated with sudden upward E × B drifts generated by strong eastward electric field perturbations. But the E × B drift developed within the plasma bubble is due to the interaction of the polarization E field developed due to gravitational Rayleigh‐Taylor (R‐T) plasma instability and the magnetic B field underlying the plasma bubble (Woodman & La Hoz, 1976; Fejer & Kelley, 1980; Li et al., 2021; Horvath & Lovell, 2021). The generalized R‐T instability has been widely accepted as the physical mechanism responsible for the generation of EPBs (Li et al., 2021).…”