Relationship between auroral substorm and ion upflow in the nightside polar ionosphere

Abstract

[1] We investigated ionospheric ion upflow during an auroral substorm using simultaneous European Incoherent Scatter radar and IMAGE satellite data. Approximately 6 min after an initial brightening identified with data from the IMAGE wideband imaging camera instrument, ion upflow was seen and the electron temperature became enhanced, too. The ion upflow, with a velocity of about 150 m/s, and the electron temperature enhancement lasted for about 25 min. During the poleward expansion phase, surges of large upward ion velocity and flux, and high ion and electron temperatures occurred over Longyearbyen. The upward ion flux reached 2 × 10 14 m À2 s À1. Naturally enhanced ion-acoustic lines (NEIALs) were seen near the poleward edge of the expanded auroral oval both near the end of expansion phase 17 min after onset and also later in the recovery phase. The NEIALs seemed to be accompanied by another type of enhanced echoes, obliquely to the local geomagnetic field. Data from the Low Energy Neutral Atom instrument on the IMAGE satellite show that energetic neutral oxygen reaches the IMAGE satellite about 40 min after the initial brightening, and oxygen continues to get detected during the recovery phase. We propose that ion upflow at the poleward edge of the auroral oval during the expansion phase is related to ion/neutral outflow with energy below 18-27 eV, whereas during the recovery phase of a substorm upward ions are accelerated up to about 60 eV and flow out in the entire polar region.

Characteristics of CME‐ and CIR‐Driven Ion Upflows in the Polar Ionosphere

“…The upflows would be mainly caused by frictional heating in the F region ionosphere near the poleward edge of auroral oval. The case study by Ogawa et al (2013) clearly shows such large upflows at the northward edge of aurora during the poleward expansion of auroral substorm. This study indicates that upward flux at this latitude becomes significant in nighttime during the first day of storms, although its velocity becomes small on average.…”

“…In the polar ionosphere, ion upflow is frequently seen during auroral substorm (e.g., Ogawa et al, ), which is most likely associated with the ion outflow measured in the bottomside magnetosphere (Wilson et al, ). A typical duration of a substorm is about a few hours.…”

Damped Kadomtsev Petviashvilli equation for magnetosonic waves in a dissipative OH plasma in the ionospheric F-Layer

“…In subsequent years the existence of multi-ion plasmas has been confirmed by various satellite (e.g. Viking, Freja, IMAGE) observations [4]. The F-layer of the terrestrial ionosphere which consists of various gases such as N , 2 O , 2 and atomic oxygen undergoes ionization due to ultraviolet radiation emanating from the Sun.…”

Flux Enhancements of Field‐Aligned Low‐Energy O+ Ion (FALEO) in the Inner Magnetosphere: A Possible Source of Warm Plasma Cloak and Oxygen Torus

“…(2009) found that ion outflow is delayed by several minutes from storm time substorms; and Ogawa et al. (2013) reported that ion upflow occurs about 6 min after the auroral initial brightening. From these assumptions, the test O + ions are released at t delay after 05:24 UT, where t delay is expressed as $$${t}_{\text{delay}}[\mathrm{min}]=10[\mathrm{min}\text{/hr}]\times \vert {\text{MLT}}_{j}[\mathrm{hr}]-23.8[\mathrm{hr}]\vert +10[\mathrm{min}/L]\times \left({L}_{i}-5.0\right)+3[\mathrm{min}].$$$ Therefore, t delay ranges from 3 min at ( L , MLT) = (5.0, 23.8 hr) to 15 min at ( L , MLT) = (5.4, 23.0 hr) and (5.4, 0.6 hr), indicating that the release time of O + ions is between 05:27 UT and 05:39 UT.…”