Super plasma fountain and equatorial ionization anomaly during penetration electric field

Abstract

[1] Relative importance of diffusion, electric field, and neutral wind on equatorial plasma fountain and equatorial ionization anomaly (EIA) during a strong daytime eastward prompt penetration electric field (PPEF) event are evaluated using the Sheffield University Plasmasphere Ionosphere Model and the recorded PPEF during the super geomagnetic storm of 9 November 2004. The fountain rapidly develops into a super fountain during the PPEF event. The super fountain becomes strong with less poleward turning of the velocity vectors in the presence of an equatorward wind that reduces (or stops) the downward velocity component due to diffusion and raises the ionosphere to high altitudes of reduced chemical loss. The EIA crests in peak electron density and total electron content shift rapidly to higher than normal latitudes during the PPEF event. However, the crests become stronger than normal only in the presence of an equatorward wind. The results suggest that the presence of an equatorward neutral wind is required to produce a strong positive ionospheric storm during a daytime eastward PPEF event. The equatorward neutral wind need not be a storm time wind though stronger wind can lead to stronger ionospheric storms.

Mid-latitude Summer Nighttime Anomaly (MSNA) – observations and model simulations

“…This corroborates with the behavior that the MSNA shows significant longitudinal variation, and is enhanced around the Japanese longitudes. The observations as well as simulations confirm the importance of equatorward neutral winds in the formation of MSNA, and the mechanism is similar to the equatorward wind producing positive ionospheric storms (Balan et al, 2009). (3) The HWM-93 wind magnitudes do not realistically represent the meridional wind magnitudes over Japanese longitudes, and hence are insufficient to generate the MSNA feature in the simulations.…”

“…The other factor is that at night, the lifting of ionosphere to higher heights where the recombination rates are less enables the plasma to live longer. These aspects of MSNA indicate the importance of equatorward neutral winds in the formation of MSNA; the mechanism is similar to the equatorward wind producing positive ionospheric storms (Balan et al, 2009). longitude in July 2008 is also plotted.…”

Electrodynamics of ionospheric weather over low latitudes

“…An AE activity with amplitude even as low as ~ 100 nT (in an otherwise quiet condition) has been found to cause penetration electric fields at equatorial region in the form of EEJ modulation of moderate degree, (10-20 nT), and irregularity development in the EEJ (Abdu 2012). Intense and super storms characterized by large changes in the AE activity (and Dst decreases) are known to produce large increases on the dayside and evening sector TEC, with the EIA expanding to higher latitude (Abdu 1997;Tsurutani et al 2004;Mannucci et al 2005;Lin et al 2005;Balan et al 2009). Such redistribution of enhanced low latitude plasma associated with storm time super fountain due to penetration electric field has been invoked to explain the storm-enhanced density (SED) plume phenomenon observed at mid-latitudes in the American longitudes (Foster et al 2005) as well as in Asia longitude (Maruyama 2006), but with larger amplitude in the American longitude sector that has been attributed to the influence of the South Atlantic Magnetic Anomaly (SAMA) (Foster et al 2005) where Abdu et al 2008 observed abnormally large storm time penetration electric field.…”

First storm‐time plasma velocity estimates from high‐resolution ionospheric data assimilation

“…Physics-based modeling of the positive ionospheric storm has been conducted [Lin and Yeh, 2005;Lekshmi et al, 2008;Lu et al, 2012Lu et al, , 2013. Balan et al [2009Balan et al [ , 2010Balan et al [ , 2011Balan et al [ , 2013 have shown that storm time electric fields alone cannot produce SEDs but that storm time neutral winds alone or in combination with electric fields can do so. The physics of the SED remains an active area of scientific study.…”