Equatorial spread <I>F</I> fossil plumes

Abstract

Abstract. Behaviour of equatorial spread F (ESF) fossil plumes, i.e., ESF plumes that have stopped rising, is examined using the NRL SAMI3/ESF three-dimensional simulation code. We find that fossil bubbles, plasma density depletions associated with fossil plumes, can persist as highaltitude equatorial depletions even while being "blown" by zonal winds. Corresponding airglow-proxy images of fossil plumes, plots of electron density versus longitude and latitude at a constant altitude of 288 km, are shown to partially "fill in" in most cases, beginning with the highest altitude field lines within the plume. Specifically, field lines upon which the E field has fallen entirely to zero are affected and only the low altitude (≤600 km) portion if each field line fills in. This suggests that it should be possible to observe a bubble at high altitude on a field line for which the corresponding airglow image no longer shows a depletion. In all cases ESF plumes stop rising when the flux-tube-integrated ion mass density inside the upper edge of the bubble is equal to that of the nearby background, further supporting the result of Krall et al. (2010b).

Global Distribution of Nighttime Medium‐Scale Traveling Ionospheric Disturbances Seen by Swarm Satellites

“…Plasma bubbles and blobs represent plasma depletions and enhancements, respectively, relative to the ambient plasma density. The creation of plasma blobs in middle latitudes is explained in association with either equatorial plasma bubbles (Huang et al, ; Krall et al, , ; Le et al, ; Martinis et al, ; Yokoyama et al, ) or MSTIDs (Choi et al, ; Kil et al, , ; Miller et al, ), but we do not know yet which mechanism plays a dominant role in the creation of blobs.…”

The story of plumes: the development of a new conceptual framework for understanding magnetosphere and ionosphere coupling

“…In addition, the uplift of the equatorial ionosphere due to enhanced E fields at dusk often sets off plasma instabilities (e.g., Basu et al, 1980;Kelley et al, 2011) that gives rise to low-density bubbles or plumes. Note that in this context the terms bubble and plumes are used to describe low-density regions and the plasma motion associated with these regions (e.g., Bernhardt, 2007;Krall et al, 2010). Some of the small-scale density structures have been suggested to be convected to midlatitudes in the SED plumes, giving rise to midlatitude irregularity as well (e.g., Horvath and Lovell, 2011).…”

Density and Temperature Structure of Equatorial Spread F Plumes

“…In comparing these results to observations [e.g., Tsunoda, 1981], we acknowledge that the idealizations of a single-bubble perturbation and zero wind lead to a maximum bubble height of 1600 km, which is unusual for such low values of the F10.7 and F10.7a indices. Additional simulations indicate that the maximum bubble height is reduced for nonzero winds Huba et al, 2009c] or in cases where multiple bubbles are seeded [Krall et al, 2010c].…”