Broad plasma depletions detected in the bottomside of the equatorial F region: Simultaneous ROCSAT‐1 and JULIA observations

Abstract

We investigated the association of broad plasma depletions (BPDs) with plasma bubbles and ionospheric uplift in the equatorial F region using the coincident satellite and radar observations over Jicamarca in Peru. BPDs were detected by the first Republic of China satellite (ROCSAT-1) on the nights of 21 and 22 December 2002 during the period of moderate geomagnetic activity. The observations of the Jicamarca Unattended Long-term Investigations of the Ionosphere and Atmosphere radar and an ionosonde showed that the F peak height was lifted above the ROCSAT-1 altitude (600 km) at the times of the BPD detection. The fraction of NO + was substantial at the locations of BPDs. These observations support the association of the BPDs with the ionospheric uplift. However, the absence of large backscatter plumes at the times of the BPD detection indicates that the BPDs were not produced by a single large bubble or a merger of bubbles.

Investigating the Coupled Magnetosphere‐Ionosphere‐Thermosphere (M‐I‐T) System's Responses to the 20 November 2003 Superstorm

“…This is shown with the NO + line plot depicting an up to 3.1% increase within the southern EIA crest and an up to 13.1% increase poleward of the SED feature. As explained by Kil et al (2014), the locally increased NO + content within the bubbles provides evidence that the bubbles originated from the bottomside ionosphere. Thus, the 0% NO + content in the EIA trough region (shaded interval in yellow) provides further evidence that the equatorial plasma was uplifted and the uplifted plasma originated from the upper region of the ionosphere.…”

“…The plasma bubbles detected (shaded intervals in light blue) at the southern EIA crest and poleward of the northern SED features were studied in detail by Kil et al. (2014) reporting the associated increased NO + content. This is shown with the NO + line plot depicting an up to 3.1% increase within the southern EIA crest and an up to 13.1% increase poleward of the SED feature.…”

“…The V HOR line plot shows the close to zero zonal drifts in the EIA trough region, while the V VER line plot illustrates the enhanced upward drift (↑ in red) in the EIA trough region (near the dip equator) and downward drifts at each EIA crest (↓ in blue) and at the northern SED feature (↓ in dark orange). The plasma bubbles detected (shaded intervals in light blue) at the southern EIA crest and poleward of the northern SED features were studied in detail by Kil et al (2014) reporting the associated increased NO + content. This is shown with the NO + line plot depicting an up to 3.1% increase within the southern EIA crest and an up to 13.1% increase poleward of the SED feature.…”

Multi-spectral optical imaging of the spatiotemporal dynamics of ionospheric intermittent turbulence

“…Merging can occur in three different ways: (i) several highly tilted EPDs from adjacent areas form a reconnected EPD structure consisting of several strings 18 ; (ii) reconnection of a branch of an EPD arising from secondary instabilities with an adjacent EPD; 16 (iii) reconnection of a slowing leading EPD, due to the reduction of its zonal drift speed, with another trailing EPD 15 . Broad plasma depletions are wide and deep decreases of plasma density whose longitudinal width is over several hundred kilometres, associated with plasma density reductions of large magnitude, which have been observed by satellites 19 , numerical simulations 18 , incoherent scatter radars 20 , radio-tomography images 21 , and airglow images 15 . Broad plasma depletions can be formed either by the merging of EPDs 15 , 18 , 19 or ionospheric uplift 20 .…”

“…Broad plasma depletions are wide and deep decreases of plasma density whose longitudinal width is over several hundred kilometres, associated with plasma density reductions of large magnitude, which have been observed by satellites 19 , numerical simulations 18 , incoherent scatter radars 20 , radio-tomography images 21 , and airglow images 15 . Broad plasma depletions can be formed either by the merging of EPDs 15 , 18 , 19 or ionospheric uplift 20 .…”