Storm‐Enhanced Development of Postsunset Equatorial Plasma Bubbles Around the Meridian 120°E/60°W on 7–8 September 2017

Li, Guozhu; Ning, Baiqi; Wang, Chi; Abdu, M. A.; Otsuka, Yuichi; Yamamoto, M.; Wu, Jian; Chen, Jinsong

doi:10.1029/2018ja025871

Cited by 71 publications

(77 citation statements)

References 41 publications

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“…The dark streaks that cut through the EIA band represent reduced emissions caused by low density within plasma bubbles. The airglow signature of EPBs and the tilted structure were also illustrated in simulations (Retterer, 2010) and are consistent with the previous ground-based and spaceborne observations (Jin et al, 2018;Kelley et al, 2003;Kil et al, 2009;Li et al, 2018;Tsunoda et al, 1982), which will be further discussed in the next section. These streaks elongate from northwest to southeast direction, with a meridional length of ∼1,500-2,000 km and interbubble distance of ∼500-800 km.…”

Section: Resultssupporting

confidence: 86%

Coordinated Ground‐Based and Space‐Based Observations of Equatorial Plasma Bubbles

Zou

Eastes

et al. 2020

JGR Space Physics

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This paper presents coordinated and fortuitous ground-based and spaceborne observations of equatorial plasma bubbles (EPBs) over the South American area on 24 October 2018, combining the following measurements: Global-scale Observations of Limb and Disk far ultraviolet emission images, Global Navigation Satellite System total electron content data, Swarm in situ plasma density observations, ionosonde virtual height and drift data, and cloud brightness temperature data. The new observations from the Global-scale Observations of Limb and Disk/ultraviolet imaging spectrograph taken at geostationary orbit provide a unique opportunity to image the evolution of plasma bubbles near the F peak height over a large geographic area from a fixed longitude location. The combined multi-instrument measurements provide a more integrated and comprehensive way to study the morphological structure, development, and seeding mechanism of EPBs. The main results of this study are as follows: (1) The bubbles developed a westward tilted structure with 10-15 • inclination relative to the local geomagnetic field lines, with eastward drift velocity of 80-120 m/s near the magnetic equator that gradually decreased with increasing altitude/latitude. (2) Wave-like oscillations in the bottomside F layer and detrended total electron content were observed, which are probably due to upward propagating atmospheric gravity waves. The wavelength based on the medium-scale traveling ionospheric disturbance signature was consistent with the interbubble distance of ∼500-800 km. (3) The atmospheric gravity waves that originated from tropospheric convective zone are likely to play an important role in seeding the development of this equatorial EPBs event.Plain Language Summary This study presents multi-instrument observations of equatorial plasma density depletions occurred on 24 October 2018 by using Global-scale Observations of Limb and Disk far ultraviolet images, Global Navigation Satellite System total electron content data, electron density measurements from Swarm satellite, ionosonde measurements, and cloud temperature data. This multi-instrument study generated an integrated and detailed image revealing both large-scale and mesoscale structures of the equatorial plasma depletion. Our results also suggest that atmospheric gravity waves originating from tropospheric convection activity could play a significant seeding role in the development of equatorial plasma bubbles. Key Points: • Combined GOLD/UV spectrograph images and ground-based TEC data revealed EPB features and development over a large geographic area • Bottomside F layer oscillations and traveling ionospheric disturbance were observed by ionosonde and detrended TEC results • Atmospheric gravity waves likely play an important role in seeding the R-T instability and the development of this EPB event Correspondence to: E. Aa,

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Section: Resultssupporting

confidence: 86%

Coordinated Ground‐Based and Space‐Based Observations of Equatorial Plasma Bubbles

Zou

Eastes

et al. 2020

JGR Space Physics

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“…The vertical velocity drift over Campo Grande (Figure c) and Sao Luis (Figure e) also displayed considerable increase compared with those on quiet day (6 September). Similar ionosonde measurements were also reported in Li et al (), and these collectively demonstrate the presence of an enhanced equatorial PPEF to trigger EPBs.…”

Section: Discussionsupporting

confidence: 89%

“…The solar wind and IMF conditions during 7–8 September 2017 have been described in several recent papers (e.g., Aa et al, ; Jin et al, ; Lei et al, ; Li et al, ; Shen et al, ), which are also shown here in Figures a–d. It was a storm with a double main phase.…”

Section: Geomagnetic Conditions Of 7–8 September 2017supporting

confidence: 71%

Merging of Storm Time Midlatitude Traveling Ionospheric Disturbances and Equatorial Plasma Bubbles

Zou

Ridley

et al. 2019

Space Weather

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Postsunset midlatitude traveling ionospheric disturbances (TIDs) and equatorial plasma bubbles (EPBs) were simultaneously observed over American sector during the geomagnetic storm on 8 September 2017. The characteristics of TIDs are analyzed by using a combination of the Millstone Hill incoherent scatter radar data and 2‐D detrended total electron content (TEC) from ground‐based Global Navigation Satellite System receivers. The main results associated with EPBs are as follows: (1) stream‐like structures of TEC depletion occurred simultaneously at geomagnetically conjugate points, (2) poleward extension of the TEC irregularities/depletions along the magnetic field lines, (3) severe equatorial and midlatitude electron density (Ne) bite outs observed by Defense Meteorological Satellite Program and Swarm satellites, and (4) enhancements of ionosphere F layer virtual height and vertical drifts observed by equatorial ionosondes near the EPBs initiation region. The stream‐like TEC depletions reached 46° magnetic latitudes that map to an apex altitude of 6,800 km over the magnetic equator using International Geomagnetic Reference Field. The formation of this extended density depletion structure is suggested to be due to the merging between the altitudinal/latitudinal extension of EPBs driven by strong prompt penetration electric field and midlatitude TIDs. Moreover, the poleward portion of the depletion/irregularity drifted westward and reached the equatorward boundary of the ionospheric main trough. This westward drift occurred at the same time as the sudden expansion of the convection pattern and could be attributed to the strong returning westward flow near the subauroral polarization stream region. Other possible mechanisms for the westward tilt are also discussed.

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“…Hence, the PPEF effect might have caused F 2 layer peak to move above the orbiting height of SWA over the equator and diffuse at the low latitudes during this period, indicating an enhanced fountain effect on 8 September in comparison with the other days. The h m F 2 over Guam in Figure 10d of Li et al () which was around the same region with Figure a observed increase above 400 km around 0000 UT indicating the uplift of F 2 layer peak. In Figures b–d, owning to changes in the storm time electric field disturbances, there were Ne depletions at the equatorial/low latitudes on 8 September such that there were times when the Ne on 11 September was higher than on 8 September, which was not as a result of any unusual TEC increase on 11 September.…”

Section: Observationssupporting

confidence: 74%

“…This implies that the ionospheric unusual enhancement in TEC during the recovery phase depends on local times. Figure 6d in Lei et al () showed there was a significant increase in the EEJ on 11 September as compared to the reference over the Asian/Australian sector. At the same time, the geomagnetic activity for this day was relatively quiet, which suggests that the disturbance in the ionospheric electrodynamics of this day could have its source from elsewhere (besides magnetic storm drivers).…”

Section: Discussionmentioning

confidence: 88%

Topside Ionospheric Conditions During the 7–8 September 2017 Geomagnetic Storm

et al. 2019

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The uplooking total electron contents (TECs) from the GRACE, SWARM-A, TerraSAR-X, andMetOp-A satellites and in situ electron density (Ne) from SWARM-A were utilized to investigate the topside ionospheric conditions during the 7-8 September 2017 geomagnetic storm. The rate of TEC index (ROTI) and rate of density index (RODI), which are derivative indices of TEC and Ne, respectively, were also used to characterize the topside ionospheric irregularities. The main results of this study are as follows: (1) There were significant enhancements seen in the uplooking TEC during the first main phase of the storm. (2) The uplooking TEC did not show unusual enhancement at the morning and evening local times in the Asian-Australian sector during the recovery phase of the storm. (3) Prominent TEC hemispheric asymmetry at the middle and high latitudes was observed at both day and night sectors. (4) Long-duration recovery of topside TEC with respect to the prestorm condition was also detected in this event. (5) Nighttime ROTI enhancements were presented in a wide latitudinal range from the equator to the poles during the main phases of the storm. (6) The ionospheric electric field disturbances associated with IMF-B z fluctuations probably played a very important role in triggering ionospheric irregularities during the relatively weak geomagnetic activity on 7 September, which implies that ionospheric irregularities do not necessarily occur under the severe geomagnetic conditions only.Key Points:• Long-duration depletion of topside TEC recovery was observed during the morning and evening local times in this event • Enhancements of ionospheric irregularities were presented at night with wide latitudinal range during the two main phases of the storm • Ionospheric electric field disturbances due to B z fluctuations probably triggered topside ionospheric irregularities before the main phases

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Storm‐Enhanced Development of Postsunset Equatorial Plasma Bubbles Around the Meridian 120°E/60°W on 7–8 September 2017

Cited by 71 publications

References 41 publications

Coordinated Ground‐Based and Space‐Based Observations of Equatorial Plasma Bubbles

Coordinated Ground‐Based and Space‐Based Observations of Equatorial Plasma Bubbles

Merging of Storm Time Midlatitude Traveling Ionospheric Disturbances and Equatorial Plasma Bubbles

Topside Ionospheric Conditions During the 7–8 September 2017 Geomagnetic Storm

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