Characteristics of equatorial plasma bubbles observed by TEC map based on ground-based GNSS receivers over South America

Barros, Diego; Takahashi, H.; Wrasse, C. M.; Figueiredo, C. A. O. B.

doi:10.5194/angeo-36-91-2018

Cited by 53 publications

(90 citation statements)

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“…The EPBs occurring around the Eastern Pacific, South America, and Atlantic regions (−120–0°E) can rise to over 700 km. This is consistent with the global distribution of density irregularities in the topside ionosphere (600 km) seen in ROCSAT‐1 ion density observations (Su et al, 2006) and TEC observations (Barros et al, 2018). However, some equinoctial EPBs occurring around 60°E to 120°W only grow up to about 500 km.…”

Section: Observations and Discussionsupporting

confidence: 88%

“…However, the EPBs that occur around 60°E to 120°W can only extend up to about ±25° magnetic latitudes in equinoxes. Barros et al (2018) suggested that the EPBs can extend to higher latitude in the South American region in December solstice depending on the apex height of EPBs and the strength of the PRE. It is reasonable since that the PRE can transport the plasma to higher altitude and latitude, then the altitudinal and latitudinal extent of EPBs would be higher.…”

Section: Observations and Discussionmentioning

confidence: 99%

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Climatology of the Equatorial Plasma Bubbles Captured by FORMOSAT‐3/COSMIC

Chou

Pedatella

et al. 2020

JGR Space Physics

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The FORMOSAT-3/COSMIC (F3/C) satellites are used to study the climatology of equatorial plasma bubbles (EPBs) during the low to moderate solar flux years (2008)(2009)(2010)(2011)(2012)(2013). We use the F3/C total electron content to identify the presence of EPBs and investigate the background conditions for the initiation of EPBs. The results reveal that the EPB activities have strong solar dependence. The longitudinal and seasonal trends of EPBs are highly correlated to the angle between the dusk solar terminator and magnetic field lines near the magnetic equator. Asymmetries of EPBs between solstices and equinoxes exist and could be due partly to the asymmetry of equatorial ionization anomaly structures, which result in longitudinal differences as well. EPBs extend to higher altitudes and latitudes during the ascending phase of Solar Cycle 24 (2011-2013) due mainly to the increase of background electron density. However, an altitudinal asymmetry of EPBs occurs in moderate solar flux years, which is likely due to the suppression or lower growth and occurrence rates of EPBs. In addition to vertical drift, tidal forcing also contributes to the longitudinal and seasonal distributions of EPBs. Upwellings and precursor waves preceding the EPBs are observed climatologically, which likely play a vital role in initiating the EPBs. This study also reveals a vertical connection between the equatorial ionospheric irregularities and atmospheric forcing on a climatological basis.Plain Language Summary Equatorial plasma bubbles (EPBs) are an important space weather phenomenon that are often generated over the magnetic equator around twilight. They are ionospheric irregularities that can cause plasma depletions along the geomagnetic field lines, displaying geomagnetic conjugacy in both hemispheres. Since the ionospheric plasma is one of the significant error sources of the Global Navigation Satellite System (GNSS), EPBs are considered to be a primary disrupter of GNSS communication and navigation. Postsunset rise (PSSR) of the equatorial ionosphere due to vertical ion drift is often used to explain the occurrence of EPBs; however, it cannot fully explain the day-to-day variability of EPBs and the features of EPBs in patches and clusters. Mysteries abound around the EPBs and the underlying physics that initiates the EPBs remain unsolved. Here we utilize the FORMOSAT-3/COSMIC to investigate the underlying background conditions for the generation of EPBs. We find that, in addition to PSSR, symmetric equatorial ionization anomaly, as well as tidal forcing, appears to provide conditions favorable for the initiation of EPBs. Atmospheric tidal waves contribute to the longitudinal and seasonal distribution of EPBs as well. Bottomside ionospheric undulations due to atmospheric forcing are likely playing a vital role in initiating the EPBs.

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Section: Observations and Discussionsupporting

confidence: 88%

Section: Observations and Discussionmentioning

confidence: 99%

Climatology of the Equatorial Plasma Bubbles Captured by FORMOSAT‐3/COSMIC

Chou

Pedatella

et al. 2020

JGR Space Physics

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“…When this occurs, it is called the critical level and, as a result, the gravity waves cannot propagate upward (Vadas, 2007). Barros et al (2018), Figueiredo, Buriti, et al (2017), and Makela et al (2013) reported that the nighttime thermospheric neutral wind magnitude, observed by Fabry-Perot interferometer in the Brazilian northeast, is not greater than 150 m/s. Moreover, Drob et al (2015) updated the Horizontal Wind Model and verified that the diurnal thermospheric neutral wind does not exceed 160 m/s on quiet days.…”

Section: Propagation Directionmentioning

confidence: 99%

Medium‐Scale Traveling Ionospheric Disturbances Observed by Detrended Total Electron Content Maps Over Brazil

et al. 2018

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A ground‐based network of Global Navigation Satellite Systems receivers has been used to monitor medium‐scale traveling ionospheric disturbances (MSTIDs). MSTIDs were studied using total electron content perturbation maps and keograms over south‐southeast of Brazil during the period from December 2012 to February 2016. In total, 826 MSTIDs were observed mainly in daytime, thus presenting median values of horizontal wavelength, period, and horizontal phase velocity of 452 ± 107 km, 24 ± 4 min. and 323 ± 81 m/s, respectively. The direction of propagation varies on the season: during the winter (June–August), the waves preferentially propagated to north‐northeast, while in the other seasons the waves propagated to other directions. The anisotropy observed in the MSTID propagation direction could be associated with the region of the gravity wave generation that takes place in the troposphere. We also found that the MSTIDs were observed most frequently during the daytime, between 11 and 15 local time in winter and near to dusk solar terminator (17–19 local time) in the other seasons. Furthermore, the occurrence of MSTIDs was higher in winter. We suggest that atmospheric gravity waves in the thermosphere, mesosphere, and troposphere could play an important role in generating the MSTIDs and the propagation direction may depend on location of the wave sources.

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“…During quiet times, the prereversal enhancement (PRE) of the zonal electric field is responsible for the enhanced upward E × B drift after sunset, which elevates the ionospheric height and subsequently amplifies the growth rate of R-T The morphological features and spatial/temporal variability of EPBs have been widely investigated via case studies and statistical analysis using different observational methods. Moreover, with the fast-growing and global availability of ground-based Global Navigation Satellite Systems (GNSS) measurements and space-based radio occultation data, the evolution characteristics of EPBs can be monitored continuously on both global or regional scales (Aa et al, 2018;Barros et al, 2018;Buhari et al, 2014Buhari et al, , 2017Cherniak et al, 2014;Katamzi-Joseph et al, 2017;Ma & Maruyama, 2006;Nishioka et al, 2008;Takahashi et al, 2015). The spatial variation of EPBs can be derived from the dark streaks of emission depletion in optical observations from ground-based all-sky imagers (ASIs) or space-based ultraviolet (UV) imaging spectrographs (Comberiate & Paxton, 2010;Hickey et al, 2018;Kelley et al, 2003;Kil et al, 2009;Makela, 2006;Martinis et al, 2015;Otsuka et al, 2002;Shiokawa et al, 2015).…”

Section: Introductionmentioning

confidence: 99%

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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Characteristics of equatorial plasma bubbles observed by TEC map based on ground-based GNSS receivers over South America

Cited by 53 publications

References 50 publications

Climatology of the Equatorial Plasma Bubbles Captured by FORMOSAT‐3/COSMIC

Climatology of the Equatorial Plasma Bubbles Captured by FORMOSAT‐3/COSMIC

Medium‐Scale Traveling Ionospheric Disturbances Observed by Detrended Total Electron Content Maps Over Brazil

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

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