On the nature of low‐latitude <i>E</i><sub>s</sub> influencing the genesis of equatorial plasma bubble

Joshi, L. M.; Patra, Amit; Pant, Tarun Kumar; Rao, Sandhya

doi:10.1029/2012ja018122

Cited by 13 publications

(25 citation statements)

References 22 publications

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“…On the other hand, a very recent paper by Joshi et al . [] highlighted the role of the E sporadic ( E s) in the genesis of equatorial plasma bubbles also during nighttime. Our results indicate that the daytime amplitude scintillations are concentrated in the interval 09:00–14:00 UT (05:00–10:00 LT) (Figure ), when E s layers are often observed by the AIS‐INGV ionosonde.…”

Section: Summary and Discussionsupporting

confidence: 86%

Comparative analysis of spread‐F signature and GPS scintillation occurrences at Tucumán, Argentina

et al. 2013

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We analyze data recorded from October 2010 to September 2011, during the ascending phase of the 24th solar cycle, from an Advanced Ionospheric Sounder‐Istituto Nazionale di Geofisica e Vulcanologia ionosonde and a GPS Ionospheric Scintillation and total electron content (TEC) monitor scintillation receiver, colocated at low latitude in the Southern American longitudinal sector (Tucumán, 26.9°S, 294.6°E, magnetic latitude 15.5°S, Argentina). The site offers the opportunity to perform spread‐F and GPS scintillation statistics of occurrence under the southern crest of the equatorial ionospheric anomaly. Spread‐F signatures, classified into four types (strong range spread‐F (SSF), range spread‐F, frequency spread‐F (FSF), and mixed spread‐F), the phase and amplitude scintillation index (σΦ and S4, respectively), the TEC, and the rate of TEC parameter, marker of the TEC gradients, that can cause scintillations, are considered. The seasonal behavior results as follows: the occurrence of all four types of spread‐F is higher in summer and lower in winter, while the occurrence of scintillations peaks at equinoxes in the postsunset sector and shows a minimum in winter. The correspondence between SSF and scintillations seems to be systematic, and a possible correlation between S4 and FSF peaks is envisaged at the terminator. The investigation focused also on two particular periods, from 12 to 16 March 2011 and from 23 to 29 September 2011, both characterized by the simultaneous presence of SSF signatures and scintillation phenomena, allowing to discuss the role of traveling ionospheric disturbances as a strong candidate causing ionospheric irregularities.

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Section: Summary and Discussionsupporting

confidence: 86%

Comparative analysis of spread‐F signature and GPS scintillation occurrences at Tucumán, Argentina

et al. 2013

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“…Recently, Joshi et al . [, ] have reported that the presence of the blanketing‐type E s in the low latitudes can suppress the genesis of the EPBs and plays an important role in explaining the day‐to‐day variability of the ESF. Also, the low‐latitude E region conductivity has been known to influence the evening electrodynamics related with the prereversal enhancement (PRE).…”

Section: Resultsmentioning

confidence: 99%

“…It must be mentioned here that 19:30 IST to 20:30 IST is usually the time of the F layer attaining the peak height due to the PRE and also the time of the genesis of the EPB. Possibly, the occurrence of the Es b over Sriharikota during that period in category 2 cases resulted in the suppression of the EPB genesis over Sriharikota longitude by short circuiting the polarization electric field [ Stephan et al ., ; Joshi et al ., , ]. Spatial observation of low‐latitude E s could not be made with the current observational setup used for the investigation.…”

Section: Resultsmentioning

confidence: 99%

LSWS linked with the low‐latitude E_s and its implications for the growth of the R‐T instability

Joshi

2016

JGR Space Physics

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A comprehensive investigation of spread F irregularities over the Indian sector has been carried out using VHF radar and ionosonde observations. Two different categories of spread F observations, one where the onset of the range spread F (RSF) was concurrent with the peak h′F (category 1) and another where the RSF onset happened ~90 min after the peak h′F time (category 2), are presented. RSF in category 2 was preceded by the presence of oblique echoes in ionograms, indicating the irregularity genesis westward of Sriharikota. The average peak h′F in category 1 was ~30 km higher than that in category 2 indicating the presence of standing large‐scale wave structure (LSWS). Occurrence of the blanketing Es during 19:30 to 20:30 Indian Standard Time in category 1 (category 2) was 0% (>50%). Model computation is also carried out to further substantiate the observational results. Model computation indicates that zonal variation of low‐latitude Es can generate zonal modulation in the F layer height rise. It is found that the modulation of the F layer height, linked with the low‐latitude Es, assists the equatorial spread F onset by modifying both the growth rate of the collisional Rayleigh‐Taylor (R‐T) instability and also its efficiency. A predominant presence of low‐latitude Es has been observed, but the increase in the F layer height and the R‐T instability growth in the evening hours will maximize with complete absence of low‐latitude Es. A new mechanism for the generation of LSWS and its implications on R‐T instability is discussed.

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“…Also, no E s layer disruption occurs when PRE amplitude decreases or is inhibited under DDEFs. Recently Joshi, Patra, Pant, and Rao () have investigated the possible connection between low‐latitude E s layers and EPBs during geomagnetically quiet days over Indian sector. Their results also indicate that when blanketing type E s occurs at low latitudes for long duration in the sunset hours, significant rise in PRE height is not observed resulting in absence of EPBs.…”

Section: Discussionmentioning

confidence: 99%

“…They suggested that the E and F region coupling around sunset could affect strongly the linkage between PRE drifts and E s layer disruption or formation. Using Sriharikota ionosonde, Joshi, Patra, and Rao () and Joshi, Patra, Pant, and Rao () have examined the role of quiet time low‐latitude E s layer activity on the generation of ESF irregularities around the sunset terminator over India. They suggested that E s layers play significant role in the occurrence of ESF irregularities in the sunset terminator depending upon the type of E s layer.…”

Section: Introductionmentioning

confidence: 99%

The Role of Storm Time Electrodynamics in Suppressing the Equatorial Plasma Bubble Development in the Recovery Phase of a Geomagnetic Storm

et al. 2018

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We investigate the role of storm time electrodynamics in suppressing the equatorial plasma bubble (EPB) development using multi‐instruments over India during a moderate geomagnetic storm that occurred on 2 October 2013 where Dst minimum reached ~−80 nT. This storm produced unique signatures in the equatorial ionosphere such that equatorial electrojet strength showed signatures of an abrupt increase of its strength to 150 nT and occurrence of episodes of counter electrojet events. During the main phase of the storm, the interplanetary magnetic field Bz is well correlated with the variations in the equatorial electrojet/counter electrojet suggesting the role of undershielding/overshielding electric fields of magnetospheric origin. Further, observations showed the presence of strong F3 layers at multiple times at multiple stations due to undershielding electric field. Interestingly, we observed simultaneous presence of F3 layers and suppression of EPBs in the dusk sector during the recovery phase. While strong EPBs were observed before and after the day of the geomagnetic storm, suppression of the EPBs on the storm day during “spread F season” is intriguing. Our further analysis using low‐latitude station, Hyderabad, during the time of prereversal enhancement suggests that intense Esb layers were observed on the storm day but were absent/weak on quiet days. Based on these results, we suggest that the altitude/latitude variation of disturbance dynamo electric fields/disturbance winds may be responsible for simultaneous detection of F3 layers, occurrence of low‐latitude Es layers, and suppression of EPBs during the storm day along the sunset terminator.

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On the nature of low‐latitude E_s influencing the genesis of equatorial plasma bubble

Cited by 13 publications

References 22 publications

Comparative analysis of spread‐F signature and GPS scintillation occurrences at Tucumán, Argentina

Comparative analysis of spread‐F signature and GPS scintillation occurrences at Tucumán, Argentina

LSWS linked with the low‐latitude E_s and its implications for the growth of the R‐T instability

The Role of Storm Time Electrodynamics in Suppressing the Equatorial Plasma Bubble Development in the Recovery Phase of a Geomagnetic Storm

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On the nature of low‐latitude Es influencing the genesis of equatorial plasma bubble

Cited by 13 publications

References 22 publications

Comparative analysis of spread‐F signature and GPS scintillation occurrences at Tucumán, Argentina

Comparative analysis of spread‐F signature and GPS scintillation occurrences at Tucumán, Argentina

LSWS linked with the low‐latitude Es and its implications for the growth of the R‐T instability

The Role of Storm Time Electrodynamics in Suppressing the Equatorial Plasma Bubble Development in the Recovery Phase of a Geomagnetic Storm

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On the nature of low‐latitude E_s influencing the genesis of equatorial plasma bubble

LSWS linked with the low‐latitude E_s and its implications for the growth of the R‐T instability