Extreme changes in the equatorial electrojet under the influence of interplanetary electric field and the associated modification in the low‐latitude <i>F</i> region plasma distribution

Simi, K. G.; Thampi, Smitha V.; Chakrabarty, D.; Pathan, B. M.; Nayar, S. R. Prabhakaran; Pant, Tarun Kumar

doi:10.1029/2011ja017328

Cited by 22 publications

(23 citation statements)

References 59 publications

(83 reference statements)

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“…Therefore, over the dip equator, a reduction in the zonal electric field and hence the counter electrojet (CEJ) is anticipated. Further, it should be noted that the equatorial CEJ is connected with the R2 FACs via the auroral ionosphere [ Kikuchi et al ., ; Simi et al ., ]. Thus, the overshielding field would produce an increased westward current.…”

Section: Resultsmentioning

confidence: 99%

Unusual depletion of OI 630.0 nm dayglow and simultaneous mesopause heating during the penetration of interplanetary electric field over dip equator

et al. 2015

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Evidence for simultaneous changes in the thermosphere and mesopause associated with penetration electric fields using the OI 630.0 nm and OH (8, 3) dayglow measurements are presented. An unusual decrease in the thermospheric OI 630.0 nm dayglow and an intense heating (~30 K) at OH emission altitudes over a magnetic dip equatorial station, Trivandrum, India, were observed on 9 April 2006, coincident with the penetration of a noontime westward interplanetary electric field. The Sounding of the Atmosphere using Broadband Emission Radiometry observations on board TIMED satellite also revealed heating at the mesopause heights during this period. In addition, ionosonde and magnetometer observations indicated the presence of strong penetration electric fields. We propose that strong heating at the mesopause resulted in the intrusion of additional neutrals, like N 2 , into the emission altitudes and quenched the O( 1 D) atoms therein. The reduced Cowling conductivity at the E region inferred using magnetometer observations further corroborates this proposed mechanism.

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Section: Resultsmentioning

confidence: 99%

Unusual depletion of OI 630.0 nm dayglow and simultaneous mesopause heating during the penetration of interplanetary electric field over dip equator

et al. 2015

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“…As reported by various case studies [e.g., Mannucci et al, 2005;Simi et al, 2012;Tsuji et al, 2012], statistical analyses [e.g., Balan and Rao, 1990], and modeling investigations [e.g., Fuller-Rowell et al, 1994;Lin et al, 2005;Vijaya Lekshmi et al, 2008;Lu et al, 2008], the nature of ionospheric storms depends on disturbance electric (E) fields, local time (LT), season, and geophysical parameters. On a global scale, storm time magnetospheric processes change the ionosphere's regular quiet time electrodynamics, neutral wind circulation, and chemical makeup.…”

Section: Introductionmentioning

confidence: 99%

Perturbation electric fields and disturbance currents investigated during the 25 September 1998 great storm

Horvath

Lovell

2014

JGR Space Physics

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This study investigates the ionosphere's response to the 25 September 1998 great storm and utilizes multi‐instrument observations covering the Australian (140°E; geographic) and Indian (75°E) longitude sectors. Results show the domination of eastward (westward) electrojet at 140°E (75°E). Its causative net eastward (westward) perturbation electric (E) field drove the forward (reverse) plasma fountain, caused the presence (absence) of the equatorial ionization anomaly (EIA). These strong longitudinal differences were due to a combination of various LT‐dependent, E field‐driven, and competing mechanisms. Perturbation E fields are identified as prompt penetration E field (PPEF) and disturbance dynamo E field (DDEF). Due to the later (earlier) local time at 140°E (75°E), the undershielding PPEF was eastward (westward) directed early in the main phase. A series of periodic substorms occurred during the recovery phase. The substorm‐related eastward PPEFs became overpowered by westward DDEFs over India but remained dominant in the Australian sector. Thus, eastward PPEFs (westward DDEFs) dominated at 140°E (75°E). At 140°E these eastward PPEFs exhibited a strong positive correlation with the variations of both the cross polar cap potential drop and the asymmetric ring current, significantly increased the net equatorial upward E × B drift and thus caused EIA development with plasma bubbles scintillating GPS signals. Based on the strong and independent correlation of these asymmetric ring current events with both the EIA development and the scintillation activity, we propose that the ASY‐H index could provide a natural tool for modeling EIA development and scintillation episodes during severe storms characterized by periodic substorm‐related eastward PPEFs.

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“…Huang et al [] observed nearly symmetric four‐cell convection for B z / B y ≈7, with two normal cells in lower latitudes and two reversed cells in polar cap. Rastogi and Patel [] reported reversal of electric field during northward IMF turning at the equator using EEJ data, and after that several examples were presented by many researchers [ Patel , ; Fejer et al , ; Kelley et al ; Huang et al , ; Wei et al , ; Simi et al , ]. It was thought that westward electric field observed at the equator is dusk‐to‐dawn IEF, penetrated during northward Bz.…”

Section: Introductionmentioning

confidence: 99%

Characteristics of penetration electric fields to the equatorial ionosphere during southward and northward IMF turnings

Bhaskar

Vichare

2013

JGR Space Physics

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[1] The signatures of abrupt turnings of the vertical component of the interplanetary magnetic field (IMF), Bz, can be seen at equatorial latitudes through the prompt transmission of high-latitude electric fields to the lower latitudes, called as prompt penetration electric field (PPE). The present work studies the signatures of PPE in daytime equatorial electrojet (EEJ) index derived in the Indian sector during [2001][2002][2003][2004][2005]. The signatures are observed in polar (PCN index) and equatorial (EEJ index) ionosphere almost instantaneously (< 1 min). The communication time of 12˙6 min is observed between bow shock nose and the equatorial ionosphere, and it is found to have inverse relationship with radial component of solar wind velocity during southward and northward Bz turnings which might indicate magnetosphere crossing time scale by solar wind. Ionospheric reconfiguration time during southward turnings shows inverse relationship with solar wind flow in contrast to northward turnings with "no relationship," indicating differences in underlying physical mechanisms during both turnings. We observe no local time dependence (within 06-18 h) in conductivity-corrected EEJ signatures associated with Bz turnings. Regression analysis between conductivity-corrected EEJ and interplanetary electric field shows higher efficiency during northward turnings. However, further analysis investigating the effect of actual orientation of Bz indicates that the magnitude of northward Bz does not have influence on the ionospheric signatures. It is noticed that the response signatures are mainly controlled by the magnitudes of southward Bz. Thus, the present study signifies the role of inner magnetospheric shielding electric field in addition to ceasing of convection during northward turnings.Citation: Bhaskar, A., and G. Vichare (2013), Characteristics of penetration electric fields to the equatorial ionosphere during southward and northward IMF turnings,

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Extreme changes in the equatorial electrojet under the influence of interplanetary electric field and the associated modification in the low‐latitude F region plasma distribution

Cited by 22 publications

References 59 publications

Unusual depletion of OI 630.0 nm dayglow and simultaneous mesopause heating during the penetration of interplanetary electric field over dip equator

Unusual depletion of OI 630.0 nm dayglow and simultaneous mesopause heating during the penetration of interplanetary electric field over dip equator

Perturbation electric fields and disturbance currents investigated during the 25 September 1998 great storm

Characteristics of penetration electric fields to the equatorial ionosphere during southward and northward IMF turnings

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