Occurrence of blanketing E&amp;lt;sub&amp;gt;s&amp;lt;/sub&amp;gt; layer (E&amp;lt;sub&amp;gt;sb&amp;lt;/sub&amp;gt;) over the equatorial region during the peculiar minimum of solar cycle 24

Yadav, Virendra; Kakad, Bharati; Nayak, Chinmaya; Surve, Ganpat; Emperumel, K.

doi:10.5194/angeo-32-553-2014

Cited by 10 publications

(20 citation statements)

References 48 publications

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“…Tsunoda (2008) analyzed the Es b layers in equatorial regions and suggested that these layers are anti-correlated with the EEJ intensity. Recently, Yadav et al (2014) Therefore, due to the similar characteristics between our example and those reported by other authors, mainly Devasia et al (2006), we infer that the abnormal enhancement of the equatorial sporadic E layer density (indicated by the fbEs peak) and appearance of the Es c layer are related to the CEJ event. Moreover, the radio wave absorption (below 5-8 MHz) occurred in the D region that happened some minutes before the abnormal enhancement of the E layer density is attributed to the additional X-ray ionization due to solar flare events.…”

Section: Methodssupporting

confidence: 90%

Occurrence of the blanketing sporadic E layer during the recovery phase of the October 2003 superstorm

et al. 2016

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We have routinely monitored the total frequency (ftEs) and the blanketing frequency (fbEs) of sporadic E layers with the digital sounder under the magnetic equator in the Brazilian sector. Sporadic layers appear in the equatorial region (Es q ) at heights between 90 and 130 km, mainly due to irregularities in the equatorial electrojet current. However, during the recovery phase of the October 2003 superstorm, an anomalous intensification of the ionospheric density that exceeded the normal ambient background values for local time and location was observed. The parameter fbEs rose to almost 7.5 MHz during this event, due to a type "c" blanketing sporadic layer (Es c ), which is driven by wind shear. This result is discussed in terms of the atmosphere dynamics based on magnetic signature of the equatorial electrojet current using magnetometer data. Also, using data measured by sensors onboard the Geostationary Operational Environmental Satellite (GOES) 10 we analyze the possible influence of the solar flare-associated X-ray flux as an additional source of ionization.

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Section: Methodssupporting

confidence: 90%

Occurrence of the blanketing sporadic E layer during the recovery phase of the October 2003 superstorm

et al. 2016

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“…However, this theory needs to be investigated with more details, in order to establish the connection between E p and Es b occurrence. Recently, Yadav et al (2014) studied the Es b layer occurrence in equatorial regions in the Indian sector for the years 2007 and 2009, and they also concluded that the Es b layers are linked with the CEJ events. In the Brazilian sector, the geomagnetic field configuration has a peculiar behavior in such a way that the magnetic inclination, at a fixed location over the northeast coast, varies at a rate of 20′ per year, corresponding to an apparent northwestward movement of the magnetic equator (Batista et al 2011).…”

Section: Introductionmentioning

confidence: 99%

Competition between winds and electric fields in the formation of blanketing sporadic E layers at equatorial regions

Resende

Batista

Denardini

et al. 2016

Earth Planets Space

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In the present work, we analyze the competition between tidal winds and electric fields in the formation of blanketing sporadic E layers (Es b ) over São Luís, Brazil (2° 31′ S, 44° 16′ W), a quasi-equatorial station. To investigate this competition, we have used an ionospheric E region model (MIRE) that is able to model the Es b layers taking into account the E region winds and electric fields. The model calculates the densities for the main molecular and metallic ions by solving the continuity and momentum equations for each of the species. Thus, the main purpose of this analysis is to verify the electric fields role in the occurrence or disruption of Es b layers through simulations. The first results of the simulations show that the Es b layer is usually present when only the tidal winds were considered. In addition, when the zonal component of the electric field is introduced in the simulation, the Es b layers do not show significant changes. However, the simulations show the disruption of the Es b layers when the vertical electric field is included. In this study, we present two specific cases in which Es b layers appear during some hours over São Luís. We can see that these layers appear when the vertical electric field was weak, which means that the tidal components were more effective during these hours. Therefore, the vertical component of the electric field is the main agent responsible for the Es b layer disruption. which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.

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“…E s / E s b is also observed at equatorial/low‐latitude stations, and their important feature is its peak occurrence during the local summer [ Chandra and Rastogi , ; Devasia , ; Devasia et al , ]. Recently, Yadav et al [] used ionosonde observations from dip equatorial station Tirunelveli in Indian longitude and have shown that E s b is more likely to occur during 13:00–18:00 IST with a peak occurrence at around 16:00 IST during the summer solstice. The occurrence of daytime scintillations during postnoon period and their close association with E s b is in general agreement with earlier studies [ Basu et al , ; Rastogi and Mullen , ].…”

Section: Resultsmentioning

confidence: 99%

Study of equatorial E region irregularities using rare daytime VHF scintillation observations

Yadav¹,

Kakad²,

Pant

et al. 2015

JGR Space Physics

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Scintillations on VHF radio signal are sparsely observed during daytime due to unavailability of strong electron density irregularities in equatorial E or F region. Type I/II irregularities observed at E region altitudes during the daytime are linked with either two‐stream or gradient drift instability. The occurrence of these irregularities in presence of strong blanketing Es (Esb) can produce weak‐moderate scintillations on VHF signal during daytime. Such sparse daytime VHF scintillations are used in the present study to retrieve information about E region irregularities, which are generally examined with radar observations. We use spaced receiver scintillation observations on 251 MHz signal transmitted from geostationary satellite UFO2 (71.2°E) and recorded at Tirunelveli (8.5°N, 77.8°E, dip latitude 0.6°N). Ionosonde data from Trivandrum (8.5°N, 76.6°E, dip latitude 0.5°N) during 2003–2005 is used to confirm the association of daytime scintillations with Esb. The daytime scintillations last for 15–45 min during postnoon hours. Their occurrence closely matches the peak occurrence time of Esb. For the first time, spatial scale lengths of E region irregularities are obtained using the technique introduced by Bhattacharyya et al. (2003). The observed spatial scales are validated using theoretical model. The theoretical model manifests 6–19% density fluctuations in the E region to produce weak scintillations (0.15 ≤S4≤ 0.4) on 251 MHz. The study reveals that scale lengths of E region irregularities are smaller on counter equatorial electrojet (CEEJ) days than non‐CEEJ days, which could be resulting from lower electron temperatures in E region on CEEJ days.

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Occurrence of blanketing E<sub>s</sub> layer (E<sub>sb</sub>) over the equatorial region during the peculiar minimum of solar cycle 24

Cited by 10 publications

References 48 publications

Occurrence of the blanketing sporadic E layer during the recovery phase of the October 2003 superstorm

Occurrence of the blanketing sporadic E layer during the recovery phase of the October 2003 superstorm

Competition between winds and electric fields in the formation of blanketing sporadic E layers at equatorial regions

Study of equatorial E region irregularities using rare daytime VHF scintillation observations

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