A study of blanketing sporadic E in the equatorial region

Oyinloye, J.O

doi:10.1016/0032-0633(71)90109-7

Cited by 16 publications

(22 citation statements)

References 15 publications

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“…Therefore, scintillation is associated with E sb , which is in accordance with the Tsunoda model (Tsunoda 2008). This result is also consistent with that obtained by Oyinloye (1971), which indicated E sb dependence as a function of I in the vicinity of the dip equator. He showed that there is a high occurrence rate for E sb (15 to 27 %), where |I|≈8°.…”

Section: Distribution Of Daytime Ghz Scintillation In the Vicinity Ofsupporting

confidence: 93%

“…In Fig. 5, the two black lines are the approximate latitudes for the equatorward boundaries for E sb (EBE sb ), according to Oyinloye (1971). This is the average boundary, and they presumably are the average locations for the equatorward boundary for the metallic ion streams (MIS) described in Tsunoda (2008).…”

Section: Distribution Of Daytime Ghz Scintillation In the Vicinity Ofmentioning

confidence: 99%

“…He showed that there is a high occurrence rate for E sb (15 to 27 %), where |I|≈8°. For further details Oyinloye model (Oyinloye 1971) on the occurrence of E sb on the different I, the reader is referred to Fig. 1 page 2 of Tsunoda (2008).…”

Section: Distribution Of Daytime Ghz Scintillation In the Vicinity Ofmentioning

confidence: 99%

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Daytime gigahertz scintillations near magnetic equator: relationship to blanketing sporadic E and gradient-drift instability

et al. 2015

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Observations made in non-equatorial regions appear to support the hypothesis that the daytime scintillation of radio signals at gigahertz (GHz) frequencies is produced by the gradient-drift instability (GDI) in the presence of a blanketing sporadic E (E sb ) layer. However, the only evidence offered, thus far, to validate this notion, has been some observations of E sb in the vicinity of GHz scintillations. A more comprehensive evaluation requires information about electric field, together with the presence of a steep gradient, which is presumed to be that of E sb . In this regard, the region in the vicinity of the equatorial electrojet (EEJ) appears to be an ideal "laboratory" to conduct such experiments. The dominant driver of electron drift there is the same as that of the EEJ, the vertical polarization electric field, and indications are that the presence of E sb in that vicinity is controlled by a balance in horizontal transport of E sb , between the EEJ electric field and the neutral wind, as described in a model by Tsunoda (On blanketing sporadic E and polarization effects near the equatorial electrojet, 2008). In this paper, we present, for the first time, results from a comprehensive study of daytime GHz scintillations near the magnetic equator. The properties, derived from measurements, are shown, for the first time, to be consistent with a scenario in which E sb presence is dictated by the Tsunoda model, and the plasma-density irregularities responsible for GHz scintillations appear to be produced by the GDI.

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Section: Distribution Of Daytime Ghz Scintillation In the Vicinity Ofsupporting

confidence: 93%

Section: Distribution Of Daytime Ghz Scintillation In the Vicinity Ofmentioning

confidence: 99%

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Daytime gigahertz scintillations near magnetic equator: relationship to blanketing sporadic E and gradient-drift instability

et al. 2015

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“…Nevertheless, there is a report of an equinoctial peak E sb occurrence at American and African sectors during a high solar activity period (Oyinloye, 1971). The past investigations of E sb at low-latitude stations provide two important observational aspects of E sb occurrence: (i) the occurrence decreases as we move from low latitude to equatorial stations where EEJ current is stronger (Oyinloye, 1971;Abdu et al, 1996) and (ii) E sb at equatorial regions is mainly seen during periods of CEEJ or weak EEJ (Bhargava and Subrahmanyan, 1964;Chandra and Rastogi, 1975;Sen Gupta and Krishna Murthy, 1975;Devasia et al, 2006 winter (January-February) and vernal equinox of 2009 as compared to 2007 is an interesting observation. In order to understand this discrepancy, we examine the dependence of E sb occurrence on EEJ and CEEJ.…”

Section: Seasonal Variation Of the E Sb Occurrencementioning

confidence: 99%

“…However, this theory fails at the dip equator where the Earth's magnetic field is nearly horizontal. It is reported that E sb is observed at equatorial latitudes as well but its occurrence is less than that away from the equator (Oyinloye, 1971;Abdu et al, 1996). Reddy and Devasia (1973) proposed theories to explain the formation of E sb at equatorial latitudes, which are based on the horizontal convergence of ions.…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2014

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Abstract.A thin and highly dense sporadic E layer, which can occasionally block the upper ionospheric layers, is called blanketing sporadic E (E sb ). We present the statistical seasonal local time occurrence pattern of E sb at equatorial station Tirunelveli (8.7 • N, 77.8 • E, dip latitude 0.7 • N) during the extended minimum of solar cycle 24 (2007-2009). In spite of nearly the same average solar activity during both 2007 and 2009, considerable differences are noticed in the seasonal occurrence of E sb during this period. The percentage of E sb occurrence is found to be the highest during the summer solstice (≥ 50 %) for both 2007 and 2009, which is in general accordance with the earlier studies. The occurrences of E sb during the vernal equinox (∼ 33 %) and January-February (∼ 28 %) are substantial in 2009 as compared to those during the same seasons in 2007. We find that, during winter (January-February), ∼ 75 % of E sb occurred during or just after the period of sudden stratospheric warming (SSW). We suggest that enhanced E sb occurrence during winter (January-February) and the vernal equinox of 2009 could be associated with SSW-driven changes in the E region ambient conditions. Furthermore, the close association of E sb with counter equatorial electrojet (CEEJ) suggested by earlier studies is re-examined carefully using the scenario of E sb occurrence on non-CEEJ days. Such an exercise is crucial as we are unaware whether the physical mechanisms driving E sb and CEEJ are linked or not. We find that, of all the seasons, the association of E sb and CEEJ is strongest during winter (November-December).

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Quiet and Disturbed Time Characteristics of Blanketing Es (Esb) During Solar Cycle 23

et al. 2017

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A sporadic E layer with dense ionization blocks the upper ionospheric layers in ionosonde observations and it is called, blanketing sporadic E (Esb). Although earlier studies have demonstrated that Esb occurrence is dependent on solar activity, seasons, local time, and equatorial electrojet/counter equatorial electrojet (EEJ/CEEJ) strength, the physics behind this dependence is not well established particularly at the dip equatorial stations. Moreover, fewer comprehensive studies are available on Esb. Present work is a detailed statistical study of Esb occurrence and its characteristics during solar cycle 23 (1996–2006) at Indian dip equatorial station Trivandrum (dip latitude 0.5°N). In present study, solar flux dependence of Esb occurrence is clearly evident not only for magnetically quiet but also for the disturbed periods with maximum during low solar activity. Known seasonal peak Esb occurrence during summer (May–August) is found to be dominated by larger percentage of total blanketing events (fbEs ≥ 8 MHz) on magnetically disturbed days as compared to quiet days. We noticed prevalent Esb occurrence in the postmidnight (00–06 India Standard Time) periods during low solar activity. Besides Esb characteristics, the present study aims to investigate effect of solar flux on association of Esb and CEEJ. Coexistence of Esb and CEEJ is emphasized in earlier observational studies. However, any dependence of their association on solar flux is not yet examined. We find that their association is weaker during low solar activity as compared to high solar activity in summer, indicating that Esb occurrence is highly likely on CEEJ days during high solar activity periods.

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A study of blanketing sporadic E in the equatorial region

Cited by 16 publications

References 15 publications

Daytime gigahertz scintillations near magnetic equator: relationship to blanketing sporadic E and gradient-drift instability

Daytime gigahertz scintillations near magnetic equator: relationship to blanketing sporadic E and gradient-drift instability

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

Quiet and Disturbed Time Characteristics of Blanketing Es (Esb) During Solar Cycle 23

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A study of blanketing sporadic E in the equatorial region

Cited by 16 publications

References 15 publications

Daytime gigahertz scintillations near magnetic equator: relationship to blanketing sporadic E and gradient-drift instability

Daytime gigahertz scintillations near magnetic equator: relationship to blanketing sporadic E and gradient-drift instability

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

Quiet and Disturbed Time Characteristics of Blanketing Es (Esb) During Solar Cycle 23

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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