Formation of sporadic E (Es) layer by homogeneous and inhomogeneous horizontal winds

Dalakishvili, Giorgi; Didebulidze, G. G.; Todua, Maya

doi:10.1016/j.jastp.2020.105403

Cited by 8 publications

(36 citation statements)

References 44 publications

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“…In the present study the suggested theoretical mechanism of the Es layer formation takes into account an arbitrary wind height profile. This approach is different from earlier considerations [10,24]. In this study the recently obtained results of the case of horizontal wind are also generalized.…”

Section: Of 25mentioning

confidence: 82%

“…In the recent studies [10,24] have shown that, in adition to earlier considerations [2,3,15,27,28], taking into account the "windshear" effect, the wind magnitude and direction were important for development of ion/electron convergence (or divergence/deplition) in certain height regions. It was also shown that Es layer density is also controlled by ion ambipolar diffusion.…”

Section: Of 25mentioning

confidence: 87%

“…Es layers mainly occur during nighttime in the lower thermosphere, at altitudes between 90-150km. This fact indicates that in this range of altitudes is provided conditions for ion/electron convergence into narrow layer in this region [6][7][8][9][10][11][12]. This convergence and consequently the formation of the Es layer can be caused by horizontal wind with vertical shear (windshear theory) [6,7,[13][14][15][16][17][18], by electric field and its variations [19,20] or/and by the combined action of all these effects [21][22][23].…”

Section: Introductionmentioning

confidence: 89%

“…or depletion occur [10,12,24] The loss rate of molecular ions (e.g., NO+ and O2+) increases during ion/electron convergence into thin dense layer, which in turn causes the dominance of long-lived heavy metallic ions (e.g., Fe+ and Mg+), which is a phenomenon that has been observed in nighttime Es layers [25,26].…”

Section: Of 25mentioning

confidence: 99%

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The Role of Neutral Wind Velocity and Its Vertical Component on Predictability of Formation and Localization of Sporadic E(Es)

Didebulidze¹,

Dalakishvili²,

Todua³

et al. 2023

Preprint

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The formation and localization of sporadic E(Es) layers predicted by the ions vertical drift velocity and its vertical change in the lower thermosphere during nighttime are shown analytically and by numerical simulations. The consideration of existence of a minimum negative value of the vertical change of the ions vertical drift velocity as a necessary condition of formation of Es layer and determining ions convergence rate into this layer, is extended in case of the presence of vertical wind. Upward vertical wind can shift the convergence regions upward, while downward vertical wind shift them downward, unlike the cases of presence of only meridional and zonal winds. It also changes the ion convergence rate compared to the one with just a horizontal wind. It is shown for the first time that the upward constant wind also causes the convergence of ions with maximum rate in the region where the ion-neutral collision frequency is equal to their cyclotron frequency. While demonstrating the presented theory by numerical simulations, HWM14 data is used for the meridional and zonal wind velocity profiles and the presence of its vertical component is assumed. In this case, in addition to the estimated ion drift velocity and its vertical changes, their initial distribution and ambipolar diffusion also determine the development of ion convergence/divergence processes. For small magnitude of vertical wind velocity, its significant influence on the ions/electrons behavior is demonstrated, which shows the importance of both tidal wind and wind changes caused by the propagation of atmospheric gravity waves on the formation of the Es layer. In this theoretical research it is shown that the realistic profile of the wind velocity, which takes into account the vertical component along with its zonal and meridional ones, is important for prediction of the Es layers formation, as well as regions of ion depletion.

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Section: Of 25mentioning

confidence: 82%

Section: Of 25mentioning

confidence: 87%

Section: Introductionmentioning

confidence: 89%

Section: Of 25mentioning

confidence: 99%

See 2 more Smart Citations

The Role of Neutral Wind Velocity and Its Vertical Component on Predictability of Formation and Localization of Sporadic E(Es)

Didebulidze¹,

Dalakishvili²,

Todua³

et al. 2023

Preprint

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“…The wind shear theory suggests that the Es layer is formed at the convergence wind shear nodes (Dalakishvili et al., 2020; Haldoupis, 2011; Whitehead, 1960). However, the height difference between the Es layer and the convergence wind shear nodes exists from both observations and simulations.…”

Section: Discussionmentioning

confidence: 99%

Altitudinal and Latitudinal Variations in Ionospheric Sporadic‐E Layer Obtained From FORMOSAT‐3/COSMIC Radio Occultation

Qiu

Yan

et al. 2021

JGR Space Physics

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Sporadic E (Es) layers are known for their layered structures with enhanced electron density. Recently, some scientists have studied the relationship between the occurrence rate and intensity of the Es layer in the global distribution. However, the relationship between the Es layer parameters (Es layer occurrence rate, Es layer intensity, Es layer thickness) in the vertical direction seems to be ignored to date. This paper highlights the vertical profiles of the occurrence rate, intensity, and thickness of the Es layers by using scintillation index (S4) from FORMOSAT‐3/COSMIC satellites from July 2007 to March 2015. The results show that there are some persistent differences between the occurrence rate, intensity, and thickness of the Es layers in the vertical profiles, which is different from their general similarity in the latitude distribution. It is found that the Es layer occurrence rate has a maximum value at ∼102 km altitude, but the Es layer intensity and Es layer thickness reach their maximum at an altitude of ∼110 km. Besides, the intensity and thickness of the Es layer exhibit a high linear relationship, which suggests that the larger electron density of the Es layer, the thicker its thickness. The Horizontal Wind Model (HWM14) indicates that the latitudinal variations in Es layers parameters are highly coincident with the zonal wind shear. However, the altitudinal variations in Es layers parameters do not agree well with the zonal wind shear.

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Correlation betweenfoEsand zonal winds over Rome, Okinawa and Townsville using Horizontal Wind Model (HWM14) during solar cycle 22

Gul

Ameen

Verhulst

2021

Advances in Space Research

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Formation of sporadic E (Es) layer by homogeneous and inhomogeneous horizontal winds

Cited by 8 publications

References 44 publications

The Role of Neutral Wind Velocity and Its Vertical Component on Predictability of Formation and Localization of Sporadic E(Es)

The Role of Neutral Wind Velocity and Its Vertical Component on Predictability of Formation and Localization of Sporadic E(Es)

Altitudinal and Latitudinal Variations in Ionospheric Sporadic‐E Layer Obtained From FORMOSAT‐3/COSMIC Radio Occultation

Correlation betweenfoEsand zonal winds over Rome, Okinawa and Townsville using Horizontal Wind Model (HWM14) during solar cycle 22

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