Sporadic E tidal variabilities and characteristics observed with the Cyprus Digisonde

Oikonomou, Christina; Haralambous, Haris; Haldoupis, C.; Meek, C. E.

doi:10.1016/j.jastp.2014.07.014

Cited by 39 publications

(34 citation statements)

References 47 publications

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“…There remains the question about the role of the QDT in the formation of Es, and a possible connection with the QDT neutral wind shear at mid latitudes. Some publications reported that no QDT signature was found in some ionospheric records (e.g., Cyprus, 35 • N, 33 • E, Oikonomou et al, 2014). However, 6 h tidal signatures were observed in lower ionospheric Es parameters already (Tong et al, 1988;Morton et al, 1993).…”

Section: Jacobi Et Al: Quarterdiurnal Signature In Sporadic Ementioning

confidence: 97%

“…According to the wind shear theory (Whitehead, 1961) the process of Es formation is a metallic ion convergence owing to the interaction between the Earth's magnetic field, the metallic ion concentration, and the vertical gradient of the horizontal neutral wind, "wind shear" in brief. Neglecting diffusion, the vertical velocity component of the neutral gas, and the electric force, the vertical ion drift w I may be written as (e.g., Haldoupis, 2012;Fytterer et al, 2014;Oikonomou et al, 2014) w I = r · cos I 1 + r 2 U +…”

Section: Introductionmentioning

confidence: 99%

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Quarterdiurnal signature in sporadic E occurrence rates and comparison with neutral wind shear

et al. 2019

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Abstract. The GPS radio occultation (RO) technique is used to study sporadic E (Es) layer plasma irregularities of the Earth's ionosphere on a global scale using GPS signal-to-noise ratio (SNR) profiles from the COSMIC/FORMOSAT-3 satellite. The maximum deviation from the mean SNR can be attributed to the height of the Es layer. Es are generally accepted to be produced by ion convergence due to vertical wind shear in the presence of a horizontal component of the Earth's magnetic field, while the wind shear is provided mainly by the solar tides. Here we present analyses of quarterdiurnal tide (QDT) signatures in Es occurrence rates. From a local comparison with mesosphere/lower thermosphere wind shear obtained with a meteor radar at Collm (51.3∘ N, 13.0∘ E), we find that the phases of the QDT in Es agree well with those of negative vertical shear of the zonal wind for all seasons except for summer, when the QDT amplitudes are small. We also compare the global QDT Es signal with numerical model results. The global distribution of the Es occurrence rates qualitatively agrees with the modeled zonal wind shears. The results indicate that zonal wind shear is indeed an important driving mechanism for the QDT seen in Es.

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Section: Jacobi Et Al: Quarterdiurnal Signature In Sporadic Ementioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

Quarterdiurnal signature in sporadic E occurrence rates and comparison with neutral wind shear

et al. 2019

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“…Since the plasma must remain neutral, the electrons follow the magnetic field lines, which, in turn, allow that a new layer can be created (Haldoupis et al 2007). Generally, these winds are driven by diurnal, semidiurnal and terdiurnal tides present in the E region (Mathews 1998;Wilkinson et al 1992;Haldoupis 2011;Oikonomou et al 2014;Pignalberi et al 2014). These sporadic E layers are classified as blanketing layers (Es b ) (see, for example, Piggot and Rawer 1972) due to their capacity of (partially or totally) blocking the reflection of radio waves from the upper layers.…”

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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“…Hence, from a single ionogram it would not be possible to derive the dynamics of the ionospheric layers. On the contrary, the HTI analysis proposed by Haldoupis et al (2006), and recently used by Pignalberi et al (2014) and Oikonomou et al (2014), to investigate how tidal waves influence the Es dynamics, considers a specific frequency range and, by using a series of ionograms, allows the study of the aforementioned dynamics. The output of the HTI analysis is a plot of the intensity of the energy received by the ionosonde, after being reflected by the ionosphere, versus the 24 h of the day, for a definite frequency range, and for the same height range of the ionogram.…”

Section: Analysis and Resultsmentioning

confidence: 99%

20 March 2015 solar eclipse influence on sporadic E layer

Pezzopane

Pietrella

Pignalberi

et al. 2015

Advances in Space Research

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Sporadic E tidal variabilities and characteristics observed with the Cyprus Digisonde

Cited by 39 publications

References 47 publications

Quarterdiurnal signature in sporadic E occurrence rates and comparison with neutral wind shear

Quarterdiurnal signature in sporadic E occurrence rates and comparison with neutral wind shear

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

20 March 2015 solar eclipse influence on sporadic E layer

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