F Region Electric Field Effects on the Intermediate Layer Dynamics During the Evening Prereversal Enhancement at Equatorial Region Over Brazil

Santos, A. M.; Batista, I. S.; Brum, C. G. M.; Sobral, J. H. A.; Abdu, M. A.; Souza, J. R.

doi:10.1029/2020ja028429

Cited by 8 publications

(11 citation statements)

References 56 publications

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“…These results show that in general, the ILs occurrence resulted to be independent of the magnetic disturbances, since the referred two periods of geomagnetic activity are totally different from each other. However, their development/dynamics over Brazilian sector can be affected by disturbed electric fields, as shown by the results here presented and others previous publications (dos Santos et al 2019 andSantos et al 2021). Although the impacts of the geomagnetic activity on different layers of the ionosphere have been extensively studied, there is a lack of information about what happens in the ionospheric valley region during such conditions, mainly over the low and equatorial latitudes.…”

Section: Data Setsupporting

confidence: 55%

“…However, the larger descending rate (> 10 km/h) observed over the equatorial region may reveal an additional influence of the gravity waves in IL's dynamics. Additionally, Santos et al (2021) reported interesting events in which the ILs presented an upward movement at the same time in which the F layer rises due to the evening prereversal enhancement of the zonal electric field. Such characteristic was observed in most of the cases during a period of high solar activity, between October and April months, however a single case also was observed in 2009.…”

Section: F-regionmentioning

confidence: 99%

“…In all the events, the ILs were located at altitudes higher than or equal to 175 km, except the event of November 10, 2003, when an Es layer located at about 120 km of altitude presented an abrupt rise reaching 290 km of altitude in a time interval of ~ 1.25 hours. This rapid rise of the Es/IL layers probably was caused by an eastward electric field of ~ 0.6 mV/m arising from the PRE and the PPEF (for more details, see Santos et al, 2021).…”

Section: F-regionmentioning

confidence: 99%

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Intermediate Layers responses to Geomagnetic Activity During the 2009 Deep Solar Minimum Over the Brazilian Low Latitude Sector

Santos

Brum

Batista

et al. 2021

Preprint

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Abstract. Intermediate layers (ILs) are regions of enhanced electron density located in the ionospheric valley that extends from the peak altitude of the daytime E-region to the bottom side of the F-region. This work presents the daytime behavior of the ILs parameters (the virtual height - h’IL, and the top frequency - ftIL) over the low latitude region of Cachoeria Paulista (CP, 22.42° S; 45° W, I: −34.4°) for the deepest solar minimum of the last 500 years. In such a unique condition, this research reveals for the first time the ILs' quiet state seasonal behavior as well as its responses to moderate changes in the geomagnetic activity. The main results show that even small variations of geomagnetic activity (quantified by the planetary Kp index) are able to modify the dynamics of the ILs parameters. For the first time, it was observed that during the summer, the h’IL decrease rapidly with the increase of geomagnetic activity mainly in the early morning hours. In the following hours, a smoothed rise of the IL was found in all seasons analyzed. Regarding to frequency, it was observed that after 12:00 LT, there is a tendency of it decreased with the increase of the magnetic disturbances, being this characteristic more intense after 16:00 LT, except in the equinox, when little or no response was found during all the interval analyzed. In addition, it stands out that the annual periodicity of the ftIL was observed while the h’IL presents semiannual component.

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Section: Data Setsupporting

confidence: 55%

Section: F-regionmentioning

confidence: 99%

Section: F-regionmentioning

confidence: 99%

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Intermediate Layers responses to Geomagnetic Activity During the 2009 Deep Solar Minimum Over the Brazilian Low Latitude Sector

Santos

Brum

Batista

et al. 2021

Preprint

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“…Moreover, in addition to the vertical drift of the F layer, this study also shows the unique phenomenon of the E s layer being uplifting and moving downward near the center path of the moon shadow (Xiamen) during the solar eclipse (Figures 2b-2c). Santos et al (2021) analyzed the dynamics of the intermediate layer according to the ionosonde data of 357 days in 2003 and 293 days in 2009. However, they reported that the upward movement of the E s layer is a rare phenomenon under both geomagnetic quiet and disturbance conditions.…”

Section: Discussionmentioning

confidence: 99%

“…Santos et al. (2021) analyzed the dynamics of the intermediate layer according to the ionosonde data of 357 days in 2003 and 293 days in 2009. However, they reported that the upward movement of the E s layer is a rare phenomenon under both geomagnetic quiet and disturbance conditions.…”

Section: Discussionmentioning

confidence: 99%

Convergence Effects on the Ionosphere During and After the Annular Solar Eclipse on 21 June 2020

Wang

Sun

et al. 2022

JGR Space Physics

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A moon shadow passed through the region of eastern and southern China and ends near sunset (∼09:30 UT) under the solar minimum condition on 21 June 2020. It is an opportunity to study the ionospheric behaviors influenced by the solar eclipse at low latitudes. Wang et al. (2021) analyzed the behaviors of the sporadic-E (E s ) layer during the solar eclipse on 21 June 2020. The continuously upward and downward movement of the E s layer reveals a prominent transport process occurring in the vertical direction of the ionosphere during the obscuration.It is known that the transport effect dominants the F region during an eclipse (Dear et al., 2020;Rishbeth, 1970;Tsai & Liu, 1999). Dang et al. (2020) simulated the thermospheric and ionospheric responses to the annular solar eclipse on 21 June 2020 using a coupled thermosphere-ionosphere-electrodynamics model. They suggested that the solar eclipse could cause the total electron content (TEC) enhancement in the equatorial ionospheric anomaly (EIA) area for nearly 4.5 hr under the influence of the transequatorial plasma transport. Using the ground-and space-based observations, Zhang et al. ( 2020) and Huang et al. (2020) showed that the ionospheric responses to the annular solar eclipse, such as the disturbances of TEC, electron density and temperature, and maximum plasma density of F 2 layer (N m F 2 ), are much complicated at low latitudes. They suggested that the disturbed electric field, neutral winds, thermal conduction, interhemispheric photoelectron transport process, are mainly responsible for these complicated behaviors. Aa et al. ( 2021) also observed these similar ionospheric behaviors and suggested that the perturbations in the field-aligned thermal conduction during the solar eclipse lead to the possible interconnections between the eclipse and the conjugate ionospheres. Sun et al. (2021) analyzed the TEC data from the ground-based Global Navigation Satellite System (GNSS) receivers over east and south Asia as well as the ionospheric F 2 layer critical frequency (f o F 2 ) and its height (h m F 2 ) recorded by the ionosonde at Puer (22.7°N, 101.05°E, 72% obscuration) on 21 June 2020. Their results showed that the eclipse-induced TEC perturbations behave as a large-scale terminator wave propagating northwestward after sunset. The previous studies comprehensively examined the effects of the eclipse on the ionosphere. However, the effect of the vertical plasma drifts on the F-layer induced by this solar eclipse was not clearly identified yet.

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E‐Field Effects on Day‐To‐Day Variations of Geomagnetic Mid‐Latitude Sporadic E Layers

2023

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According to this theory, above ∼130 km, meridional-wind shears create EsLs by an ion-neutral frictional force along the geomagnetic fields. Below ∼130 km, zonal-wind shears create EsLs by the vertical Lorentz force with northward geomagnetic fields.Mathews (1998) proposed the generalized wind shear theory, which considers both wind and E-field effects on EsLs. E-fields play a key role in the EsL dynamics at geomagnetic high, low, and equatorial latitudes. At geomagnetic high-latitudes, E-fields originating from the magnetosphere are crucial for EsL formations (Kirkwood & Nilsson, 2000). At geomagnetic equatorial latitudes, Es is detected as a scattering of the radio signals in daytime ionograms, which is called Esq (e.g., Rastogi, 1972;Resende et al., 2018). Type II irregularities in the equatorial electrojet account for formations of the Esqs, but the wind shear theory does not. However, especially in the Brazilian equatorial sector, some EsLs can occur owing to the wind-driven mechanisms. The EsLs are called the blanketing EsLs and affected by both E-fields and winds (

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F Region Electric Field Effects on the Intermediate Layer Dynamics During the Evening Prereversal Enhancement at Equatorial Region Over Brazil

Cited by 8 publications

References 56 publications

Intermediate Layers responses to Geomagnetic Activity During the 2009 Deep Solar Minimum Over the Brazilian Low Latitude Sector

Intermediate Layers responses to Geomagnetic Activity During the 2009 Deep Solar Minimum Over the Brazilian Low Latitude Sector

Convergence Effects on the Ionosphere During and After the Annular Solar Eclipse on 21 June 2020

E‐Field Effects on Day‐To‐Day Variations of Geomagnetic Mid‐Latitude Sporadic E Layers

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