Equatorial ionization anomaly in the low‐latitude topside ionosphere: Local time evolution and longitudinal difference

Chen, Yiding; Liu, Libo; Le, Huijun; Wan, Weixing; Zhang, Hui

doi:10.1002/2016ja022394

Cited by 34 publications

(44 citation statements)

References 63 publications

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“…The gray line indicates the dip equator. Zonal neutral wind U n is generally westward during the daytime in all three seasons (Chen et al, ; Ren et al, ). Trans‐equator neutral wind V n is southward during the June solstice and northward during the December solstice.…”

Section: Discussionmentioning

confidence: 99%

“…On the other hand, the seasonal variation of the relative location of the subsolar point and the magnetic equator might alter the plasma ambipolar diffusion rates. The geomagnetic field configuration also plays an important role in transferring plasma from one hemisphere to another by pushing the plasma up in one hemisphere and down in the opposite hemisphere (Chen et al, ; Lin, Hsiao, et al, ). The interhemispheric asymmetry has also been studied by using the physics‐based National Center for Atmospheric Research Thermosphere‐Ionosphere Electrodynamics Global Circulation Model.…”

Section: Introductionmentioning

confidence: 99%

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Transition of Interhemispheric Asymmetry of Equatorial Ionization Anomaly During Solstices

Huang

Liu

et al. 2018

JGR Space Physics

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The magnitudes of the two crests of equatorial ionization anomaly (EIA) vary with local time. During the solstices, EIA crest in the winter hemisphere is larger than that in the summer hemisphere before noon/early afternoon. Whereafter, the crest in the summer hemisphere becomes intensified, and the stronger EIA crest transits to the summer hemisphere. Using Constellation Observing System for Meteorology, Ionosphere, and Climate ionospheric radio occultation data, we examine the longitudinal and altitudinal variations of this interhemispheric transition in four longitudinal sectors and at seven heights under low/high solar activity conditions. The results show that during the June solstice the transition of the stronger EIA peak from the winter to the summer hemisphere is earlier in the sectors where the geomagnetic equator is further away from the subsolar point and the geomagnetic field declination is larger, while during the December solstice the longitudinal variations generally show the opposite compared with that in the June solstice. The distance between the geomagnetic equator and subsolar point and the geomagnetic field configuration control the upward/downward plasma movements in the summer/winter hemisphere, leading to the different transition times in different longitudinal sectors. For both solstices, transition times emerge earlier as height increases, which is mainly caused by the larger effective scale height in the summer hemisphere than in the winter hemisphere, resulting in a smaller electron density difference at higher altitudes with a fast transition. Solar activity alters the transition time below 320 km, whereas it has no evident effect at higher altitudes.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Transition of Interhemispheric Asymmetry of Equatorial Ionization Anomaly During Solstices

Huang

Liu

et al. 2018

JGR Space Physics

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“…Chen YD et al (2016a) investigated the latitudinal structure of topside ion density ( N i ) using ROCSAT‐1 and DMSP N i observations. The double‐peak structure of EIA may exist at 600 km but is not a prevalent characteristic at 840 km, even at solar maximum sunset hours.…”

Section: Ionospheric Climatology and Modellingmentioning

confidence: 99%

Chinese ionospheric investigations in 2016–2017

Liu

Wan

2018

Earth and Planetary Physics

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After the release of the previous report to the Committee on Space Research (COSPAR) on progress achieved by Chinese scientists in ionospheric researches (Liu LB and Wan WX, 2016), in the recent two years (2016–2017) many interesting new investigations into various ionospheric related issues have been completed. In this report, about 100 publications are summarized. The topics highlighted are as follows: Ionospheric space weather, ionospheric dynamics, ionospheric climatology and modelling, ionospheric irregularity and scintillation, Global Navigation Satellite System (GNSS) related ionospheric issues and other techniques, and radio wave propagation in the ionosphere. An outstanding feature is that more and more observations from the Meridional Project supported the ionospheric investigations.

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“…At higher altitudes, diffusion is the leading physical process, whereas the loss mechanism is more dominant process at the lower F region altitudes. The equatorial zonal electric field along with the horizontal magnetic field lines at the geomagnetic equator creates the so-called "equatorial plasma fountain (EPF)" resulting in the formation of the EIA (Balan & Bailey, 1995;Bramley & Peart, 1965;Chen et al, 2016;Lu et al, 2012;Moffett & Hanson, 1965). With various anomalies, the spatial and temporal variation of N m F 2 is different compared to the electron density distribution in E and F 1 layers of the ionosphere.…”

Section: Introductionmentioning

confidence: 99%

Variation of the Equatorial Height Anomaly During the Main Phase of 2015 St. Patrick's Day Geomagnetic Storm Using ANNIM and TIEGCM

et al. 2019

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A double‐peak structure in the peak height of ionospheric F2 layer around ±10o geomagnetic latitudes similar to the equatorial ionization anomaly was recently reported. This unique feature was referred as the equatorial height anomaly (EHA). In the present paper, a simulation study is carried out using the data‐driven artificial neural network‐based two‐dimensional ionospheric model (ANNIM‐2D) and the physics‐based thermosphere‐ionosphere‐electrodynamics general circulation model (TIEGCM) to understand the local time and latitudinal variation of EHA during the main phase of St. Patrick's Day geomagnetic storm. Both the ANNIM‐2D and TIEGCM consistently show pronounced EHA during the main phase of the geomagnetic storm. Further, the local time of EHA development on the storm day is much earlier (nearly 2 hr) than the quiet time over Brazilian sector (90°W). The TIEGCM simulation revealed that the storm time enhancement of the equatorial fountain associated with the enhanced equatorial zonal electric field is the main controlling factor for the pronounced EHA during the main phase. The storm time meridional neutral winds positively contribute to the development of EHA. This study revealed the direct manifestation of the storm time‐enhanced plasma fountain on the EHA.

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Equatorial ionization anomaly in the low‐latitude topside ionosphere: Local time evolution and longitudinal difference

Cited by 34 publications

References 63 publications

Transition of Interhemispheric Asymmetry of Equatorial Ionization Anomaly During Solstices

Transition of Interhemispheric Asymmetry of Equatorial Ionization Anomaly During Solstices

Chinese ionospheric investigations in 2016–2017

Variation of the Equatorial Height Anomaly During the Main Phase of 2015 St. Patrick's Day Geomagnetic Storm Using ANNIM and TIEGCM

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