New Features of the Enhancements in Electron Density at Low Latitudes

Liu, Libo; Zhang, Ding; Le, Huijun; Chen, Yiding; Zhang, Hui; Wu, Jian; Li, Guozhu; Wan, Weixing

doi:10.1029/2019ja027539

Cited by 15 publications

(16 citation statements)

References 33 publications

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“…Moreover, the Ne altitudinal profile continuously becomes thinner, and the Chapman scale height reduces at the F2-layer peak height at Sanya during the enhancements. Similar features are also demonstrated in the Ne observations of the incoherent scatter radar at Qujing (103.8°E, 25.6°N), another low latitude station in China, in the afternoon and sunset hours (L. Liu et al, 2020).…”

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Structure of Post‐Midnight Enhancements in Electron Density at the Low Latitude F‐Layer Ionosphere

et al. 2023

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It has previously found that at Sanya (109.6°E, 18.3°N) a post‐midnight enhancement in the F2‐layer peak electron density (NmF2) is often accompanied by the increase in the bottom side F layer electron density (Ne) and a reduction in the top side F layer Ne. We conduct a case study to explore the complete spatial coverage of the post‐midnight enhancements of electron density in the low latitude ionosphere. The total electron content (TEC) data are retrieved from the Beidou Geostationary Earth Orbit (GEO) satellite signals recorded by a network of Global Navigation Satellite System (GNSS) receivers in Asia‐Australia. The F2‐layer peak parameters and the altitudinal profiles of Ne are measured by the ionosonde, and incoherent scatter radar at Sanya (109.6°E, 18.3°N). The GEO‐TEC does not always completely follow the enhancement of NmF2. The enhancements may peak roughly simultaneously or with significant time shifts in the west‐east direction, even in the GEO‐TEC series recorded by a GNSS receiver in an event, which indicates possibly the enhancement of different longitudinal scales. Further, in the cases the enhancement is clustered in a limited area. The low latitude enhancements show a hemispheric asymmetry; they occur mainly in the northern hemisphere and usually have no correspondingly magnetic conjugate symmetrical features in the southern hemisphere. The hemispheric asymmetry of the enhancements highlights that both the field‐aligned plasma transport and electric fields are possibly responsible for regulating the limited spatial presence of post‐midnight enhancements in the low latitude ionosphere.

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confidence: 82%

Structure of Post‐Midnight Enhancements in Electron Density at the Low Latitude F‐Layer Ionosphere

et al. 2023

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“…Besides the large‐ and small‐scale ionospheric variations, the background ionospheric total electron content (TEC) often shows sudden enhancements embedded in the daily variation during various LT periods on geomagnetic quiet days (e.g., Balan et al, 1994; Liu et al, 2013, 2020; Luan et al, 2008). The ionospheric variations with various temporal and spatial scales cannot be explored with a single type of instrument at a single station, because it suffers the narrow field of view, missing the opportunity to witness the evolution of ionospheric disturbances in a broader horizon including when, where, and how they are generated.…”

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confidence: 99%

IONISE: An Ionospheric Observational Network for Irregularity and Scintillation in East and Southeast Asia

Dou

et al. 2020

JGR Space Physics

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An Ionospheric Observational Network for Irregularity and Scintillation in East and Southeast Asia (IONISE) is developed to identify and study the short‐term and fine‐scale ionospheric variations over China. The IONISE network mainly includes three crossed chains of Beidou geostationary satellite total electron content (TEC)/scintillation receivers along 110°E, 23°N, and 40°N respectively, multistatic portable digital ionosondes and bistatic very high‐frequency radars. Based on the IONISE observations, we report some preliminary results of ionospheric disturbances and irregularities, including (1) initially generated and zonally drifting equatorial plasma bubbles and related scintillations, (2) traveling ionospheric disturbances from middle to low latitudes, (3) drift of strong sporadic E structures over a wide area of more than 1,000 km, (4) fine‐scale ionospheric perturbation and regional TEC gradient, and (5) general features of ionospheric response to geomagnetic storms. Possible mechanisms responsible for these ionospheric phenomena are discussed. The IONISE provides new data set for investigation on ionospheric disturbances of various scales in a broad region with dense observations along specific latitude/longitude.

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“…Once upward vertical drift becomes significant before the prolonged photoionization termination in summer, the electron density could increase (Rishbeth, 1967(Rishbeth, , 1968. By contrast, it is still an unsolved question of how hmF2 changes during winter INEs and whether hmF2 variations play an important role in the formation of winter INE (e.g., Liu et al, 2020). In this study, we collected two ionosondes data in the middle latitude region and Jet Propulsion Laboratory (JPL) total electron content (TEC) maps during the 24th solar cycle to investigate INEs.…”

Section: Introductionmentioning

confidence: 99%

A Statistical Study on the Winter Ionospheric Nighttime Enhancement at Middle Latitudes in the Northern Hemisphere

Chen

Liu

et al. 2020

JGR Space Physics

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The ionospheric electron density generally decreases after sunset under the effect of recombination, but sometimes, it increases, which forms an ionospheric nighttime enhancement (INE). In this research, the observations from two ionosondes in Mohe and Beijing and NASA's Jet Propulsion Laboratory‐Global Ionosphere Maps during the 24th solar cycle were used to explore the feature and mechanism of INE at midlatitudes. It shows that hmF2 always increases when INE occurs in summer, while it either rises or falls in winter. The increase of hmF2 has a significant contribution to INE in summer. For winter INE, however, the hmF2‐rising and the hmF2‐declining type INEs present no significant differences in durations and amplitudes, except that the former occurs slightly earlier than the latter. This suggests that the uplift of the ionosphere induced by equatorward thermospheric wind may not be a dominant factor for controlling the formation of winter INE at midlatitudes. We found that the electron density difference between the summer hemisphere and the winter hemisphere trends increases when the INE occurs in the winter hemisphere. This increased electron density difference between the two hemispheres is beneficial to the summer‐to‐winter interhemispheric plasma transport and the formation of INE in winter. Meanwhile, it is likely that the ionospheric equivalent slab thickness decreases during the winter INE due to downward transport from the topside. These indicate that downward plasma influxes from the topside ionosphere and the conjugate summer hemisphere play dominant roles for the formation of winter INE at middle latitudes.

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New Features of the Enhancements in Electron Density at Low Latitudes

Cited by 15 publications

References 33 publications

Structure of Post‐Midnight Enhancements in Electron Density at the Low Latitude F‐Layer Ionosphere

Structure of Post‐Midnight Enhancements in Electron Density at the Low Latitude F‐Layer Ionosphere

IONISE: An Ionospheric Observational Network for Irregularity and Scintillation in East and Southeast Asia

A Statistical Study on the Winter Ionospheric Nighttime Enhancement at Middle Latitudes in the Northern Hemisphere

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