GPS Scintillations and TEC Variations in Association With a Polar Cap Arc

Wang, Yong; Cao, Zheng; Zou, Xing; Zhang, Q.; Jayachandran, P. T.; Oksavik, K.; Balan, N.; Shiokawa, K.

doi:10.1029/2020ja028968

Cited by 9 publications

(7 citation statements)

References 62 publications

(127 reference statements)

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“…Underlying solar wind and Interplanetary Magnetic Field (IMF) conditions were extracted from the OMNI-2 website, which all had already been time-shifted to the nose of bow shock. To account for the propagation delay of solar wind and IMF changes from the nose of bow shock to the polar ionosphere, an additional 7 min was added, which is consistent with the previous results (e.g., Liou et al, 1998;Wang, Cao, et al, 2021). The variation of magnetic field at Resolute Bay is provided by the Resolute magnetometer, which was obtained from the SuperMAG, as well as the auroral electrojet indices of SME/SMU/SML (Newell & Gjerloev, 2011a).…”

Section: Instrumentsmentioning

confidence: 68%

Simultaneous Observations of a Polar Cap Sporadic‐E Layer by Twin Incoherent Scatter Radars at Resolute

et al. 2022

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At high latitudes, the Sporadic‐E layer (Es layer) is a common phenomenon but is still poorly understood due to sparse measurements and the difficulty of conventional mechanisms to operate. In this study, an interesting case of polar cap Es layer is first studied by using the twin incoherent scatter radars (northward‐looking face of Resolute Incoherent‐Scatter Radar and Resolute Incoherent‐Scatter Radar‐Canada), a Canadian Advanced Digital Ionosonde, and a Magnetometer, all at Resolute, Canada. From several electron density profiles of the twin radars, the horizontal scale of the polar cap Es layer is found to be greater than 350 km. Moreover, the polar cap Es layer is determined to be drifting from the bottom F region (>150 km) to the lower E region. Furthermore, a unique appearance of double polar cap Es layers is observed. As a result, these peculiar signatures inspire a newly proposed process that involves the combination of localized electric fields and gravity waves.

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Section: Instrumentsmentioning

confidence: 68%

Simultaneous Observations of a Polar Cap Sporadic‐E Layer by Twin Incoherent Scatter Radars at Resolute

et al. 2022

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“…For the purpose of our work, we decided to consider scintillation data at a better time resolution, that is, use a shorter running window of 1 s. Functions used to calculate the S 4 and σ ϕ index, with a running window of 1 s (50 data points, due to the 50 Hz sampling resolution), are shown in Supporting Information S1. Such an approach has been proven to be more effective in detecting small-scale irregularities triggered by the auroral particle precipitation (Materassi & Mitchell, 2007;Wang et al, 2021), which are otherwise almost absent when considered on the standard 1-min basis (see, e.g., the climatological results provided in Alfonsi et al (2011), De Franceschi et al (2019, Moen et al (2013), andSpogli et al (2009)). According to what is reported in Forte and Radicella (2002) and in their Equations 6 and 7, some scintillation indices at 1 s allow studying spatial scales of the irregularities that are below 100 m, that is, below the Fresnel's scale, and are able to account for spatial variability of particle precipitation patterns.…”

Section: Approach and Data Selectionmentioning

confidence: 99%

Section: Approach and Data Selectionmentioning

confidence: 99%

Investigation of Ionospheric Small‐Scale Plasma Structures Associated With Particle Precipitation

Enengl,

Spogli,

Kotova

et al. 2024

Space Weather

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We investigate the role of auroral particle precipitation in small‐scale (below hundreds of meters) plasma structuring in the auroral ionosphere over the Arctic. In this scope, we analyze together data recorded by an Ionospheric Scintillation Monitor Receiver (ISMR) of Global Navigation Satellite System (GNSS) signals and by an All‐Sky Imager located in Longyearbyen, Svalbard (Norway). We leverage on the raw GNSS samples provided at 50 Hz by the ISMR to evaluate amplitude and phase scintillation indices at 1 s time resolution and the Ionosphere‐Free Linear Combination at 20 ms time resolution. The simultaneous use of the 1 s GNSS‐based scintillation indices allows identifying the scale size of the irregularities involved in plasma structuring in the range of small (up to few hundreds of meters) and medium‐scale size ranges (up to few kilometers) for GNSS frequencies and observational geometry. Additionally, they allow identifying the diffractive and refractive nature of fluctuations on the recorded GNSS signals. Six strong auroral events and their effects on plasma structuring are studied. Plasma structuring down to scales of hundreds of meters is seen when strong gradients in auroral emissions at 557.7 nm cross the line of sight between the GNSS satellite and receiver. Local magnetic field measurements confirm small‐scale structuring processes coinciding with intensification of ionospheric currents. Since 557.7 nm emissions primarily originate from the ionospheric E‐region, plasma instabilities from particle precipitation at E‐region altitudes are considered to be responsible for the signatures of small‐scale plasma structuring highlighted in the GNSS scintillation data.

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“…In addition to substorm aurora, scintillation is enhanced near the poleward boundary of the auroral oval, particularly when polar cap patches interact with the nightside auroral oval (Jin et al., 2016; van der Meeren et al., 2015). Polar cap arcs are also associated with scintillation (Jayachandran et al., 2017; Wang et al., 2021). The scintillation tends to occur on the leading and trailing edges of auroral forms, suggesting that density irregularities develop at density gradients that are created by particle precipitation (Loucks et al., 2017; Mrak et al., 2018; Mushini et al., 2018; Semeter et al., 2017; van der Meeren et al., 2015).…”

Section: Introductionmentioning

confidence: 99%

Nightside High‐Latitude Phase and Amplitude Scintillation During a Substorm Using 1‐Second Scintillation Indices

et al. 2023

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We examined evolution of Global Positioning System (GPS) scintillation during a substorm in the nightside high latitude ionosphere, using 1‐second phase and amplitude scintillation indices from the Canadian High Arctic Ionospheric Network (CHAIN) network. The traditional 1‐minute scintillation indices showed that the phase scintillation was dominant, while the amplitude scintillation was weak. However, the 1‐second amplitude scintillation occurred more often in association with major auroral structures (polar cap arc, growth phase arc, onset arc, poleward expanding arc, poleward boundary intensification, and diffuse aurora) that were detected by the THEMIS all‐sky imagers (ASIs). The 1‐minute index missed much of the amplitude fluctuations because they only lasted ∼10 seconds near a local peak or at the gradients of the auroral structures. The 1‐second phase scintillation was concurrent with the amplitude scintillation but was much weaker than the 1‐minute phase scintillation. The frequency spectral analysis showed that the spectral power above ∼1 Hz was diffractive and below ∼1 Hz was refractive. We suggest that the amplitude scintillation in the high‐latitude ionosphere is much more common than previously considered, and that a short time window of the order of 1 second should be used to detect the scintillation. The 1‐minute phase scintillation index is largely influenced by refractive effects due to total electron content (TEC) variations, and the spectral power below ∼1 Hz should be removed to identify diffractive scintillation.

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GPS Scintillations and TEC Variations in Association With a Polar Cap Arc

Abstract: In the polar ionosphere, different types of large-scale irregularities are often generated, such as the polar cap patch (e.g.

Cited by 9 publications

References 62 publications

Simultaneous Observations of a Polar Cap Sporadic‐E Layer by Twin Incoherent Scatter Radars at Resolute

Simultaneous Observations of a Polar Cap Sporadic‐E Layer by Twin Incoherent Scatter Radars at Resolute

Investigation of Ionospheric Small‐Scale Plasma Structures Associated With Particle Precipitation

Nightside High‐Latitude Phase and Amplitude Scintillation During a Substorm Using 1‐Second Scintillation Indices

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