IMF-By dependence of transient ionospheric flow perturbation associated with sudden impulses: SuperDARN observations

Hori, Tomoaki; Shinbori, Atsuki; Fujita, Shigeru; Нишитани, Н.

doi:10.1186/s40623-015-0360-6

Cited by 9 publications

(20 citation statements)

References 31 publications

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“…Effects of the passage of TCVs are also seen at mid-latitudes in ground scatter returns, as shown by Kim et al (2012). Meanwhile, Hori et al (2015) demonstrated using the high-and mid-latitude SuperDARN data that there is a dawn-dusk asymmetry of flow vortices as shown in statistical convection velocity perturbations, caused by IMF By polarity, which appears associated with negative SI events (dynamic pressure decrease) that is not seen for positive SI events. However, most of the observations were poleward of 60°M LAT, and all measurements were considered not just those associated with TCVs.…”

Section: Transientsmentioning

confidence: 89%

Review of the accomplishments of mid-latitude Super Dual Auroral Radar Network (SuperDARN) HF radars

Watanabe

Ruohoniemi

Lester

et al. 2019

Prog Earth Planet Sci

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175

166

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The Super Dual Auroral Radar Network (SuperDARN) is a network of high-frequency (HF) radars located in the high-and mid-latitude regions of both hemispheres that is operated under international cooperation. The network was originally designed for monitoring the dynamics of the ionosphere and upper atmosphere in the high-latitude regions. However, over the last approximately 15 years, SuperDARN has expanded into the mid-latitude regions. With radar coverage that now extends continuously from auroral to sub-auroral and mid-latitudes, a wide variety of new scientific findings have been obtained. In this paper, the background of mid-latitude SuperDARN is presented at first. Then, the accomplishments made with mid-latitude SuperDARN radars are reviewed in five specified scientific and technical areas: convection, ionospheric irregularities, HF propagation analysis, ion-neutral interactions, and magnetohydrodynamic (MHD) waves. Finally, the present status of mid-latitude SuperDARN is updated and directions for future research are discussed.

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Section: Transientsmentioning

confidence: 89%

Review of the accomplishments of mid-latitude Super Dual Auroral Radar Network (SuperDARN) HF radars

Watanabe

Ruohoniemi

Lester

et al. 2019

Prog Earth Planet Sci

Self Cite

175

166

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“…J C connects with J MP to form a current loop. Due to the enhanced current within this loop, the vertical component of the Earth’s magnetic field increases (by a factor b in Figure 1a); this results in a well observed rapid positive increase in SYM‐H (e.g., Hori et al., 2015; Takeuchi et al., 2002).…”

Section: Introductionmentioning

confidence: 90%

“…Hori et al. (2015) define the SC signature in SYM‐H as an increase of more than 5 nT with a gradient greater than about 15 nT per 10 s. Given the magnitude of the pressure change, SIs can have a remarkably dramatic impact on the Earth’s magnetosphere, and the electrodynamics within.…”

Section: Introductionmentioning

confidence: 99%

“…Either way, such particle precipitation increases the ionospheric electron and ion densities and can seed F region irregularities, affecting SuperDARN backscatter returns. Positive SIs can result in enhancements in the twin cell flow, particularly the strength of antisunwards flow in the noon sector (Gillies et al., 2012; Hori et al., 2015). Conversely, Hori et al.…”

Section: Introductionmentioning

confidence: 99%

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Multi‐Instrument Observations of the Effects of a Solar Wind Pressure Pulse on the High Latitude Ionosphere: A Detailed Case Study of a Geomagnetic Sudden Impulse

et al. 2023

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The terrestrial magnetosphere-ionosphere system is strongly coupled to the solar wind, which is highly variable on short timescales. Near-step changes in solar wind dynamic pressure, known as pressure pulses which when positive, can rapidly excite and restructure the electrodynamics within the magnetosphere-ionosphere system. When the effects of a rapid change in solar wind dynamic pressure are communicated into the magnetosphere, this is known as a geomagnetic sudden commencement (SC, Araki, 1994), indicated by a corresponding step change in the ring current index SYM-H (e.g., Hori et al., 2015;Takeuchi et al., 2002). SCs can be further subdivided into two categories: sudden impulses (SIs) and sudden storm commencements (SSCs). Although the definition of these three terms (SC, SI and SSC) is not always consistent in the literature, in this paper an SSC is defined as an SC which is rapidly (within 12 hr (Taylor et al., 1994)) followed by a geomagnetic storm, otherwise it is an SI.The majority of pressure pulses observed in the solar wind are caused by dramatic phenomena such as coronal mass ejections (CMEs) or corotating interaction regions (CIRS, e.g., Zuo et al., 2015). CMEs are violent eruptions of plasma from the Sun, resulting from magnetic reconnection (e.g., Hundhausen, 1995) and can cause SSCs (Taylor et al., 1994). CIRs, also called fast-slow stream interaction regions, have steep pressure gradients resulting from fast flowing plasma catching up with more slowly rotating plasma on more tightly wound magnetic field lines (e.g., Hundhausen, 1995). CIRs can cause Storm Gradual Commencements (SGCs, Taylor et al., 1994), which are geomagnetic storms not related to an SC. If there is no subsequent storm, a positive SI (+SI) may result from an increase in pressure, and a negative SI (−SI) may result from a decrease in pressure. An SI is generally considered to be driven by a pressure change of at least 3 nPa in under 10 min (e.g., Coco et al., 2011), although it can also be identified with SYM-H (e.g., Hori et al., 2015). Hori et al. (2015) define the SC signature in SYM-H as an increase of more than 5 nT with a gradient greater than about 15 nT per 10 s. Given the magnitude of the pressure change, SIs can have a remarkably dramatic impact on the Earth's magnetosphere, and the electrodynamics within.

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“…Therefore, the present study further confirms the penetration of dawn-to-dusk convection electric field to equatorial altitudes in response to sudden enhancements in solar wind density alone without any significant changes in the velocity and IEFy. Further, this study also showcases the PPEFs of opposite polarity in response to sharp reduction in the density, probably due to sudden reduction in convection electric fields in order to adjust for the rarefied state of magnetosphere (Araki & Nagano, 1988;Hori et al, 2015).…”

Section: 1029/2020ja027869mentioning

confidence: 56%

The Solar Wind Density Control on the Prompt Penetration Electric Field and Equatorial Electrojet

Nilam¹,

Ram²,

Shiokawa

et al. 2020

JGR Space Physics

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Prompt penetration of convection/overshielding electric fields to equatorial and low latitudes during the southward/northward turnings of interplanetary magnetic field (IMF Bz) have been widely studied in the literature. The other types of penetration electric fields due to sudden changes in the solar wind dynamic pressure, IMF By and during the onset of substorms have also been recently reported. In this paper, we present the exclusive role of solar wind density changes on the prompt equatorial electric field disturbances using the long-term observations of equatorial electrojet (EEJ) from the Indian sector. In response to the sharp increases in the solar wind density, prompt increases/decreases in the EEJ indicating the eastward/westward prompt penetration electric field (PPEF) of~20 min periods have been consistently observed on the dayside/nightside. The prompt equatorial electric field disturbances of the opposite polarity have also been observed when the density decreases sharply. Further, the polarity of these PPEF disturbances does not show any clear dependency on the direction of IMF Bz and By. This paper is the first report with a statistically significant number of observations on the characteristics of equatorial electric field disturbances in response to the sudden enhancements/decreases in the solar wind density alone on both dayside and nightside. The underlying physical mechanisms for the prompt equatorial electric field disturbances have been discussed in light of enhanced high-latitude convection and additional field-aligned currents due to sudden enhancement of solar wind density.

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IMF-By dependence of transient ionospheric flow perturbation associated with sudden impulses: SuperDARN observations

Cited by 9 publications

References 31 publications

Review of the accomplishments of mid-latitude Super Dual Auroral Radar Network (SuperDARN) HF radars

Review of the accomplishments of mid-latitude Super Dual Auroral Radar Network (SuperDARN) HF radars

Multi‐Instrument Observations of the Effects of a Solar Wind Pressure Pulse on the High Latitude Ionosphere: A Detailed Case Study of a Geomagnetic Sudden Impulse

The Solar Wind Density Control on the Prompt Penetration Electric Field and Equatorial Electrojet

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