Geomagnetic and solar activity dependence of ionospheric upflowing O+: FAST observations

Zhao, Kai; Jiang, Yong; Chen, K. W.; Linfeng, Huang

doi:10.1007/s10509-016-2872-3

Cited by 6 publications

(14 citation statements)

References 53 publications

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“…Using DE‐1 observations, Yau et al () observed that the occurrences of ionospheric upflows actually correlate well to solar activity (the indicator is the solar radio flux at 10.7 cm in their paper), the O + UFI (upflowing ionospheric ion) displayed a factor of 2–3 increase in the occurrence rates at solar maximum. Similar results were obtained by Zhao et al (). Using FAST observations, they made a statistical analysis on the occurrence rates of upflowing 5 eV–12 keV O + ions.…”

Section: Introductionsupporting

confidence: 92%

“…Yau et al () concluded that the intensity of O + outflows at solar maxima was double the intensity at solar minima, using DE‐1 observations. Zhao et al () reported a consistent result using FAST observations and concluded that the occurrence frequency of O + upflows during the first 3 years at solar maxima is 2.55–2.80 times that during solar minima.…”

Section: Discussionmentioning

confidence: 60%

“…This requires us to modify our statistical model if high‐ and low‐energy upflows dominate their source regions at different latitudes. Using FAST observations, Zhao et al () reported that the high‐energy (1 keV–12 keV) O + upflows escape predominantly from the nightside auroral zone, while low‐energy (5 eV–1 keV) O + upflows are more frequent in the dayside cusp region.…”

Section: Discussionmentioning

confidence: 99%

“…As a result, high‐energy O + upflows show a single peak in the occurrence frequency in the auroral oval zone while low‐energy upflows show two distinct peaks in the auroral oval zone and polar cusp region. Zhao et al () calculated the single peak to be at a latitude of ~62° MLAT and the two individual peaks at ~60° MLAT and 75°–78° MLAT. In this case, the Gaussian Mixture Model is not suitable for fitting high‐energy (1 keV–12 keV) O + upflows.…”

Section: Discussionmentioning

confidence: 99%

“…As a significant contributor to ion heating at low altitudes, heating by soft electron precipitations accelerates upflows over latitudes from 65° to 75° MLAT. Although the magnetic latitude of the ion upflow source region moves equatorially during magnetically disturbed times, Zhao et al () concluded that the occurrence rate decreases as the latitude moves away from the latitudes of peak occurrence rates.…”

Section: Introductionmentioning

confidence: 99%

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Latitude Dependence of Low‐Altitude O⁺ Ion Upflow: Statistical Results From FAST Observations

et al. 2017

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We introduce a statistical model to explain the latitudinal dependence of the occurrence rate and energy flux of the ionospheric escaping ions, taking advantage of advances in the spatial coverage and accuracy of FAST observations. We use a weighted piecewise Gaussian function to fit the dependence, because two probability peaks are located in the dayside polar cusp source region and the nightside auroral oval zone source region. The statistical results show that (1) the Gaussian Mixture Model suitably describes the dayside polar cusp upflows, and the dayside and the nightside auroral oval zone upflows. (2) The magnetic latitudes of the ionospheric upflow source regions expand toward the magnetic equator as Kp increases, from 81° magnetic latitude (MLAT) (cusp upflows) and 63° MLAT (auroral oval upflows) during quiet times to 76° MLAT and 61° MLAT, respectively. (3) The dayside polar cusp region provides only 3–5% O+ upflows among all the source regions, which include the dayside auroral oval zone, dayside polar cusp, nightside auroral oval zone, and even the polar cap. However, observations show that more than 70% of upflows occur in the auroral oval zone and that the occurrence probability increases at the altitudes of 3500–4200 km, which is considered to be the lower altitude boundary of ion beams. This observed result suggests that soft electron precipitation and transverse wave heating are the most efficient ion energization/acceleration mechanisms at the altitudes of FAST orbit, and that the parallel acceleration caused by field‐aligned potential drops becomes effective above that altitude.

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Section: Introductionsupporting

confidence: 92%

Section: Discussionmentioning

confidence: 60%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Latitude Dependence of Low‐Altitude O⁺ Ion Upflow: Statistical Results From FAST Observations

et al. 2017

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Characteristics of the Occurrence of Ion Upflow in Association With Ion/Electron Heating in the Polar Ionosphere

Jee

Lee

2019

JGR Space Physics

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We investigate the statistical characteristics of the ion upflow occurrence in association with ion and electron heatings in the polar ionosphere using the European Incoherent Scatter Svalbard Radar during the period of 2000–2015. The ion upflow events are classified as four types: with ion temperature increase (Type 1), with electron temperature increase (Type 2), with both ion and electron temperature increases (Type 3), and without any temperature increase (Type 4). These four types of upflow events are statistically analyzed with various geophysical conditions. We found that the overall occurrence of ion upflow is highest for Type 3 and then followed by Type 2, Type 1, and Type 4. This result indicates that the ion upflow is highly associated with soft particle precipitation induced electron heating, which becomes more effective with simultaneous friction induced ion heating. The statistical characteristics of ion upflow is summarized as follows: (1) It is most highly distributed in the daytime with a double peak structure but a deep minimum at dusk, (2) the highest occurrence appears at about 350‐ to 450‐km altitude for most of local time but extended to higher altitude near the magnetic local noon, (3) the ions mostly reach only up to about 200 km above their initiated altitudes, (4) it tends to increase with magnetic activity, particularly during the daytime, but (5) decreases and distributed at higher altitude with increasing solar activity, and (6) finally, the maximum occurrence appears in December solstice but the minimum in June solstice for most of local times.

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Statistical Study of the Relationship Between Ion Upflow and Field‐Aligned Current in the Topside Ionosphere for Both Hemispheres During Geomagnetic Disturbed and Quiet Time

Zhang

Jayachandran

et al. 2020

JGR Space Physics

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A statistical study of ion upflow and field-aligned currents (FACs) has been performed in the topside ionosphere of both hemispheres for magnetic quiet and disturbed times by using DMSP satellite observations from 2010-2013. Distributions in MLT/MLat reveal that ion upflow occurrence shows a dawn-dusk asymmetry distribution that matches well with the Region 1 FACs. In addition, there are highest occurrence regions near noon and within the midnight auroral disturbance area, corresponding to dayside cusp and nightside auroral disturbance regions, respectively. Both the ion upflow occurrence and FAC regions expand equatorward to a wider area during disturbed times.

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Geomagnetic and solar activity dependence of ionospheric upflowing O+: FAST observations

Cited by 6 publications

References 53 publications

Latitude Dependence of Low‐Altitude O⁺ Ion Upflow: Statistical Results From FAST Observations

Latitude Dependence of Low‐Altitude O⁺ Ion Upflow: Statistical Results From FAST Observations

Characteristics of the Occurrence of Ion Upflow in Association With Ion/Electron Heating in the Polar Ionosphere

Statistical Study of the Relationship Between Ion Upflow and Field‐Aligned Current in the Topside Ionosphere for Both Hemispheres During Geomagnetic Disturbed and Quiet Time

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Geomagnetic and solar activity dependence of ionospheric upflowing O+: FAST observations

Cited by 6 publications

References 53 publications

Latitude Dependence of Low‐Altitude O+ Ion Upflow: Statistical Results From FAST Observations

Latitude Dependence of Low‐Altitude O+ Ion Upflow: Statistical Results From FAST Observations

Characteristics of the Occurrence of Ion Upflow in Association With Ion/Electron Heating in the Polar Ionosphere

Statistical Study of the Relationship Between Ion Upflow and Field‐Aligned Current in the Topside Ionosphere for Both Hemispheres During Geomagnetic Disturbed and Quiet Time

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Latitude Dependence of Low‐Altitude O⁺ Ion Upflow: Statistical Results From FAST Observations

Latitude Dependence of Low‐Altitude O⁺ Ion Upflow: Statistical Results From FAST Observations