Poleward moving auroral forms (PMAFs) observed at the Yellow River Station: A statistical study of its dependence on the solar wind conditions

Zou, Xing; Yang, Huigen; Han, Desheng; Wu, Zhensen; Hu, Zejun; Zhang, Q.H.; Kamide, Y.; Hu, Hongqiao; Zhang, B.C.; Liu, J.M.; Huang, De‐Hong

doi:10.1016/j.jastp.2012.06.004

Cited by 34 publications

(44 citation statements)

References 34 publications

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“…Besides the different clock angle preferences discussed above, it is also noteworthy that the clock angle distribution of the sum of two categories resemble that of dayside PMAFs found by Xing et al . [], consistent with PMAFs and associated flows being the source of airglow patches and their commonly associated polar cap flow enhancements.…”

Section: Statisticssupporting

confidence: 73%

“…In contrast, when localized flows were not identified over patches, the preferential IMF condition was − B z ‐dominated, indicating that the patches were being carried by large‐scale convection. The sum of the two distributions resembles the clock angle dependence of dayside PMAFs [ Xing et al ., ], suggesting that PMAFs, as well as the associated fast flow bursts, may be the source of localized flow enhancements in the polar cap. Also, our flows' preference to ± B y may be related to the different PMAF behaviors that have been observed as a function of IMF clock angles.…”

Section: Discussionmentioning

confidence: 99%

“…Comparing these B x , B y , and B z dependences to those of dayside PMAFs reveals interesting similarities. For example, PMAFs show a bimodal dependence on B x with higher occurrence on − B x [ Xing et al ., ]. PMAFs also show an asymmetry in B y dependence, biased to + B y for northern hemisphere PMAFs [ Fasel , ; Xing et al ., ] and − B y for southern hemisphere ones [ Drury et al ., ].…”

Section: Statisticsmentioning

confidence: 99%

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Localized polar cap flow enhancement tracing using airglow patches: Statistical properties, IMF dependence, and contribution to polar cap convection

et al. 2015

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Recent radar observations have suggested that polar cap flows are highly structured and that localized flow enhancements can lead to nightside auroral disturbances. However, knowledge of these flows is limited to available echo regions. Utilizing wide spatial coverage by an all-sky imager at Resolute Bay and simultaneous Super Dual Auroral Radar Network measurements, we statistically determined properties of such flows and their interplanetary magnetic field (IMF) dependence. We found that narrow flow enhancements are well collocated with airglow patches with substantially larger velocities (≥200 m/s) than the weak large-scale background flows. The flow azimuthal widths are similar to the patch widths. During the evolution across the polar cap, the flow directions and speeds are consistent with the patch propagation directions and speeds. These correspondences indicate that patches can optically trace localized flow enhancements reflecting the flow width, speed, and direction. Such associations were found common (~67%) in statistics, and the typical flow speed, propagation time, and width within our observation areas are 600 m/s, tens of minutes, and 200-300 km, respectively. By examining IMF dependence of the occurrence and properties of these flows, we found that they tend to be observed under B y -dominated IMF. Flow speeds are large under oscillating IMF clock angles. Localized flow enhancements are usually observed as a channel elongated in the noon-midnight meridian and directed toward premidnight (postmidnight) for +B y (ÀB y ). The potential drops across localized flow enhancements account for~10-40% of the cross polar cap potential, indicating that they significantly contribute to polar cap plasma transport.

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Section: Statisticssupporting

confidence: 73%

Section: Discussionmentioning

confidence: 99%

Section: Statisticsmentioning

confidence: 99%

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Localized polar cap flow enhancement tracing using airglow patches: Statistical properties, IMF dependence, and contribution to polar cap convection

et al. 2015

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“…These are all comparable with the observational properties of throat aurora, because throat auroras often contain poleward moving aurora forms (PMAFs) (Chen et al, ; Han et al, ). PMAFs have been generally accepted as the ground signature of FTE (Moen et al, ) and have tendency to occur under southward IMF (Xing et al, ), whereas throat aurora show little tendency to occur during southward IMF (Han, Hietala, et al, ). All of these results provide strong evidence that throat auroras are definite ground signatures for the magnetopause transients that are all correspondent to magnetopause indentations.…”

Section: Discussionmentioning

confidence: 99%

Direct Evidence for Throat Aurora Being the Ionospheric Signature of Magnetopause Transient and Reflecting Localized Magnetopause Indentations

et al. 2018

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Magnetopause transients, observing as brief entries into the magnetosheath by satellites, are commonly observed in the vicinity of the magnetopause and have been explained by several possible mechanisms. However, satellite observations alone are insufficient to determine the dynamics and context of transients. Throat auroras are characterized as north‐south aligned discrete auroral forms extending from the equatorward edge of the discrete auroral oval that are only observed near dayside convection throat region and have been suggested as the ionospheric signature of localized magnetopause indentations. Using coordinated observations from the Magnetospheric Multiscale Mission (MMS) and ground‐based all‐sky imagers, we show apparent one‐to‐one correspondences between transients observed by MMS near the subsolar magnetopause and throat auroras observed on the ground. The correspondence is valid not only for typical throat aurora with larger spatial scale but also for these with tiny scales. We even notice that the transient durations observed by satellite are approximately proportional to the width (east‐west extension) of the throat aurora. These results provide direct evidence that throat auroras are ground signatures for the magnetopause transients. With the aid of auroral observations, we suggest that these transients reflect localized magnetopause indentations but are not produced by motion of the entire magnetopause. We also found that most transients observed here are associated with earthward flow enhancements, which indicates that high‐speed jets in the magnetosheath could be a driver for producing these transients.

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“…The dayside Joule heating estimates shown in McHarg et al () are higher for positive B y . Xing et al () showed a tendency for higher occurrence of poleward moving auroral forms for B y positive. All of these reports align with the idea put forth by Saunders () that upward field‐aligned currents (FACs) dominate in the northern hemisphere cusp during positive B y conditions.…”

Section: Resultsmentioning

confidence: 98%

Poynting Flux in the Dayside Polar Cap Boundary Regions From DMSP F15 Satellite Measurements

Deng

Sheng

et al. 2018

JGR Space Physics

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Poynting flux, which describes electromagnetic energy flux, is an important energy source for the high‐latitude upper atmosphere. After the launch of Defense Meteorological Satellite Program (DMSP) F15 spacecraft with a boom‐mounted magnetometer on board, there was a new opportunity to calculate Earth‐directed Poynting flux at satellite altitudes (~850 km) in the upper atmosphere. A persistent enhancement of thermospheric density in the dayside polar cap boundary regions has been reported in the CHAMP satellite observations. To understand the significance of different physical mechanisms including Poynting flux and particle precipitation, and the correlation between them, a statistical study of Poytning flux and particle energy flux in the dayside cusp and low‐latitude boundary layer (LLBL) regions has been conducted based on DMSP F15 measurements. DMSP satellite observations showed a dominate downward Poynting flux for most cases in the cusp region. Our analysis of DMSP F15 data for five years (2000–2004) reveals that approximately 53% of 660 cusp crossings at 800–850 km showed strong downward Poynting flux (S > 10 mW/m2), 32% of the crossings had noticeable downward Poynting flux (S > 3 mW/m2), and 7% of the crossings did not show clear Poynting flux (S < 1 mW/m2). Only 13 out of 660 cusp crossings (~2%) showed noticeable upward Poynting flux. In the LLBL region, 35% of 11,641 LLBL crossings showed significant downward Poynting flux, 34% of the crossings had noticeable downward Poynting flux, and only 13% of the crossings did not show clear Poynting flux. On average, Poynting flux in LLBL is smaller than that in the cusp. The results show a slightly negative correlation between Poynting flux and particle precipitation energy flux in the dayside polar cap boundary regions. Statistically, Poynting flux in the cusp is enhanced during interplanetary magnetic field By positive conditions.

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Poleward moving auroral forms (PMAFs) observed at the Yellow River Station: A statistical study of its dependence on the solar wind conditions

Cited by 34 publications

References 34 publications

Localized polar cap flow enhancement tracing using airglow patches: Statistical properties, IMF dependence, and contribution to polar cap convection

Localized polar cap flow enhancement tracing using airglow patches: Statistical properties, IMF dependence, and contribution to polar cap convection

Direct Evidence for Throat Aurora Being the Ionospheric Signature of Magnetopause Transient and Reflecting Localized Magnetopause Indentations

Poynting Flux in the Dayside Polar Cap Boundary Regions From DMSP F15 Satellite Measurements

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