The 4-emission-core structure of dayside aurora oval observed by all-sky imager at 557.7nm in Ny-Ålesund, Svalbard

Hu, Zejun; Yang, Huigen; Liang, Jimin; Han, Desheng; Huang, De‐Hong; Hu, Hongqiao; Zhang, Beichen; Liu, R.; Chen, Z.

doi:10.1016/j.jastp.2010.03.005

Cited by 13 publications

(12 citation statements)

References 40 publications

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“…During the whole winter of 2005, the exposure and readout times of the all-sky cameras were set at 7 and 3 s, respectively. Thus, the time resolution of tahe optical aurora data is 10 s. Based on its superior geomagnetic location in the polar cusp region and multi-wavelength optical imaging instruments, YRS is an ideal auroral observatory for continuously monitoring dayside auroral emissions during the whole winter in the Northern Hemisphere, and can provide plentiful source data for auroral investigations since its initial operation in late 2003 (Hu et al 2009;Hu et al 2010;Zhang et al 2010;Hu et al 2012).…”

Section: Instrumentationmentioning

confidence: 99%

Simultaneous ground-based optical and SuperDARN observations of the shock aurora at MLT noon

Liu

Han

et al. 2015

Earth Planet Sp

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Using ground-based high temporal and spatial optical aurora observations, we investigated one fortuitous event to illustrate the direct responses of the fine structure auroral emission to interplanetary shock on 7 January 2005. During the shock impact to the magnetosphere, the Chinese Arctic Yellow River Station (YRS) equipped with all-sky imagers (ASIs) was situated at the magnetic local noon region (~1210 MLT) in the Northern Hemisphere, while the SuperDARN CUTLASS Finland HF radar covering the field of view (FOV) of the ASIs at YRS had fine ionospheric plasma convection measurement. We observed that an intensified red aurora manifesting as a discrete emission band at a higher latitude responds to the shock impact gradually, which results in a distinct broadening of the dayside auroral oval due to the equatorward shifting of its lower latitude boundary after the shock arrival. In contrast, the green diffuse aurora, manifesting as a relatively uniform luminosity structure, reacts immediately to the shock compression, displaying prompt appearance in the southern edge of the FOV and subsequent poleward propagation of its higher latitude boundary. Simultaneously, the CUTLASS Finland radar monitored enhanced backscatter echo power and increased echo number, which coincided with intensified discrete aurora in approximately the same latitudinal region. Doppler velocity measurement showed moving ionospheric irregularities with generally enhanced line-of-sight (LOS) speed, but with prominent sunward flow in the polar cap and antisunward flow in both the eastern and western regions. The SuperDARN global ionospheric convection pattern clearly presented a large-scale plasma flow divided in four circulation cells, with two reversed flow cells nested in the noon sector of the polar cap. These direct observations strongly suggest that the prompt shock compression intensified the wave-particle interaction in the inner magnetosphere and enhanced the lobe magnetic reconnection rate at magnetospheric high latitude.

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Section: Instrumentationmentioning

confidence: 99%

Simultaneous ground-based optical and SuperDARN observations of the shock aurora at MLT noon

Liu

Han

et al. 2015

Earth Planet Sp

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“…PMAFs are one of the most intensively investigated phenomena in the dayside high-latitude ionosphere, and are commonly interpreted as an ionospheric signature of magnetic reconnection [2][3][4][6][7][8][9][11][12][13][14][15][26][27][28][29][30][31][32][33][34][35] . Both case studies and statistical studies based on long-term auroral observations have shown that the majority of PMAFs occurred during southward IMF, suggesting an association with enhanced low-latitude reconnection on the dayside magnetopause.…”

Section: Discussionmentioning

confidence: 99%

Simultaneous optical and radar observations of poleward moving auroral forms under different IMF conditions

Zou¹,

Yang²,

Han³

et al. 2012

APS

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Using high temporal resolution optical data obtained from three-wavelength all-sky imagers at Chinese Yellow River Station in the Arctic, together with the EISCAT Svalbard radar (ESR) and SuperDARN radars, we investigated the dayside poleward moving auroral forms (PMAFs) and the associated plasma features in the polar ionosphere under different interplanetary magnetic field (IMF) conditions, between 0900 and 1010 UT on 22 December 2003. Simultaneous optical and ESR observations revealed that all PMAFs were clearly associated with pulsed particle precipitations. During northward IMF, particles can precipitate into lower altitudes and reach the ionospheric E-region, and there is a reverse convection cell associated with these PMAFs. This cell is one of the typical signatures of the dayside high-latitude (lobe) reconnection in the polar ionosphere. These results indicate that the PMAFs were associated with the high-latitude reconnection. During southward IMF, the PMAFs show larger latitudinal motion, indicating a longer mean lifetime, and the associated ionospheric features indicate that the PMAFs were generated by the dayside low-latitude reconnection.

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“…[37] In our previous work [Hu et al, 2010], through tracing the geomagnetic field lines of the Tsyganenko-96 model [Tsyganenko and Stern, 1996], we found that the field lines from the region W (H) cross the prenoon (postnoon) highlatitude magnetopause which is the antiparallel reconnection regions (Figure 5a). As pointed out in section 5.1.1, when IMF has a By component, that is, By > 0 (By < 0), the APR occurs at the southern (northern)/prenoon and northern (southern)/postnoon high-latitude magnetopauses, respectively.…”

Section: Auroral Emissions Related To the Cr In The Midday Oval And Amentioning

confidence: 98%

“…The case study [ Hu et al , 2009] and the statistical analysis [ Wang et al , 2010] presented that there are different typical auroral forms in each region. On the basis of the auroral spectral and forms in AARs [ Hu et al , 2009] and the magnetospheric sources of every AAR tracing along the geomagnetic field lines [ Hu et al , 2010], the potential connection that the solar wind–magnetosphere dynamic processes result in these auroral features is illuminated: the auroral emissions in the prenoon “warm spot” and postnoon “hot spot” should be partially related to the dayside reconnection, especially antiparallel reconnection at the prenoon/postnoon high‐latitude magnetopause, while the auroral emissions in the dusk and dawn regions of the dayside oval should be dominantly associated with the KHI at the dusk and dawn flank magnetopause.…”

Section: Introductionmentioning

confidence: 99%

Dayside auroral emissions controlled by IMF: A survey for dayside auroral excitation at 557.7 and 630.0 nm in Ny‐Ålesund, Svalbard

Yang

Han

et al. 2012

J. Geophys. Res.

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.[1] A survey of dayside 557.7 and 630.0 nm auroral emission, acquired from the all-sky imagers at the Yellow River Station in Ny-Ålesund, Svalbard, shows that the dayside auroral oval could be divided into five auroral active regions: the dawnside (Da, 06:00-07:30 MLT) and duskside (Du,(15)(16)(17):00 MLT) green aurora sectors, the prenoon (W, 07:30-10:00 MLT) and postnoon (H, 13:00-15:30 MLT) peaks for 557.7 and 630.0 nm auroral emissions, and the midday gap (M, 10:00-13:00 MLT) for green aurora. The 630.0 nm intensities in W, M, and H nearly increase linearly with the Kan-Lee electric field. The 630.0 nm auroral emissions in W and H show a double-peak feature associated with the change of interplanetary magnetic field (IMF) clock angle: one peak at 90°and the other at 270°. The 630.0 nm emission in M, however, is dominantly excited during the clock angle of 90°-270°. It is considered that the 630.0 nm emissions in W/H and M are related to the prenoon/postnoon antiparallel reconnection at the high-latitude magnetopause and the subsolar component reconnection, respectively. Moreover, the 630.0 nm intensity in the dayside oval shows the monotonic increase with the absolute value of the north-south oriented electric field (Ez), but the increasing rate of the intensity in the postnoon (prenoon) oval is larger than that in the prenoon (postnoon) oval when IMF By is negative (positive). Only the 557.7 nm intensity in region M and H/Du increases gradually with the absolute value of negative Ez. These features should be associated with the change of interhemispheric currents produced by Ez.

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The 4-emission-core structure of dayside aurora oval observed by all-sky imager at 557.7nm in Ny-Ålesund, Svalbard

Cited by 13 publications

References 40 publications

Simultaneous ground-based optical and SuperDARN observations of the shock aurora at MLT noon

Simultaneous ground-based optical and SuperDARN observations of the shock aurora at MLT noon

Simultaneous optical and radar observations of poleward moving auroral forms under different IMF conditions

Dayside auroral emissions controlled by IMF: A survey for dayside auroral excitation at 557.7 and 630.0 nm in Ny‐Ålesund, Svalbard

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