Double bursts inside a poleward‐moving auroral form in the cusp

Taguchi, S.; Hosokawa, K.; Ogawa, Y.; Aoki, Takao; Taguchi, Makoto

doi:10.1029/2012ja018150

Cited by 23 publications

(38 citation statements)

References 29 publications

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“…Its motion generally has a poleward component and very often also has a strong azimuthal component. As has been shown by many researchers (e.g., Sandholt et al 1986;Lockwood et al 1989;Fasel 1995;Sandholt and Farrugia 2003;Oksavik et al 2004;Taguchi et al 2012), the azimuthal motion is eastward or westward, which is consistent with the direction of the interplanetary magnetic field (IMF) B Y -related tension force arising from the curvature of the open magnetic field line after reconnection on the dayside magnetopause.…”

Section: Introductionsupporting

confidence: 51%

“…The all-sky imager uses an electron multiplier charge-coupled device (EMCCD) camera (Hamamatsu, C9100-13, Hamamatsu, Japan) with an imaging resolution of 512 × 512 pixels and measures emission at two wavelengths, 557.7 and 630.0 nm, using narrow passband interference filters. This ground-based imager has been operating in Longyearbyen, Norway, (geographical latitude 78.1°N and longitude 16.0°E) since October 2011 (Taguchi et al 2012). As shown in Taguchi et al (2012), the 630.0 nm (red) line data from this EMCCD camera can provide detailed information about the dynamic features of moving cusp auroral structures.…”

Section: Instrumentationmentioning

confidence: 99%

“…This ground-based imager has been operating in Longyearbyen, Norway, (geographical latitude 78.1°N and longitude 16.0°E) since October 2011 (Taguchi et al 2012). As shown in Taguchi et al (2012), the 630.0 nm (red) line data from this EMCCD camera can provide detailed information about the dynamic features of moving cusp auroral structures. The high sensitivity of this camera is also very effective for identifying the structure of polar cap patches (Hosokawa et al 2013a(Hosokawa et al , 2013bSakai et al 2014).…”

Section: Instrumentationmentioning

confidence: 99%

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Investigating the particle precipitation of a moving cusp aurora using simultaneous observations from the ground and space

Taguchi

Hosokawa

Ogawa

2015

Prog. in Earth and Planet. Sci.

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Using observations of a moving cusp aurora from a high-sensitivity all-sky imager at Longyearbyen, Svalbard, and in situ observations of the precipitating particles from a spacecraft that flew over the aurora, we examined the particle precipitation features in the early and final stages of the moving cusp aurora. We focused on two auroral structures created near noon, separated by approximately 3 min, during a southwestward interplanetary magnetic field (IMF) condition on 17 December 2012. The second auroral structure occurred when the IMF turned further southward. Immediately after the appearance of the latter structure, the two auroral structures were adjacently situated, and the DMSP F18 spacecraft passed through these regions. A detailed comparison of the data from particle spectrometers onboard the spacecraft and the 630 nm aurora image data demonstrates that the ion precipitation in the young cusp aurora (i.e., second auroral structure) had a high energy flux, whereas that in the old cusp aurora (i.e., first auroral structure) had a very low energy flux. For the electron precipitation, the features in both regions were found to be very similar; the energy flux at approximately 100 eV often exceeded 1 × 10 9 eV cm −2 s −1 sr −1 eV −1 in both regions. This indicates that the electron precipitation in the moving cusp aurora is maintained at a high flux level over a certain interval from its starting time. Thus, we suggest that the electron precipitation flux in the moving cusp aurora is controlled by a mechanism independent of the ion precipitation.

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Section: Introductionsupporting

confidence: 51%

Section: Instrumentationmentioning

confidence: 99%

Section: Instrumentationmentioning

confidence: 99%

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Investigating the particle precipitation of a moving cusp aurora using simultaneous observations from the ground and space

Taguchi

Hosokawa

Ogawa

2015

Prog. in Earth and Planet. Sci.

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“…A highly sensitive all‐sky airglow imager (ASI), located at Longyearbyen (78.2°N, 15.6°E), Svalbard, has been operational since October 2011 [ Taguchi et al , ]. The imaging device on the ASI, which is equipped with an electron multiplying charge coupled device (EMCCD) camera (Hamamatsu, C9100‐13), has 512×512 pixels.…”

Section: Instrumentation and Model Descriptionmentioning

confidence: 99%

Storm time enhancements of 630.0 nm airglow associated with polar cap patches

et al. 2014

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We examined the brightness of 630.0 nm airglow, I630, associated with polar cap patches observed during a magnetic storm that occurred on 22 January 2012. Brightness was measured using an all‐sky imager (ASI) located at Longyearbyen, Svalbard. The observed I630 was compared with the F region electron density observed by the European Incoherent Scatter Svalbard Radar (ESR). The I630 was positively correlated with the F2 layer peak electron density, NmF2, and inversely correlated with the altitude of the F2layer peak electron density, hmF2, as expected from the known relationship between these parameters. To estimate the altitude of the peak emission of the airglow, we performed model calculations of the volume emission rate, V630, under quiet and disturbed conditions, using Mass Spectrometer Incoherent Scatter modeled neutral gas profiles and the electron density profile obtained from the ESR data. In order to validate the V630 calculation, I630 was calculated by integrating the V630 along altitude and then compared with the ASI‐observed I630. During the observation periods the measured brightness frequently exceeded the calculated I630; we infer that in most cases, low‐energy particle precipitation is responsible for the extra brightness. However, when there was less particle precipitation, the observed values were in good agreement with the calculated values. Under the magnetically disturbed conditions during our observations, the model calculation showed that the altitude of V630 peak increases, the thickness of the emission layer increases, and patch brightness increases.

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“…In order to directly visualize the structuring process of patches, we deployed a highly sensitive all‐sky airglow imager (ASI) in Longyearbyen, Norway (78.1°N, 15.5°E, Altitude Adjusted Corrected Geomagnetic Coordinates latitude 75.3°) in October 2011 [ Taguchi et al , ]. The ASI uses an electron multiplier charge‐coupled device (EMCCD) camera (Hamamatsu, C9100‐13) in its imaging part, which has 512×512 pixels spatial resolution.…”

Section: Introductionmentioning

confidence: 99%

Two‐dimensional direct imaging of structuring of polar cap patches

et al. 2013

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[1] A highly sensitive all-sky electron multiplier charge-coupled device airglow imager has been operative in Longyearbyen, Norway (78.1 ı N, 15.5 ı E), since October 2011. The imager obtains the 630.0 nm all-sky images with an exposure time of 4 s, which is about 10 times shorter than the conventional cooled CCD airglow imagers. This new equipment allows us to image the ongoing structuring of polar cap patches in 2-D fashion. Here we report a case in which faint undulations appeared along the trailing edge of patches propagating in the central polar cap. The separation between the fingers in the undulations was about 50-100 km and the e-folding time of their growth was 5 min. We suggest that the gradient-drift instability (GDI) is one of the possible generation mechanisms of the undulating structures. The reasons for this interpretation are (1) the asymmetry in the preference of structuring between the leading and trailing edges is qualitatively consistent with the GDI mechanism and (2) the linear growth rate of GDI calculated by using electron density estimates from simultaneous European Incoherent Scatter Svalbard radar observations is roughly consistent with the observed growth time of the fingers. Such "unstable polar cap patches" could be important sources of seed irregularities, which would eventually be broken down to smaller-scale density perturbations affecting the transionospheric satellite communications in the central polar cap.

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Double bursts inside a poleward‐moving auroral form in the cusp

Cited by 23 publications

References 29 publications

Investigating the particle precipitation of a moving cusp aurora using simultaneous observations from the ground and space

Investigating the particle precipitation of a moving cusp aurora using simultaneous observations from the ground and space

Storm time enhancements of 630.0 nm airglow associated with polar cap patches

Two‐dimensional direct imaging of structuring of polar cap patches

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