Next PPARC Seminar

        PPARC seminar news #17 in FY2017
2017/11/20 (Mon.) 9:00-12:00 at S407 @ C building  chairperson: Misawa

Fuminori Tsuchiya 土屋史紀
Energetic electron precipitation associated with pulsating aurora observed by VLF/LF radio propagation at Athabasca during Arase ground-based observation campaign
Recent studies of pulsating aurora (PsA) suggest that energetic electrons whose energies are up to several hundred keV also precipitate into the atmosphere associated with PsA and they are caused by pitch angle scattering through wave-particle interaction with whistler mode chorus waves. On the other hand, observation of periodic variations in the energetic electron precipitation with time scale of PsA (several seconds) has not been reported yet.
Here we show clear correlation between time variations in PsA and energetic electron precipitation observed at Athabasca during recovery phase of substorm on 27 Mar. 2017. PsA was observed by one of all sky imagers of THEMIS GBO stations with 3-sec cadence and energetic electron precipitation was detected using sub-ionospheric propagation of VLF/LF radio waves with 0.1-sec time resolution. The sub-ionospheric propagation is sensitive to electron with energy higher than 100keV. The result supports a conclusion that several hundred keV electrons precipitate into the atmosphere associated with PsA.

Mizuki Fukizawa 吹澤瑞貴
Comparing chorus and ECH intensity modulation with time variation of pulsating aurora observed in Iceland
In this study, we report the relationship between time variation of pulsating auroral emission intensity and whistler-mode chorus and ECH waves. Pulsating aurora is a kind of diffuse aurora which is mainly observed during the substorm recovery phase at the post midnight. Pulsating aurora shows two typical time variations. One is the time variation whose period is from a few to a few tens seconds. The other is a few Hz modulation. Pulsating aurora is thought to be generated by precipitating electrons from the magnetosphere into the ionosphere which interact with whistler waves at the magnetic equator. Nishimura et al. [2010] reported that, among whistler waves, especially chorus waves generated by non-linear wave-particle interaction show time variation consistent with that of pulsating aurora by observation with THEMIS satellite and ground-based all-sky imager. However the number of events used for the comparison between modulation of whistler-mode chorus wave and pulsating aurora is limited and thus the cause of pulsating aurora has not been explained completely. ERG satellite was successfully launched in December 2016. And ERG is observing the plasma electric and magnetic field at the pulsating aurora source region. We analyze the data obtained during ERG satellite-ground based simultaneous champagne observation.
On 21 March 2017, the footprint of ERG satellite transited through the field of view of the National institute of Polar Research panchromatic all-sky imager which installed at Husafell, Iceland (geographic latitude: 64.67°N, geographic longitude: 338.97°W, geomagnetic latitude: 69.13°, geomagnetic longitude: 71.67°) during 04:00-06:00 UT (03:40-05:40 MLT). The solar wind data showed that the magnetic field intensity and proton density increased from 5 nT to 18 nT and from 15 cm^(-3) to 50 cm^(-3) respectively during 00 UT to 06 UT . The solar wind speed increased during 07 UT on 21 March to 00 UT on 23 March. These data indicate that the Corotating Interaction Region (CIR) reached the Earth.The time resolution of Watec all-sky imager is about 2 Hz. This all-sky imager recorded aurora images in the mpeg format by digital video recorder (DVR) during this time. The effective pixels are 720 x 240 pixels and the frame rate of DVR is 3 fps. So we created 3 fps images from the movie. The pixels of each image are 639 x 449, 8 bit/pixel. Although this imager is not monochromatic, we assumed that 557.7 nm auroral emission was dominant in images and calculated geographic latitude and geographic longitude of each pixel in images and then, mapped images on geographic coordinate at 110 km altitude.  As a result, elongated arc in the east-west direction moved from high latitude (magnetic latitude 70.5 degrees, geographic latitude 66.5 degrees) to low latitude (magnetic latitude 69.5 degrees, geographic latitude 65.5 degrees) within the field of view of the all-sky imager. And then, pulsating aurora was observed within the range from magnetic latitude 69-72 degrees during 04:40-05:30 UT. At this time, ERG observed plasma waves and particles at the morning side magnetic equator (3.9-4.8 MLT). The distance from the center of the Earth to ERG was L~6 R_E. We compared between lower- and upper-band chorus and Electrostatic cyclotron harmonic (ECH) waves observed by PWE/OFA and time variation of aurora at each pixel in the all sky images. 
The highest cross-correlation coefficient (0.460) between LBC and aurora is located 0.76 ° south and 0.94° west of the IGRF model footprint. On the other hand, The highest cross-correlation coefficient (0.737) between ECH and aurora is located 1.15 ° north and 1.30° east of the IGRF model footprint. Magnetic field observed by ERG/MGF was weaker than  that of IGRF model. This indicate that correct  ERG footprint would locate in the south direction from the footprint derived by IGRF model. The highest cross-correlation coefficient pixel of LBC is consistent with this idea but that of ECH is not consistent. So LBC would correlate with pulsating aurora, but ECH would not correlate with pulsating aurora.

----- PPARC seminar schedule (v1.7, 2017-11-15) ---
17/11/20(Mon) 9:00-12:00 Tsuchiya, Fukizawa (char:Misawa)
17/11/27(Mon) 9:00-12:00 Sakanoi, Koga (char:Tsuchiya)
17/12/04(Mon) cancelled
17/12/11(Mon) 9:00-12:00 Hino, Kagitani (char:Sakanoi)
17/12/18(Mon) 9:00-12:00 Okada, Yoshizawa (char:Kaneda)
17/12/25(Mon) 9:00-12:00 Yagi, Watanabe (chair:Kagitani)
18/01/08(Mon) holiday
18/01/15(Mon) - no seminar-
18/01/16(Tue) B4研究発表会
18/01/19(Fri) D論締切
18/01/22(Mon) - no seminar -
18/01/26(Fri) M論締切
18/01/29(Mon) 9:00-12:00 Kaneda, Mizuguchi
18/01/30(Tue) 9:00-12:00 Arakawa, Endo
18/01/31(Wed) 13:00-16:00 Koizumi, Mimura
18/02/05-02/08 D/M審査会
18/02/12(Mon) holiday
18/02/15(Thu)  13:00-16:00 Watanabe, Fukizawa (review)
18/02/19(Mon) 9:00-12:00 Hirai, Ishikawa (review)
18/02/27-3/1 惑星圏研究会
----- 発表者 -----
D/1回: Mizuguchi, Kaneda, Kodama
M2/1回: Endo, Koizumi, Arakawa, Mimura
M1/2回: Ishikawa, Hirai, Fukizawa, Watanabe, うち1回はreview
B4/2回: Yoshizawa, Hino, Okada, Yagi

----- C-group seminar schedule (v1.4, 2017-09-26) ---
17/09/25(Mon)  13:00-17:30 D thesis preliminary oral exam. (Kaneda, K. Endo)
17/09/28(Thu)  13:00-16:30 M thesis preliminary oral exam. (Mimura, Y. Endo)
17/10/05(Thu)  09:00-16:00 SGEPSS reherasal
17/10/12(Thu)  13:00-16:30 M thesis preliminary oral exam. (Nishida, Terada)
17/10/15-19    (SGEPSS in Kyoto)
17/10/26(Thu)  13:00-16:30 M thesis preliminary oral exam. (Koizumi, Arakawa)
17/11/02(Thu)  13:00-16:30 M thesis preliminary oral exam. (Ishigaya, Kamada)
17/11/09(Thu)  (Geophys. Joint Seminar)
17/11/16(Thu)  13:00-   D2 interim report (Ooki)
17/11/23(Thu)  (holiday)
18/02/22(Thu)  13:00-   D2 interim report (Aizawa)


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  • C-Group - Seminar

    **  C-Group Seminar News '17 No.7  **

      ** Poster #4, and D-Report #4 **

        ** Poster #4 **

    Date & Time : Starting at 13:00 on Thursday, June 22
    Place : Lecture Room #N404

    T. Akiba

    A. Kamada

    Y. Koizumi
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    K. Mimura
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        ** D-Report #4 **

    Date & Time : Starting at 14:40 on Thursday, June 22
    Place : Lecture Room #N404

    K. Arao
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    *** C-group seminar 2017 schedule (v1.4, 2017-03-31) ***
    17/06/22(Thu) 13:00- Poster#4(Akiba, Kamada, Koizumi, Mimura), D-presen (Arao)
    17/06/29(Thu) 13:00- D-presen (K.Endo, Mizuguchi)
    17/07/13(Thu) Guest speaker (Prof.Tanaka from astronomical Institute)
    #May-June Bepi-SWT
    #Aug 20-31 IAU
    Poster presen: M1, M2 & D3
    D-presen: Mizuguchi, Koga

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