PPARC seminar news #04 in FY2017
2017/4/27(Thu) 13:00-16:00 at S407 @ C building chairperson: Koga
Haruna Watanabe (M1) 渡辺 はるな
"UV and IR auroral emission model for the outer planets: Jupiter and Saturn comparison" (review)
Chihiro Tao, S.V. Badman, M. Fujimoto, 2011. Icarus 213, 581-592, doi:10.1016/j.icarus.2011.04.
The outer planetary aurora are most often observed in the ultraviolet (UV) and the infrared (IR) wavelengths.
How the emissions in these different wavelengths are connected with the background physical conditions are not
yet well understood. They develop a model which estimates UV and IR emission rates accounting for UV
absorption by hydrocarbons, ion chemistry, and H3+ non-LTE effects.
The dependences of UV and IR emissions on electron flux are found to be similar at Jupiter and Saturn.
However, the dependences of the emissions on electron energy are different at the two planets,
especially for low energy (<10 keV) electrons; the UV and IR emissions both decrease with decreasing
electron energy, but this effect in the IR is less at Saturn than at Jupiter. The temperature sensitivity of the
IR emission is also greater at Saturn than at Jupiter. These dependences are interpreted as results of non-
LTE effects on the atmospheric temperature and density profiles. The different dependences of the UV and
IR emissions on temperature and electron energy at Saturn may explain the different appearance of polar
emissions observed at UV and IR wavelengths, and the differences from those observed at Jupiter.
I will talk about their estimation of the conditions for such IR-only emissions to appear.
Asuka Hirai(M1) 平井 あすか
EMIC waves-driven radiation belt electron precipitation into the atmosphere with ground-based observations in the subauroral region
Energetic electron losses from the outer radiation belt occur during magnetic storm and substorm. One of the mechanisms is precipitation into the atmosphere and electromagnetic ion cyclotron (EMIC) waves are one of candidates to cause pitch angle scattering of energetic electron. EMIC waves ,which are observed in the Pc1-Pc2 frequency range (0.1-5Hz) are excited by the ion cyclotron instability in the equatorial region of the magnetosphere during the main and the recovery phase of magnetic storms. It has been theoretically studied that EMIC waves play an important role in energetic electron precipitation into the atmosphere, but there have been limited experimental observations to support this idea.
Here, we investigated relation between occurrence of EMIC waves and energetic electron precipitation by means of ground-based magnetometers and low frequency (LF) radio wave propagation observation and confirmed EMIC waves to be driving electron precipitation.
We detected energetic electron precipitation from the LF radio wave observation in 07:00-09:20 UT on July 7, 2011 and EMIC waves were observed by the induction magnetometer at Athabasca in 05:35-10:55 UT on the same day.
In this seminar, I will talk about the result of that event analysis.
*** PPARC seminar schedule (v1.4, 2017-03-31) ***
Date, start time, presenters, (chairperson)
17/04/06(Thu) 13:00- Obara, Sakanoi (Kagitani)
17/04/10(Mon) 09:00- Mizuguchi (Obara)
17/04/17(Mon) 09:00- Fukizawa, Ishikawa (Mizuguchi)
17/04/27(Thu) 13:00- Watanabe, Hirai (Koga)
17/05/12(Fri) 13:00- Obara, Misawa (Kaneda)
17/05/29(Mon) 09:00- presentations of B4-experiments (4) (Tsuchiya)
17/06/05(Mon) 09:00- Endo, Tsuchiya (Kagitani)
17/06/12(Mon) 09:00- Arakawa, Sakanoi (Obara)
17/06/12-16 MOP conference
17/06/15(Thu) 13:00- Mimura, Koizumi (Mizuguchi)
17/06/19(Mon) 09:00- Okada, Hino (Kaneda)
17/07/06(Thu) 13:00- Yagi, Yoshizawa (Misawa)
17/07/13(Thu) 13:00-> C-seminar
17/07/14(Fri) 13:00- Kaneda (Misawa)
17/07/21(Fri) 13:00- Koga, Kagitani (Tsuchiya)
** C-Group Seminar News '17 No.2 **
** Topics & Lecture **
Date & Time : Starting at 13:00 on Thursday, April 13
Place : Lecture Room #N404
** Topics **
Title: Brief review of ELF/VLF emissions at subauroral latitudes: ground and space observations
Presenter: Claudia MARTINEZ
Abstract: Since 2012, continuous measurements of ELF/VLF emissions, have been carried out using a 100-kHz sampling loop antenna at Athabasca (ATH), Canada (54.60N, 246.36E, L=4.3). We used this data to investigate: (1) spectral and polarization characteristics of these waves (2) location of the ionospheric exit point of chorus emissions (3) first statistical analysis of all ELF/VLF emissions observed on the ground at subauroral latitudes (including features, occurrence and association with solar wind parameters). We found maximum occurrence in the morning (06-07 MLT) sector and positive correlation between ongoing substorm/storm activities with increase of wave occurrence.
In addition, we use conjugate/simultaneous events between RBSP and ATH (same spectral and frequency features) to study wave propagation and generation: (1) QP emission with accompanying short pulse (<1 sec) in the dawn sector (04-06 MLT). We use ray tracing based on plasmaspheric density observed by the spacecraft to validate a propagation scenario. (2) Discrete burst lasting ~3 min at 11:17 UT (03 MLT) associated with strong magnetospheric compression (SI with SYM-H amplitude ~63 nT at ATH). At RBSP-B we also observed a hiss emission starting earlier that was not observed by ATH. We discuss the differences in generation mechanisms and propagation for these two emissions.
** Lecture **
Title: Expectations for Arase (ERG) satellite observation toward further investigation of wave-particle interactions in planetary magnetospheres
Presenter: Yuto KATOH
Abstract: The Arase satellite was launched at 20 December 2016 for the exploration of energization and radiation in geospace. One of the prime targets of the Arase satellite is the formation process of radiation belts in the Earth's inner magnetosphere, in which wave-particle interactions between whistler-mode chorus emissions and relativistic electrons play critical roles. Since whistler-mode chorus have been commonly observed in planetary magnetospheres of our solar system, results of investigation by Arase should contribute thorough understanding of wave-particle interactions occurring around other magnetized plantes. In this Lecture we review interactions in the inner magnetosphere mostly focusing on whistler-mode chorus emissions and discuss expectations for the Arase satellite observation.
*** C-group seminar 2017 schedule (v1.4, 2017-03-31) ***
17/04/13(Thu) 13:00- Lecture(Kato)
17/04/20(Thu) 13:00- Poster#1(Fukizawa, Ishikawa, Ishigaya), D-presen(Ohki)
17/05/11(Thu) 9:00-17:00 JpGU Rehearsal
17/06/01(Thu) 13:00- Poster#2(Kaneda, Arakawa, Watanabe, Dai, Takenaka, Toyooka), D-presen (Koga)
17/06/08(Thu) 13:00- Poster#3(Y.Endo, Hirai, Nishida, K.Terada), D-presen
17/06/12-16 MOP conference
17/06/22(Thu) 13:00- Poster#4(Akiba, Kamada, Koizumi, Mimura), D-presen
17/06/29(Thu) 13:00- D-presen (K.Endo, Mizuguchi)
17/07/13(Thu) Guest speaker (Prof.Tanaka from astronomical Institute)
#Aug 20-31 IAU
Poster presen: M1, M2 & D3
D-presen: Mizuguchi, Koga
Evolution and propagation of electric fields during magnetospheric disturbances based on multiple spacecraft and ground-based observations
Feasibility of the future observations by mid-infrared heterodyne spectroscopy for Wind and Temperature in Venusian mesosphere and lower thermosphere