PEM09-P01

会場:コンベンションホール

時間:5 月 27 日 18:15-19:30

The properties of ionosphere during extreme low solar activity over the equatorial ionization anomaly crest area
The properties of ionosphere during extreme low solar activity over the equatorial ionization anomaly crest area
CHUO, Yu-jung1∗
CHUO, Yu-jung1∗
11

Department of Information Technology, Ling Tung University
Department of Information Technology, Ling Tung University

The solar activity during 2008-2009 is extremely unusually long lower, which offers us an opportunity to study the properties
of ionosphere over the equatorial ionization anomaly crest area. This study collected ionospheric data from ground-based observation of Chung-Li and GPS data of TWTF receiver during 2008-2009. In this investigation, we show the seasonal, monthly,and daily variations during the prolonged low solar activity. Meanwhile, the result also compared with the ionospheric properties
during high solar activity period. Furthermore, a comprehensive discussion of the physics processes for the variation of ionosphere during the prolonged low solar activity period.
キーワード: ionosphere, EIA, ionospheric dynamics, ionospheric physics
Keywords: ionosphere, EIA, ionospheric dynamics, ionospheric physics

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PEM09-P02

会場:コンベンションホール

時間:5 月 27 日 18:15-19:30

Advanced Ionospheric Probe onboard the FORMOSAT-5 Satellite
Advanced Ionospheric Probe onboard the FORMOSAT-5 Satellite
CHAO, Chi-kuang1∗ ; CHANG, Yeou-shin2 ; MINAMI, Shigeyuki3
CHAO, Chi-kuang1∗ ; CHANG, Yeou-shin2 ; MINAMI, Shigeyuki3
1
1

Grad. Inst. of Space Science, National Central Univ., 2 National Space Organization, 3 Osaka City University
Grad. Inst. of Space Science, National Central Univ., 2 National Space Organization, 3 Osaka City University

Advanced Ionospheric Probe (AIP) designed by National Central University is recently accepted by National Space Organization to built for the FORMOSAT-5 (FS-5) satellite as a piggyback science payload in early 2012. The FS-5 satellite isscheduled to launch in 2016 and anticipated to flight in a 98.28o inclination sun-synchronous circular orbit at 720 km altitude in
the 1030/2230 LT sectors. The orbital coverage provides a great opportunity to survey the Earth globally from equatorial to polar
region. The AIP is an all-in-one plasma sensor under constraints in power (5 W), weight (5 kg), and form factor (100 mm L x
100 mm W x 100 mm H) in sensor size but with sampling rate up to 8,192 Hz to measure ionospheric plasma concentrations,velocities, and temperatures over a wide range of spatial scales. Once comprehensive dataset available from the AIP, a systematic
examination of longitudinal and seasonal variations of the ionospheric parameters in the topside F region can be conducted for
all latitudinal coverage. The transient and long-term variations of ionospheric plasma can be monitored in the upcoming solar
maximum period and are benefit to public and scientists who are interested in space weather and seismic precursors associatedwith strong earthquakes.
キーワード: Science payload, Ionosphere, FORMOSAT-5, Advanced Ionospheric Probe
Keywords: Science payload, Ionosphere, FORMOSAT-5, Advanced Ionospheric Probe

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PEM09-P03

会場:コンベンションホール

時間:5 月 27 日 18:15-19:30

Observation and IRI-2012 comparison of F1-layer parameters at the geomagnetic equator
during solar minimum
Observation and IRI-2012 comparison of F1-layer parameters at the geomagnetic equator
during solar minimum
LEE, Chien-chih1∗
LEE, Chien-chih1∗11General Education Center, Chien Hsin University of Science and Technology
General Education Center, Chien Hsin University of Science and Technology

This study is to assess the predictability of IRI-2012 on the equatorial F1 layer during solar minimum. The observed characteristics of F1 layer by the Jicamarca digisonde are compared with the model outputs. The results show that the time range forF1-layer appearance of observation is longer than that of IRI-2012, by at least 1 hour in the early morning and later afternoon.
In IRI-2012, there are three options for the occurrence probability of F1 layer: IRI-95, Scotto-97 no L, and Scotto-97 with L
options. The first option predicts the probability well, but the last two underestimate the probability. The peak density of F1
layer (NmF1) of observation is very close to that of IRI-2012. For the F1 peak height (hmF1), the modeled values are smaller
than the observed ones. The observed seasonal variation of hmF1 is not found in the modeled results. Nevertheless, the observed
diurnal variation of hmF1 is similar to the modeled results with the B0 choices of Bil-2000 and ABT-2009. Regarding the shapeparameter, the values of D1 (the shape parameter of F1 layer in observation) are much greater than the values of C1 (the shapeparameter of F1 layer in IRI-2012). The D1 values are 3-6 time of the C1 values. The diurnal variation of D1 is similar to that of
C1, but the seasonal variation of D1 is not.
キーワード: F1-layer, IRI-2012
Keywords: F1-layer, IRI-2012

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PEM09-P04

会場:コンベンションホール

時間:5 月 27 日 18:15-19:30

Numerical simulation on electrodynamics of the pre-earthquake ionospheric anomalies
Numerical simulation on electrodynamics of the pre-earthquake ionospheric anomalies
LIAN, Chuan-ping1∗ ; LIN, Charles1
LIAN, Chuan-ping1∗ ; LIN, Charles1
1
1

Institute of Earth Sciences, College of Sciences, National Cheng Kung University
Institute of Earth Sciences, College of Sciences, National Cheng Kung University

Over the last few decades, ionospheric observations indicate that the total electron content (TEC) often significantly decreases
in afternoon on 3-5 days before the M>6.0 earthquakes. It is generally considered that electric currents driven by stressedrock flow into ionosphere. We use NRL 3D ionosphere model, SAMI3 to simulate this phenomenon, and add external current
terms into current continuity equation. The range of external current distribution is 120±20oE, 30±20oN, 85˜170km, and the
maximum current density is 500nA/m2. Our simulation result indicates that the upward current on the bottom of ionosphere
produces the maximum (minimum) variation of increasing (decreasing) ˜30% (˜10%) 4TEC. The increasing 4TEC is mainly
located in west region of external current; however, the decreasing 4TEC is mainly located on both sides of increasing region.
キーワード: earthquake precursor, ionospheric dynamics, total electron content
Keywords: earthquake precursor, ionospheric dynamics, total electron content

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PEM09-P05

会場:コンベンションホール

時間:5 月 27 日 18:15-19:30

グローバル MHD モデルで再現される「2 null - 2 separator」磁気圏におけるリコネ
クション電場
Reconnection electric fields in the ”2 null - 2 separator” magnetosphere simulated by aglobal magnetohydrodynamic model渡辺 正和 1∗ ; 藤田 茂 2 ; 田中 高史 1
WATANABE, Masakazu1∗ ; FUJITA, Shigeru2 ; TANAKA, Takashi1
1
1

九州大学, 2 気象大学校
Kyushu University, 2 Meteorological College

It is known that the magnetic reconnection rate is proportional to the field-aligned electric field along the so-called X line. It
represents the rate of the magnetic field vanishing in the diffusion region. In global magnetohydrodynamic (MHD) modelingof the magnetosphere, the field-aligned electric field can be used to identify the reconnection mode occurring in the simulated
magnetosphere. This is particularly useful when antiparallel field line geometry are not formed. One example is the magnetosphere for northward interplanetary magnetic field (IMF). Global MHD simulations generally reproduces the magnetosphericstructure characterized by two magnetic nulls and two separators (which we call here the ”2 null - 2 separator” structure, or ”nullseparator” structure for short). In this configuration, antiparallel magnetic fields do not exist. In addition, the field line geometry
for northward IMF is often too complicated to grasp intuitively. In this study, in order to identify the reconnection mode clearly,
we explicitly calculate the reconnection electric fields in the simulated magnetosphere during northward IMF periods. We apply
this approach to the modeling of the interchange cycle proposed by Watanabe and Sofko [2009, doi:10.1029/2008JA013426].
Although Watanabe et al. [2010, doi:10.1029/2009JA015041] reported observations showing ionospheric signatures of the interchange cycle, there seem to be some debates on the interpretation of the observational data. We aim to support Watanabe etal. [2010] from the modeling point of view. We also discuss the partial collapse of the null-separator structure when the IMF
clock angle (measured from due north) is around 45 degrees. In this case, unconnected IMF lines tangle in the closed field lines
on the nightside, showing a collapse of the null-separator structure. We argue how such a topology is created by analyzing thefield-aligned electric field on separatrices.

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PEM09-P06

会場:コンベンションホール

時間:5 月 27 日 18:15-19:30

Features of long period geomagnetic pulsations caused by the inclined front of the solar
wind discontinuity
Features of long period geomagnetic pulsations caused by the inclined front of the solar
wind discontinuity
KLIBANOVA, Yulia2 ; MISHIN, Vladimir2 ; TSEGMED, B.3 ; MOISEEV, Aleksei4∗
KLIBANOVA, Yulia2 ; MISHIN, Vladimir2 ; TSEGMED, B.3 ; MOISEEV, Aleksei4∗
1

A.A. Ezhevsky Irkutsk State Agrarian University, Irkutsk, Russia, 2 Institute of Solar-Terrestrial Physics Siberian Branch RAS,
Irkutsk, Russia, 3 Research Center for Astronomy and Geophysics, Academy of Sciences of Mongolia, Ulan Bator, 4 Yu.G. Shafer
Institute of Cosmophysical Research and Aeronomy, SB RAS, Yakutsk, Russia
1
A.A. Ezhevsky Irkutsk State Agrarian University, Irkutsk, Russia, 2 Institute of Solar-Terrestrial Physics Siberian Branch RAS,
Irkutsk, Russia, 3 Research Center for Astronomy and Geophysics, Academy of Sciences of Mongolia, Ulan Bator, 4 Yu.G. Shafer
Institute of Cosmophysical Research and Aeronomy, SB RAS, Yakutsk, Russia
We study long-period geomagnetic pulsations caused by the solar wind discontinuity impact during the July 14, 2012 magnetic
storm onset from data of satellite observations in the solar wind and magnetosphere, as well as of ground stations located at low,
middle and high latitudes. The character of pulsations propagation is shown to correspond to their excitation mechanism by
the discontinuity front at the magnetopause. Location relative to the noon of the sector, from which the waves propagate toboth magnetosphere flanks, is determined by the front azimuthal angle inclination. We discuss a change of polarization both bylongitude and latitude directions. The frequency of spectral maximum of the pulsations does not coincide with one of the solar
wind oscillations.
キーワード: geomagnetic pulsations, ULF waves, solar wind discontinuity, wave propagation
Keywords: geomagnetic pulsations, ULF waves, solar wind discontinuity, wave propagation

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PEM09-P07

会場:コンベンションホール

時間:5 月 27 日 18:15-19:30

地上‐衛星同時観測による磁気インパルスに伴う電場の発達・伝播過程
Evolution and propagation of electric fields during magnetic impulses based on multiple
observations
高橋 直子 1∗ ; 笠羽 康正 1 ; 新堀 淳樹 2 ; 西村 幸敏 3 ; 菊池 崇 4 ; 堀 智昭 4 ; 西谷 望 4
TAKAHASHI, Naoko1∗ ; KASABA, Yasumasa1 ; SHINBORI, Atsuki2 ; NISHIMURA, Yukitoshi3 ;KIKUCHI, Takashi4 ; HORI, Tomoaki4 ; NISHITANI, Nozomu41

東北大学大学院理学研究科, 2 京都大学生存圏研究所, 3 University of California, Los Angeles, 4 名古屋大学太陽地球環境研究所
1
Tohoku Univ., 2 Research Institute for Sustainable Humanosphere, Kyoto University, 3 University of California, Los Angeles,
4
Solar-Terrestrial Environment Laboratory, Nagoya University

Magnetic impulses triggered by the input from the solar wind lead to the variation of the particle and electromagnetic field.
Sudden commencements (SCs), known as one of the most distinct magnetospheric disturbance phenomena, are triggered by thecompression of the magnetosphere due to solar wind disturbances. Unlike magnetic storms and substorms, SCs can be identified
as sharp magnetic variations on the global scale. Since SCs are isolated phenomena, their onset time and driver are relatively
easy to identify. Several spacecraft observations of the electric field have indicated that the Alfven wave launching from theionosphere toward the magnetosphere plays a crucial role in inducing the transient response of the electric field in the magnetosphere. However, this suggestion has not been tested sufficiently due to lack of the electric field observation in the ionosphere.
Therefore, the interaction in the magnetosphere?ionosphere coupled system, such as the electric field propagation and energy
transport process, is still an open issue.
Motivated by these issues, we try to investigate electric field characteristics associated with SCs by simultaneous multiple
ground-based and spacecraft observations that can recently be utilized. We investigate the evolution and propagation of electricfields during SCs using in situ electric field data obtained by five THEMIS spacecraft and two Van Allen Probes (VAPs) spacecraft. We also investigate the propagation of electric fields to/in/from ionosphere with SuperDARN radar, HF Doppler radar,and ground magnetometer data. SC events are identified by the SYM-H index provided in OMNI database and geomagnetic
field data. The event criteria were set as follows: (1) SCs occur from January 2013 to December 2014. (2) The amplitude of
the SYM-H is more than 10 nT, and its rise time is less than 5 min. (3) Preliminary Impulse (PI) is recorded on high-latitude
geomagnetic field (FSIM and FSMI stations).
We found 70 SC events satisfying these conditions. For all of them, both THEMIS and VAPs detect the enhancements of theelectric field. The direction of the electric field is westward, which is consistent with that of the magnetospheric electric fieldobserved by the Akebono satellite [Shinbori et al., 2004]. We found that the nightside magnetospheric electric field follows thedayside one within 5 s delay from the PI onset, despite the large distance between them (˜5-10 RE ). In the ionosphere, SuperDARN and HF Doppler radars detected the westward electric field during the PI phase. The PI onset time of ionospheric electricfield is almost same (within 5 s) with the magnetospheric electric field detected by THEMIS and VAPs regardless of local time,
which indicates the simultaneous response between magnetospheric and ionospheric electric fields. These results suggest thatthe electric field propagates from dayside to nightside magnetospheres via the ionosphere. That is, the dayside magnetosphericelectric field propagates into the polar ionosphere along the magnetic field line, and then from polar toward low-latitude ionospheres at the speed of light between the ionosphere and ground propagation path. On the other hand, the ionospheric electricfield propagates within 5 s toward the plasmasphere and inner magnetosphere (˜5-10 RE ). Although previous results have shownthat the electric field associated with SCs is propagated into the magnetosphere by the Alfven wave along the magnetic fieldlines, the propagation velocity estimated by our observational results may be faster than the velocity of the Alfven wave.
In this paper, we report the validity of these data interpretation. We will also present the statistical results (i.e., the superposed
epoch analysis) and the Poynting fluxes that play a crucial part in the energy transmission associated with the PI onset of electricfields, which is expected to clarify the propagation path of the electric field.

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PEM09-P08

会場:コンベンションホール

時間:5 月 27 日 18:15-19:30

Dp2 イベント時の極域から磁気赤道域にかけてのグローバル電離圏電流系の特徴
The feature of global current circuit in the ionosphere from polar to dip equator during
Dp2 event松下 拓輝 1∗ ; 吉川 顕正 2 ; 魚住 禎司 3
MATSUSHITA, Hiroki1∗ ; YOSHIKAWA, Akimasa2 ; UOZUMI, Teiji31

九州大学大学院理学府地球惑星科学専攻, 2 九州大学理学研究院地球惑星科学部門, 3 九州大学国際宇宙天気科学教育センター
1Department of Earth and Planetary Sciences, Graduate School of Sciences, Kyushu University, 2 Department of Earth andPlanetary Sciences, Graduate School of Sciences, Kyushu University, 3 International Center for the Space Weather Science and
Education, Kyushu University

In the ionosphere, it is well known that the electromagnetic coupling is formed globally from polar region to dip equator region
in daytime seen as penetration of electric field during Dp2 events. Yoshikawa et al., [2012, AGU] suggests the formation of thecurrent system by Cowling channel model as the explanation of this coupling. The highly gradient of electric conductivity at theterminator between sunlit region and shaded region at dawn and dusk sides is assumed in this paper, which produces positive
polarization electric field there and this electric field forms the connection between polar and dip equator.
In our previous study, the asymmetry of the ionospheric electric field, which is calculated from observed magnetic field
variation and the model of conductivity, is found between morning side and afternoon side in the dip equator region, and we
concluded that the positive electric charge at both dawn side and dusk side by Cowling channel formation enhances and weakens
at dawn side and dusk side, which are primary positive and negative electric fields respectively. However, it was still not clearthat there is actually such asymmetry in not only dip equator region but also in global.
To clarify this existence of global asymmetric feature of the electric field and the possibility of the formation of global Dp2
current system by Cowling channel model, we investigated global feature of Dp2 variation on simultaneous and multipoint
observations. More than 200 stations data are used in this study, and their spatial distributions are from approximately -85 to
85 degree of geomagnetic latitude. The result shows that there is obvious asymmetry on the polarity of horizontal componentof Dp2 variation in low and mid latitude region between morning side and afternoon side, but not obvious asymmetry in polar
region. This unclear asymmetry in polar region might be because of the complexity of primary electric field which is penetrated
from magnetosphere.

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PEM09-P09

会場:コンベンションホール

時間:5 月 27 日 18:15-19:30

Study on Omega signals detected by Poynting Flux analyzer onboard Akebono
Study on Omega signals detected by Poynting Flux analyzer onboard Akebono
Suarjaya I Made Agus Dwi1∗ ; 笠原 禎也 1 ; 後藤 由貴 1
SUARJAYA, I made agus dwi1∗ ; KASAHARA, Yoshiya1 ; GOTO, Yoshitaka1
1
1

Kanazawa University
Kanazawa University

The Akebono satellite was launched 1989 to observe the Earth’s magnetosphere and plasmasphere. Wave normal and Poynting
flux Analyzer (PFX) subsystem is equipped on the spacecraft. It measures two components of electric field (Ex and Ey) and threecomponents of magnetic field (B1, B2, and B3) with band-width of 50 Hz in a frequency range from 100 Hz to 12.75 kHz. The
center frequency of the PFX can be changed by command. By using the PFX, we measure the signals at 10.2 kHz transmitted
from the omega stations which were operated until 1997. This omega signal was intended to be used as navigation signal similar
to GPS nowadays. By automatically detecting the omega signals included in the PFX data, we study propagation patterns of VLF
waves across the plasmasphere, because the propagation characteristics are strongly affected by plasma density and ambient
magnetic field. First we developed a method to detect the omega signals automatically and accurately, especially for the delay
time and signal existence within specific earth coordinate and time span observed by the Akebono satellite. The PFX datameasures 5 channels which correspond to 3 axis of magnetic field (B1, B2, B3) and 2 axis of electric field (Ex, Ey) in satellite
coordinate. The waveform data with band-width of 50 Hz centered at 10.2 kHz are sampled at rate of 320 Hz and sent to theground by PCM telemetry. As for the omega signal, the omega station was transmitting its signal with transmission pattern every
10 s. Each station transmitted a different pattern of frequency but has common frequency at 10.2 kHz. By using this 10.2 kHz
signal and the detection time represented by UTC on the satellite, we can determine when and which station was transmitting
the signal. As for the detection algorithm, we first estimate the delay time of each signal by comparing average intensity of
specific time frame then expecting sudden increase of intensity based on specific threshold on the expected omega signal’s timeand duration. Second, we detect the signal existence by comparing the intensity of expected omega signal’s time and duration
with the surrounding intensity based on specific threshold. In this study we used advanced detection algorithm to process hugeamounts of several years’ data. The algorithm enables us to distinguish noises and real omega signal and also handle the error
detection to produce more accurate result. Currently we have analyzed data sets from 1989 to 1990. We found that the magnetic
field intensity of the signal become weaker and the electric field intensity become higher on the other part of earth hemispherefar from the original transmission station. We will analyze further data sets from 1991 to 1997 for more credible analysis anddiscovery.
キーワード: VLF 波動, Omega 信号, プラズマ圏, あけぼの衛星, 信号処理
Keywords: VLF wave, Omega signal, Plasmasphere, Akebono satellite, Signal processing

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PEM09-P10

会場:コンベンションホール

時間:5 月 27 日 18:15-19:30

Ground-based observation of fine structures of MF/HF auroral radio emissions
Ground-based observation of fine structures of MF/HF auroral radio emissions
佐藤 由佳 1∗ ; 小川 泰信 1 ; 熊本 篤志 2 ; 上野 玄太 3
SATO, Yuka1∗ ; OGAWA, Yasunobu1 ; KUMAMOTO, Atsushi2 ; UENO, Genta3
1
1

国立極地研究所, 2 東北大学大学院理学研究科, 3 統計数理研究所
National Institute of Polar Research, 2 Graduate School of Science, Tohoku University, 3 The Institute of Statistical Mathematics

The terrestrial auroral ionosphere is a natural source of electromagnetic waves in the MF/HF ranges (up to 6 MHz) as well as
well-known intense VLF/LF emissions (auroral kilometric radiation and auroral hiss). In the MF/HF ranges, three types havebeen identified at ground level: auroral hiss, medium frequency burst (MFB), and auroral roar. In addition, recent studies haveresulted in ground-level detection of auroral kilometric radiation [LaBelle and Anderson, 2011] and discovery of a natural radio
emission between fce and 2fce [Broughton et al., 2014]. Previous studies have also shown that observation of fine structures
open new frontiers for these auroral radio emissions [e.g., LaBelle et al., 1995; Shepherd et al., 1997; Ye et al., 2006; Bunchand LaBelle, 2009]. In August 2008, we installed new instrumentation referred to as Auroral Radio Spectrograph (ARS) at
Kjell Henriksen Observatory (KHO) in Svalbard (latitude 78.15o N, longitude 16.04o E, 75.2o magnetic latitude). ARS consistsof magnetic loop antennas whose size is 2.7 m × 6.0 m and two types of receivers: ARS-S and ARS-WF. The former isdesigned for the continuous measurement of wave spectra with a time resolution of 1 sec, and the latter is designed to obtainwaveform data digitalized by an A/D converter with a sampling rate of 10 M samples/s (Nyquist frequency 5 MHz). Using ARSWF, we succeeded in the first simultaneous measurements of structured 2fce auroral roar and optical aurora during 1710-1750
UT on February 1, 2011. In this event, the structured 2fce auroral roar showed temporal evolutions in frequency band width(300 Hz at minimum) and frequency drift rate (15 kHz/s at maximum). However, because ARS-WF recorded a series of 8 M
samples (i.e., only 800-msec data) once every 40 sec, it was difficult to capture the entire temporal evolution of the structured
auroral roar. In order to solve this problem, we carry out development and trial manufacture of a new receiver using USRPT M(Universal Software Radio Peripheral). Such software-defined radio (SDR) receiver can implement high-speed, flexible digital
signal processing of RF signals. This new receiver is designed to obtain higher-resolution spectra of RF signals pauselessly
throughout the night in a wide frequency range up to 6 MHz. It is installed at KHO in Svalbard in March 2015. In thispresentation, we also show detailed design of this receiver and some initial results.

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