研究者詳細 - 新堀　淳樹

Temporal and Spatial Variations of Storm Time Midlatitude Ionospheric Trough Based on Global GNSS-TEC and Arase Satellite Observations 査読有り

Shinbori A., Otsuka Y., Tsugawa T., Nishioka M., Kumamoto A., Tsuchiya F., Matsuda S., Kasahara Y., Matsuoka A., Ruohoniemi J.M., Shepherd S.G., Nishitani N.

Geophysical Research Letters 45 巻 ( 15 ) 頁： 7362 - 7370 2018年8月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Geophysical Research Letters

Temporal and spatial variations of the midlatitude ionospheric trough during a geomagnetic storm on 4 April 2017 have been investigated using Global Navigation Satellite System total electron content data together with Arase satellite observations. After the geomagnetic storm commencement, the trough minimum location moves equatorward from 60 to 48° in geomagnetic latitude within 4 hr. The trough minimum location identified from the Global Navigation Satellite System total electron content data is located near the footprint of an abrupt drop of electron density detected by the Arase High-Frequency Analyzer instrument. The longitudinal variation of the trough minimum location shows a significant variation with a scale of 1,000–2,500 km during both storm and quiet times. This phenomenon has not yet been reported by previous studies. After the onset of the storm recovery phase, the trough minimum location rapidly moves poleward back to the quiet time location within 4 hr.

DOI： 10.1029/2018GL078723

Total electron content observations by dense regional and worldwide international networks of GNSS

Total Electron Content Observations by Dense Regional and Worldwide International Networks of GNSS

Tsugawa Takuya, Nishioka Michi, Ishii Mamoru, Hozumi Kornyanat, Saito Susumu, Shinbori Atsuki, Otsuka Yuichi, Saito Akinori, Buhari Suhaila M., Abdullah Mardina, Supnithi Pornchai

JOURNAL OF DISASTER RESEARCH 13 巻 ( 3 ) 頁： 535-545 2018年6月

Tsugawa T., Nishioka M., Ishii M., Hozumi K., Saito S., Shinbori A., Otsuka Y., Saito A., Buhari S., Abdullah M., Supnithi P.

Journal of Disaster Research 13 巻 ( 3 ) 頁： 535 - 545 2018年6月

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：Journal of Disaster Research

Two-dimensional ionospheric total electron content (TEC) maps have been derived from ground-based Global Navigation Satellite System (GNSS) receiver networks and applied to studies of various ionospheric disturbances since the mid-1990s. For the purpose of monitoring and researching ionospheric conditions and ionospheric space weather phenomena, we have developed TEC maps of areas over Japan using the dense GNSS network, GNSS Earth Observation NETwork (GEONET), which consists of about 1300 stations and is operated by the Geospatial Information Authority of Japan (GSI). Currently, we are providing high-resolution, two-dimensional maps of absolute TEC, detrended TEC, rate of TEC change index (ROTI), and loss-of-lock on GPS signal over Japan on a real-time basis. Such high-resolution TEC maps using dense GNSS receiver networks are one of the most effective ways to observe, on a scale of several 100 km to 1000 km, ionospheric variations caused by traveling ionospheric disturbances and/or equatorial plasma bubbles, which can degrade single-frequency and differential GNSS positioning/navigation. We have collected all the available GNSS receiver data in the world to expand the TEC observation area. Currently, however, dense GNSS receiver networks are available in only limited areas, such as Japan, North America, and Europe. To expand the two-dimensional TEC observation with high resolution, we have conducted the Dense Regional and Worldwide International GNSS TEC observation (DRAWING-TEC) project, which is engaged in three activities: (1) standardizing GNSS-TEC data, (2) developing a new high-resolution TEC mapping technique, and (3) sharing the standardized TEC data or the information of GNSS receiver network. We have developed a new standardized TEC format, GNSS-TEC EXchange (GTEX), which is included in the Formatted Tables of ITU-R SG 3 Data-banks related to Recommendation ITU-R P.311. Sharing the GTEX TEC data would be easier than sharing the GPS/GNSS data among those in the international ionospheric researcher community. The DRAWING-TEC project would promote studies of medium-scale ionospheric variations and their effect on GNSS.

DOI： 10.20965/jdr.2018.p0535

Temporal and spatial variations of mid-latitude ionospheric trough during a geomagnetic storm based on global GNSS-TEC and Arase satellite observations 査読有り

CiNii Research

Shinbori, A; Otsuka, Y; Tsugawa, T; Nishioka, M; Kumamoto, A; Tsuchia, F; Matsuda, S; Kasahara, Y

2018 2ND URSI ATLANTIC RADIO SCIENCE MEETING (AT-RASC) 頁： . 2018年

Wire Probe Antenna (WPT) and Electric Field Detector (EFD) of Plasma Wave Experiment (PWE) aboard the Arase satellite: specifications and initial evaluation results 査読有り

Kasaba, Y; Ishisaka, K; Kasahara, Y; Imachi, T; Yagitani, S; Kojima, H; Matsuda, S; Shoji, M; Kurita, S; Hori, T; Shinbori, A; Teramoto, M; Miyoshi, Y; Nakagawa, T; Takahashi, N; Nishimura, Y; Matsuoka, A; Kumamoto, A; Tsuchiya, F; Nomura, R

EARTH PLANETS AND SPACE 69 巻 ( 174 ) 2017年12月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Earth, Planets and Space

This paper summarizes the specifications and initial evaluation results of Wire Probe Antenna (WPT) and Electric Field Detector (EFD), the key components for the electric field measurement of the Plasma Wave Experiment (PWE) aboard the Arase (ERG) satellite. WPT consists of two pairs of dipole antennas with ~ 31-m tip-to-tip length. Each antenna element has a spherical probe (60 mm diameter) at each end of the wire (15 m length). They are extended orthogonally in the spin plane of the spacecraft, which is roughly perpendicular to the Sun and enables to measure the electric field in the frequency range of DC to 10 MHz. This system is almost identical to the WPT of Plasma Wave Investigation aboard the BepiColombo Mercury Magnetospheric Orbiter, except for the material of the spherical probe (ERG: Al alloy, MMO: Ti alloy). EFD is a part of the EWO (EFD/WFC/OFA) receiver and measures the 2-ch electric field at a sampling rate of 512 Hz (dynamic range: ± 200 mV/m) and the 4-ch spacecraft potential at a sampling rate of 128 Hz (dynamic range: ± 100 V and ± 3 V/m), with the bias control capability of WPT. The electric field waveform provides (1) fundamental information about the plasma dynamics and accelerations and (2) the characteristics of MHD and ion waves in various magnetospheric statuses with the magnetic field measured by MGF and PWE–MSC. The spacecraft potential provides information on thermal electron plasma variations and structure combined with the electron density obtained from the upper hybrid resonance frequency provided by PWE–HFA. EFD has two data modes. The continuous (medium-mode) data are provided as (1) 2-ch waveforms at 64 Hz (in apoapsis mode, L > 4) or 256 Hz (in periapsis mode, L < 4), (2) 1-ch spectrum within 1–232 Hz with 1-s resolution, and (3) 4-ch spacecraft potential at 8 Hz. The burst (high-mode) data are intermittently obtained as (4) 2-ch waveforms at 512 Hz and (5) 4-ch spacecraft potential at 128 Hz and downloaded with the WFC-E/B datasets after the selection. This paper also shows the initial evaluation results in the initial observation phase.[Figure not available: see fulltext.].

DOI： 10.1186/s40623-017-0760-x

Ground-based instruments of the PWING project to investigate dynamics of the inner magnetosphere at subauroral latitudes as a part of the ERG-ground coordinated observation network 査読有り

Shiokawa, K; Katoh, Y; Hamaguchi, Y; Yamamoto, Y; Adachi, T; Ozaki, M; Oyama, SI; Nosé, M; Nagatsuma, T; Tanaka, Y; Otsuka, Y; Miyoshi, Y; Kataoka, R; Takagi, Y; Takeshita, Y; Shinbori, A; Kurita, S; Hori, T; Nishitani, N; Shinohara, I; Tsuchiya, F; Obana, Y; Suzuki, S; Takahashi, N; Seki, K; Kadokura, A; Hosokawa, K; Ogawa, Y; Connors, M; Ruohoniemi, JM; Engebretson, M; Turunen, E; Ulich, T; Manninen, J; Raita, T; Kero, A; Oksanen, A; Back, M; Kauristie, K; Mattanen, J; Baishev, D; Kurkin, V; Oinats, A; Pashinin, A; Vasilyev, R; Rakhmatulin, R; Bristow, W; Karjala, M

EARTH PLANETS AND SPACE 69 巻 ( 1 ) 2017年11月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Earth, Planets and Space

The plasmas (electrons and ions) in the inner magnetosphere have wide energy ranges from electron volts to mega-electron volts (MeV). These plasmas rotate around the Earth longitudinally due to the gradient and curvature of the geomagnetic field and by the co-rotation motion with timescales from several tens of hours to less than 10 min. They interact with plasma waves at frequencies of mHz to kHz mainly in the equatorial plane of the magnetosphere, obtain energies up to MeV, and are lost into the ionosphere. In order to provide the global distribution and quantitative evaluation of the dynamical variation of these plasmas and waves in the inner magnetosphere, the PWING project (study of dynamical variation of particles and waves in the inner magnetosphere using ground-based network observations, http://www.isee.Nagoya-u.ac.jp/dimr/PWING/) has been carried out since April 2016. This paper describes the stations and instrumentation of the PWING project. We operate all-sky airglow/aurora imagers, 64-Hz sampling induction magnetometers, 40-kHz sampling loop antennas, and 64-Hz sampling riometers at eight stations at subauroral latitudes (~ 60° geomagnetic latitude) in the northern hemisphere, as well as 100-Hz sampling EMCCD cameras at three stations. These stations are distributed longitudinally in Canada, Iceland, Finland, Russia, and Alaska to obtain the longitudinal distribution of plasmas and waves in the inner magnetosphere. This PWING longitudinal network has been developed as a part of the ERG (Arase)-ground coordinated observation network. The ERG (Arase) satellite was launched on December 20, 2016, and has been in full operation since March 2017. We will combine these ground network observations with the ERG (Arase) satellite and global modeling studies. These comprehensive datasets will contribute to the investigation of dynamical variation of particles and waves in the inner magnetosphere, which is one of the most important research topics in recent space physics, and the outcome of our research will improve safe and secure use of geospace around the Earth.[Figure not available: see fulltext.]

DOI： 10.1186/s40623-017-0745-9

Characteristics of Seasonal Variation and Solar Activity Dependence of the Geomagnetic Solar Quiet Daily Variation 査読有り

Shinbori, A; Koyama, Y; Nosé, M; Hori, T; Otsuka, Y

JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS 122 巻 ( 10 ) 頁： 10796 - 10810 2017年10月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：American Geophysical Union ({AGU})

Characteristics of seasonal variation and solar activity dependence of the X and Y components of the geomagnetic solar quiet (Sq) daily variation at Memambetsu in midlatitudes and Guam near the equator have been investigated using long-term geomagnetic field data with 1 h time resolution from 1957 to 2016. The monthly mean Sq variation in the X and Y components (Sq-X and Sq-Y) shows a clear seasonal variation and solar activity dependence. The amplitude of seasonal variation increases significantly during high solar activities and is proportional to the solar F10.7 index. The pattern of the seasonal variation is quite different between Sq-X and Sq-Y. The result of the correlation analysis between the solar F10.7 index and the Sq-X and Sq-Y shows an almost linear relationship, but the slope of the linear fitted line varies as a function of local time and month. This implies that the sensitivity of Sq-X and Sq-Y to the solar activity is different for different local times and seasons. The pattern of the local time and seasonal variations of Sq-Y at Guam shows good agreement with that of a magnetic field produced by interhemispheric field-aligned currents (FACs), which flow from the summer to winter hemispheres in the dawn and dusk sectors and from the winter to summer hemispheres in the prenoon to afternoon sectors. The direction of the interhemispheric FAC in the dusk sector is opposite to the concept of Fukushima's model.

DOI： 10.1002/2017JA024342

Propagation and evolution of electric fields associated with solar wind pressure pulses based on spacecraft and ground-based observations 査読有り

Takahashi, N; Kasaba, Y; Nishimura, Y; Shinbori, A; Kikuchi, T; Hori, T; Ebihara, Y; Nishitani, N

JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS 122 巻 ( 8 ) 頁： 8446 - 8461 2017年8月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Journal of Geophysical Research: Space Physics

We investigate spatial and temporal evolution of large-scale electric fields in the magnetosphere and ionosphere associated with sudden commencements (SCs) using multipoint equatorial magnetospheric (THEMIS, RBSP, and GOES) and ionospheric (C/NOFS) satellites with radars (SuperDARN). A distinct SC event on 17 March 2013 shows that the magnetospheric electric field in the equatorial plane propagates from dayside toward nightside as a fast-mode wave. The ionospheric electric field responds ~41 s after the onset of dayside magnetospheric electric field, which can be explained by the propagation of the Alfvén wave along magnetic field lines. The wavelet analysis shows that the Alfvén wave is dominant in the plasmasphere. Poynting fluxes toward the ionosphere support these propagations. From a statistical analysis of response time, tailward propagation speed is estimated at about 1000–1100 km/s. We also statistically derive a spatial distribution and time evolution of the magnetospheric electric field in the dawn-dusk direction (Ey). Our result shows that negative Ey (dawnward) propagates from noon toward the magnetotail, followed by positive Ey (duskward). The propagation characteristics of electric fields in the equatorial plane depend on magnetic local time. At noon, negative Ey lasts for about 1 min, and positive Ey becomes dominant about 2 min after the SC onset. Negative Ey soon attenuates in the nightside region, while the positive Ey propagates fairly well to the premidnight or postmidnight regions while maintaining a certain amplitude. The enhancement of positive Ey is due to the enhancement of magnetospheric convection associated with the main impulse of SCs.

DOI： 10.1002/2017JA023990

その他リンク： http://orcid.org/0000-0002-8160-3553

京大RISHにおける生存圏データベースの公開

橋口浩之, 津田敏隆, 塩谷雅人, 山本衛, 杉山淳司, 新堀淳樹

科学データ研究会・WDS国内シンポジウム 2017年3月

生存圏アジアリサーチノード

津田敏隆, 橋口浩之, 森拓郎, 新堀淳樹

生存圏ミッションシンポジウム 2017年2月

Thermal and Low-energy Ion Outflows in and through the Polar Cap 査読有り

Naritoshi Kitamura, Kanako Seki, Yukitoshi Nishimura, Takumi Abe, Manabu Yamada, Shigeto Watanabe, Atsushi Kumamoto, Atsuki Shinbori, Andrew W. Yau

Magnetosphere-Ionosphere Coupling in the Solar System 頁： 91 - 100 2016年10月

Evaluation of momentum flux with radar 査読有り

Dennis M. Riggin, Toshitaka Tsuda, Atsuki Shinbori

JOURNAL OF ATMOSPHERIC AND SOLAR-TERRESTRIAL PHYSICS 142 巻頁： 98 - 107 2016年5月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：PERGAMON-ELSEVIER SCIENCE LTD

The statistics of gravity wave momentum flux estimation are investigated using data from the MU radar at Shigariki, Japan (136 degrees E, 35 degrees N). The radar has been operating during campaign periods since 1986. The first part of the paper focuses on a multi-day campaign during October 13-31, 1986. The second part of the paper investigates data after 2006 when the radar was operated in a meteor scatter mode. Momentum fluxes are derived from both the turbulent scatter and the meteor scatter measurements, but the techniques are quite different. Probability Distribution Functions are formed using turbulent scatter data. These show that wave packets sometimes have momentum flux magnitudes in excess of 100 m(2) s(-2). The technique for meteor radars, introduced by Hocking (2005), has been widely adopted by the radar community in recent years. The momentum flux estimated using this technique is found to be anti-correlated with the background tidal winds. A validation investigation is carried out for periods with a high meteor echo data rate. The conclusion was that the method can be used to calculate the sign of momentum flux, but does not accurately specify the magnitude. (C) 2016 The Authors. Published by Elsevier Ltd.

DOI： 10.1016/j.jastp.2016.01.013

Relationship between solar wind dynamic pressure and amplitude of geomagnetic sudden commencement (SC) 査読有り

Tohru Araki, Atsuki Shinbori

EARTH PLANETS AND SPACE 68 巻 ( 1 ) 2016年5月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：SPRINGER HEIDELBERG

The local time variation of geomagnetic sudden commencements (SCs) has not been taken into account in the Siscoe's linear relationship which connects the SC amplitude with the corresponding dynamic pressure variation of the solar wind. By considering the physical background of SC, we studied which local time is best to extract the information of the solar wind dynamic pressure and concluded that the SC amplitude at 4-5 h local time of middle and low-latitude stations most directly reflects the dynamic pressure effect. This result is used to re-check the order of magnitude of the largest 3 SCs observed since 1868.

DOI： 10.1186/s40623-016-0444-y

Response of the incompressible ionosphere to the compression of the magnetosphere during the geomagnetic sudden commencements 査読有り

Simultaneous ground‐ and satellite‐based observation of MF/HF auroral radio emissions 査読有り

Yuka Sato, Atsushi Kumamoto, Yuto Katoh, Atsuki Shinbori, Akira Kadokura, Yasunobu Ogawa

Journal of Geophysical Research, Space Physics 121 巻頁： 4530 - 4541 2016年5月

JavaFX-based iUgonet Data Analysis Software (JudasFX)のプロトタイプ開発査読有り

小山幸伸, 佐藤由佳, 中野慎也, 八木学, 田中良昌, 阿部修司, 能勢正仁, 蔵川圭, 池田大輔, 梅村宜生, 新堀淳樹, 上野悟

宇宙科学情報解析論文誌 ( 第5号 ) 2016年3月

Kikuchi, T; Hashimoto, KK; Tomizawa, I; Ebihara, Y; Nishimura, Y; Araki, T; Shinbori, A; Veenadhari, B; Tanaka, T; Nagatsuma, T

JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS 121 巻 ( 2 ) 頁： 1536 - 1556 2016年2月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Journal of Geophysical Research: Space Physics

The ionospheric plasma in midlatitude moves upward/downward during the geomagnetic sudden commencement causing the HF Doppler frequency changes; SCF (+ -) and (- +) on the dayside and nightside, respectively, except for the SCF (+ -) in the evening as found by Kikuchi et al. (1985). Although the preliminary and main frequency deviations (PFD, MFD) of the SCF have been attributed to the dusk-to-dawn and dawn-to-dusk potential electric fields, there still remain questions if the positive PFD can be caused by the compressional magnetohydrodynamic (MHD) wave and what causes the evening anomaly of the SCF. With the HF Doppler sounder, we show that the dayside ionosphere moves upward toward the Sun during the main impulse (MI) of the SC, when the compressional wave is supposed to push the ionosphere downward. The motion of the ionosphere is shown to be correlated with the equatorial electrojet, matching the potential electric field transmitted with the ionospheric currents from the polar ionosphere. We confirmed that the electric field of the compressional wave is severely suppressed by the conducting ionosphere and reproduced the SC electric fields using the global MHD simulation in which the potential solver is employed. The model calculations well reproduced the preliminary impulse and MI electric fields and their evening anomaly. It is suggested that the electric potential is transmitted from the polar ionosphere to the equator by the zeroth-order transverse magnetic (TM0) mode waves in the Earth-ionosphere waveguide. The near-instantaneous transmission of the electric potential leads to instantaneous global response of the incompressible ionosphere.

DOI： 10.1002/2015JA022166

Measurement of momentum flux using two meteor radars in Indonesia 査読有り

Naoki Matsumoto, Atsuki Shinbori, Dennis M. Riggin, Toshitaka Tsuda

ANNALES GEOPHYSICAE 34 巻 ( 3 ) 頁： 369 - 377 2016年

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：COPERNICUS GESELLSCHAFT MBH

Two nearly identical meteor radars were operated at Koto Tabang (0.20 degrees S, 100.32 degrees E), West Sumatra, and Biak (1.17 degrees S, 136.10 degrees E), West Papua, in Indonesia, separated by approximately 4000 km in longitude on the Equator. The zonal and meridional momentum flux, u'w' and v'w', where u, v, and w are the eastward, northward, and vertical wind velocity components, respectively, were estimated at 86 to 94 km altitudes using the meteor radar data by applying a method proposed by Hocking (2005). The observed u'w' at the two sites agreed reasonably well at 86, 90, and 94 km during the observation periods when the data acquisition rate was sufficiently large enough. Variations in v'w' were consistent between 86, 90, and 94 km altitudes at both sites. The climatological variation in the monthly averaged u'w' and v'w' was investigated using the long-term radar data at Koto Tabang from November 2002 to November 2013. The seasonal variations in u'w' and v'w' showed a repeatable semiannual and annual cycles, respectively. u'w' showed eastward values in February-April and July-September and v'w' was northward in June to August at 90-94 km, both of which were generally anti-phase with the mean zonal and meridional winds, having the same periodicity. Our results suggest the usefulness of the Hocking method.

DOI： 10.5194/angeo-34-369-2016