Faculty Profiles - SHINBORI Atsuki

Relationship between solar wind dynamic pressure and amplitude of geomagnetic sudden commencement (SC) Reviewed

Tohru Araki, Atsuki Shinbori

EARTH PLANETS AND SPACE Vol. 68 ( 1 ) 2016.5

Language：English Publishing type：Research paper (scientific journal) Publisher：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 Reviewed

Simultaneous ground‐ and satellite‐based observation of MF/HF auroral radio emissions Reviewed

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

Journal of Geophysical Research, Space Physics Vol. 121 page： 4530 - 4541 2016.5

Prototype Development of the JavaFX-based iUgonet Data Analysis Software (JudasFX) Reviewed

Yukinobu KOYAMA, Yuka SATO, Shinya NAKANO, Manabu YAGI, Yoshimasa TANAKA, Shuji ABE, Masahito NOSE, Kei KURAKAWA, Daisuke IKEDA, Norio UMEMURA, Atsuki SHINBORI, Satoru UeNo

Journal of Space Science Informatics Japan ( 第5号 ) 2016.3

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

JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS Vol. 121 ( 2 ) page： 1536 - 1556 2016.2

Language：English Publishing type：Research paper (scientific journal) Publisher：AMER GEOPHYSICAL UNION

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 Reviewed

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

ANNALES GEOPHYSICAE Vol. 34 ( 3 ) page： 369 - 377 2016

Language：English Publishing type：Research paper (scientific journal) Publisher：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

IMF-By dependence of transient ionospheric flow perturbation associated with sudden impulses: SuperDARN observations Reviewed

JavaFX-based iUgonet Data Analysis Software (JudasFX)のプロトタイプ開発 Reviewed

小山幸伸, 池田大輔, 新堀淳樹, 堀智昭

宇宙科学情報解析論文誌 Vol. 5 page： 81 - 92 2016

Tomoaki Hori, Atsuki Shinbori, Shigeru Fujita, Nozomu Nishitani

EARTH PLANETS AND SPACE Vol. 67 ( 1 ) 2015.11

Language：English Publishing type：Research paper (scientific journal) Publisher：SPRINGER HEIDELBERG

A statistical study using a large dataset of Super Dual Auroral Radar Network (SuperDARN) observations is conducted for transient ionospheric plasma flows associated with sudden impulses (SI) recorded on ground magnetic field. The global structure of twin vortex-like ionospheric flows is found to be consistent with the twin vortices of ionospheric Hall current deduced by the past geomagnetic field observations. An interesting feature, which is focused on in this study, is that the flow structures show a dawn-dusk asymmetry depending on the combination of the polarity of SI and interplanetary magnetic field (IMF)-By. Detailed statistics of the SuperDARN observations reveal that the dawn-dusk asymmetry of flow vortices due to IMF-By appears during negative SIs, while such asymmetric characteristics are not seen during positive SIs. On the basis of the upstream observations, we suggest that this particular dawn-dusk asymmetry is caused by the interaction between the pre-existing round convection cell and a pair of the transient convection vortices associated with SIs.

DOI： 10.1186/s40623-015-0360-6

Response of ionospheric electric fields at mid-low latitudes during sudden commencements Reviewed

N. Takahashi, Y. Kasaba, A. Shinbori, Y. Nishimura, T. Kikuchi, Y. Ebihara, T. Nagatsuma

JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS Vol. 120 ( 6 ) page： 4849 - 4862 2015.6

Language：English Publishing type：Research paper (scientific journal) Publisher：AMER GEOPHYSICAL UNION

Using in situ observations from the Republic of China Satellite-1 spacecraft, we investigated the time response and local time dependence of the ionospheric electric field at mid-low latitudes associated with geomagnetic sudden commencements (SCs) that occurred from 1999 to 2004. We found that the ionospheric electric field variation associated with SCs instantaneously responds to the preliminary impulse (PI) signature on the ground regardless of spacecraft local time. Our statistical analysis also supports the global instant transmission of electric field from the polar region. In contrast, the peak time detected in the ionospheric electric field is earlier than that of the equatorial geomagnetic field (similar to 20s before in the PI phase). Based on the ground-ionosphere waveguide model, this time lag can be attributed to the latitudinal difference of ionospheric conductivity. However, the local time distribution of the initial excursion of ionospheric electric field shows that dusk-to-dawn ionospheric electric fields develop during the PI phase. Moreover, the westward electric field in the ionosphere, which produces the preliminary reverse impulse of the geomagnetic field on the dayside feature, appears at 18-22h LT where the ionospheric conductivity beyond the duskside terminator (18h LT) is lower than on the dayside. The result of a magnetohydrodynamic simulation for an ideal SC shows that the electric potential distribution is asymmetric with respect to the noon-midnight meridian. This produces the local time distribution of ionospheric electric fields similar to the observed result, which can be explained by the divergence of the Hall current under nonuniform ionospheric conductivity.

DOI： 10.1002/2015JA021309

The capacity-building and science-enabling activities of the IUGONET for the solar-terrestrial research community Reviewed

Yatagai, A; Sato, Y; Shinbori, A; Abe, S; UeNo, S

EARTH PLANETS AND SPACE Vol. 67 ( 1 ) 2015.1

Language：English Publishing type：Research paper (scientific journal) Publisher：Earth, Planets and Space

Background: This paper presents an overview of the capacity-building activities and science-enabling services of the Inter-university Upper atmosphere Global Observation NETwork (IUGONET) project. This Japanese program, which started in 2009, is building a metadata database (MDDB) of ground-based observations and is developing an analysis software to handle the data linked to the MDDB system for use by the solar-terrestrial physics community. Because the institutional members of the IUGONET are mainly universities in Japan, we explore tools that can contribute to advanced education as well as promote research activities. Findings: In this paper, we describe the utilities of the IUGONET for education, including our capacity-building activities in developing countries. We have regularly facilitated training seminars for Japanese students on the use of our tools (IUGONET MDDB and the software), and we have held capacity-building seminars for young scientists in developing countries. In addition to the MDDB, we have prepared various 'gateway' tools for users who are unfamiliar with 'keywords' to search for data. One of these is a geographical display tool that uses Google Earth (KML file), which is included as supplemental material to this paper. The usefulness of the IUGONET has been proven over its first 5 years of operation by the increasing number of its users, which has led to the production of approximately 500 scientific papers, including 42 thesis papers. Conclusions: The IUGONET community collaborates with the Scientific Committee on Solar-Terrestrial Physics program, not only in its scientific activities, but also in the establishment of E-infrastructure and capacity building.

DOI： 10.1186/s40623-014-0170-2

Long-term variation in the upper atmosphere as seen in the geomagnetic solar quiet daily variation Reviewed

Thermal and low-energy ion outflows in and through the polar cap: The polar wind and the low-energy component of the cleft ion fountain Reviewed

Kitamura, N, K. Seki, Y. Nishimura, T. Abe, M. Yamada, S. Watanabe, A. Kumamoto, A. Shinbori, A. W. Yau

AGU Geophysical Monograph 2015

Shinbori, A; Koyama, Y; Nose, M; Hori, T; Otsuka, Y; Yatagai, A

EARTH PLANETS AND SPACE Vol. 66 ( 1 ) page： 1 - 20 2014.12

Language：English Publishing type：Research paper (scientific journal) Publisher：Earth, Planets and Space

Characteristics of long-term variation in the amplitude of solar quiet (Sq) geomagnetic field daily variation have been investigated using 1-h geomagnetic field data obtained from 69 geomagnetic observation stations within the period of 1947 to 2013. The Sq amplitude observed at these geomagnetic stations showed a clear dependence on the 10- to 12-year solar activity cycle and tended to be enhanced during each solar maximum phase. The Sq amplitude was the smallest around the minimum of solar cycle 23/24 in 2008 to 2009. The relationship between the solar F10.7 index and Sq amplitude was approximately linear but about 53% of geomagnetic stations showed a weak nonlinear relation to the solar F10.7 index. In order to remove the effect of solar activity seen in the long-term variation of the Sq amplitude, we calculated a linear or second-order fitting curve between the solar F10.7 index and Sq amplitude during 1947 to 2013 and examined the residual Sq amplitude, which is defined as the deviation from the fitting curve. As a result, the majority of trends in the residual Sq amplitude that passed through a trend test showed negative values over a wide region. This tendency was relatively strong in Europe, India, the eastern part of Canada, and New Zealand. The relationship between the magnetic field intensity at 100-km altitude and residual Sq amplitude showed an anti-correlation for about 71% of the geomagnetic stations. Furthermore, the residual Sq amplitude at the equatorial station (Addis Ababa) was anti-correlated with the absolute value of the magnetic field inclination. This implies movement of the equatorial electrojet due to the secular variation of the ambient magnetic field.

DOI： 10.1186/s40623-014-0155-1

An Interactive Data Language software package to calculate ionospheric conductivity by using numerical models Reviewed

Yukinobu Koyamaa, Atsuki Shinbori, Yoshimasa Tanaka, Tomoaki Hori, Masahito Nose, Satoshi Oimatsu

COMPUTER PHYSICS COMMUNICATIONS Vol. 185 ( 12 ) page： 3398 - 3405 2014.12

Language：English Publishing type：Research paper (scientific journal) Publisher：ELSEVIER SCIENCE BV

The Inter-university Upper atmosphere Global Observation NETwork (IUGONET) project focuses on handling ground-based observational data of the upper atmosphere. To this end, the project members have been developing a data analysis software package which is based on Interactive Data Language (IDL). Filling the spatial gaps in observational data requires the use of numerical models. In this paper, we discuss an IDL software package for global ionospheric conductivity by integration of 3rd party numerical models. The model can be used to create further derived models. (C) 2014 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.cpc.2014.08.011

Interuniversity Upper Atmosphere Global Observation NETwork (IUGONET) meta-database and analysis software Reviewed

Long-term variation in the upper atmosphere as seen in the geomagnetic solar quiet daily variation Reviewed

Shinbori, A, Y. Koyama, M, Nose, T. Hori, Y. Otsuka, A. Yatagai

Earth, Planets and Space Vol. 65 ( 155 ) 2014.12

The capacity-building and science-enabling activities of the IUGONET to the solar-terrestrial research community Reviewed

Yatagai, A, Y. Sato, A. Shinbori, S. Abe, S. UeNo, IUGONET Team

Earth, Planets and Space 2014.12

A. Yatagai, Y. Tanaka, S. Abe, A. Shinbori, M. Yagi, S. UeNo, Y. Koyama, N. Umemura, M. Nosé, T. Hori, Y. Sato, N. O. Hashiguchi, N. Kaneda

Data Science Journal Vol. 13 ( 0 ) page： PDA37 - PDA43 2014.10

Language：English Publishing type：Research paper (scientific journal) Publisher：Committee on Data for Science and Technology

An overview of the Interuniversity Upper atmosphere Global Observation NETwork (IUGONET) project is presented. This Japanese program is building a meta-database for ground-based observations of the upper atmosphere, in which metadata connected with various atmospheric radars and photometers, including those located in both polar regions, are archived. By querying the metadata database, researchers are able to access data file/information held by data facilities. Moreover, by utilizing our analysis software, users can download, visualize, and analyze upper-atmospheric data archived in or linked with the system. As a future development, we are looking to make our database interoperable with others.

DOI： 10.2481/dsj.IFPDA-07

CiNii Research

Progress of the IUGONET system - metadata database for upper atmosphere ground-based observation data Reviewed

Shuji Abe, Norio Umemura, Yukinobu Koyama, Yoshimasa Tanaka, Manabu Yagi, Akiyo Yatagai, Atsuki Shinbori, Satoru UeNo, Yuka Sato, Naoki Kaneda

EARTH PLANETS AND SPACE Vol. 66 ( 133 ) 2014.10

Language：English Publishing type：Research paper (scientific journal) Publisher：SPRINGER HEIDELBERG

Background: The Interuniversity Upper atmosphere Global Observation NETwork (IUGONET) project is a 6-year research project which started in 2009. The objective of this project is to establish a metadata database of various ground-based observation data covering a wide region from the Sun to the Earth; this will encourage more studies on the mechanisms of long-term variations in the upper atmosphere.
Findings: For archiving purposes, the metadata database system for cross-searching various data distributed across many universities and institute was developed based on the existing repository software called DSpace as the core component and the Space Physics Archive Search and Extract (SPASE) data model as the metadata format. The IUGONET metadata database is still in operation since it was released in March 2012. The system is continuously examined, tested, and updated to improve its quality. The OpenSearch interface in the IUGONET metadata database allows the user to use external applications easily for exchanging metadata and/or for analyzing data.
Conclusions: We conducted self-examination of our product, which was added for planning future directions of the IUGONET project.

DOI： 10.1186/1880-5981-66-133

Application of associative search to the metadata database of the upper atmosphere Reviewed

KOYAMA Yukinori, ABE Shuji, YAGI Manabu, UMEMURA Norio, HORI Tomoaki, SHINBORI Atsuki, SATO Yuka, IYEMORI Toshihiko, TANAKA Yoshimasa, HASHIGUCHI Noriko, UENO Satoru, YATAGAI Akiyo

JAXA research and development report Vol. 13 page： 89 - 97 2014.3

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：宇宙航空研究開発機構

In order to understand the mechanism of global-scale phenomena in the upper atmosphere, multidisciplinary researches using many kinds of data are important. An infrastructure to access to many kinds of data on the Internet is one of the keys to the multidisciplinary researches. The Inter-university Upper atmosphere Global Observation NETwork (IUGONET) project solved this problem by developing a metadata database to provide information such as URL of database or each data .le, which are managed dispersively by several institutes. Because the metadata database covers a wide scienti.c .eld, it is likely that non-specialized users can not easily select a right search phrase. We connected an associative search engine which is called GETAssoc with the metadata database, in order to get the related words and to generate re-query phrases by using them automatically. We collected metadata from SAO/NASA Astrophysics Data System to create the dictionary for associative search. We show that the prepared dictionary gives the related terms as expected for generating re-query phrases.

CiNii Research