| 1. |
Higuchi, H, and A. Yoshikawa, Electron acceleration mechanism in "ionospheric polarized Poleward Boundary Intensification": A new validation with 3-dimensional fluid electron acceleration simulators, American Geophysics Union Fall Meeting 2021, 2021.12. |
| 2. |
M. Hayashi, A.Yoshikawa, A.Fujimoto, S.Ohtani, Research on the Poler to Mid-latitude Ionospheric Response During Substorm based on mid-latitude electric field and global magnetic field observations, American Geophysics Union Fall Meeting 2021, 2021.12. |
| 3. |
Takayama Kumi, Yoshikawa Akimasa , Principal Component Analysis for Extracting Variations due to Sq Current and Atmospheric Tides from Magnetic Field Data, American Geophysics Union Fall Meeting 2021, 2021.12. |
| 4. |
Yasunaga Akihiro、Akimasa Yoshikawa, and Fujimoto Akiko, Research on the unique Solar Flare Effect (SFE*) at the dip equator around local noon, AOGS Annual Virtual Meeting 2021, 2021.08. |
| 5. |
Takayama Kumi, Yoshikawa Akimasa, and Miyoshi Yasunobu, Quasi-6-Day Wave Effect on Electric Conductivity, Electric field, and Current with GAIA model, AOGS Annual Virtual Meeting 2021, 2021.08. |
| 6. |
＃M.Hayashi, ＠A.Yoshikawa, A.Fujimoto, S.Ohtani,, Research for formation of global current system during substorm through observation of ionospheric response at mid-latitudinal region, AOGS Annual Virtual Meeting 2021, 2021.08. |
| 7. |
山本 衛、橋口 浩之、横山 竜宏、宮岡 宏、小川 泰信、塩川 和夫、野澤 悟徳、＠吉川 顕正、津田 敏隆, Study of coupling processes in the solar-terrestrial system, Japan GeoScience Meeting 2021, 2021.06. |
| 8. |
惣宇利 卓弥、新堀 淳樹、大塚 雄一、津川 卓也、西岡 未知、＠吉川 顕正, Generation mechanisms of plasma density irregularity from equatorial to midlatitude ionosphere during a geomagnetic storm on 21 and 22 December 2014, Japan GeoScience Meeting 2021, 2021.06. |
| 9. |
大矢 浩代、折戸 雄飛、土屋 史紀、山本 真行、中田 裕之、＠吉川 顕正, D-region ionospheric effects for 2016 eruptions of Mt. Aso using LF transmitter signals, Japan GeoScience Meeting 2021, 2021.06. |
| 10. |
藤本 晶子、＠阿部 修司、御厨 徹、池田 昭大、＠吉川 顕正, Multiple equatorial ionospheric observation project based on FMCW radar combining MAGDAS/SDR-based scintillation detector, Japan GeoScience Meeting 2021, 2021.06. |
| 11. |
＠吉川 顕正、＃橋本 翼、中溝 葵、大谷 晋一, Development of a novel method for extracting the geometrical properties of the magnetic vector fields towards the era of multi-point satellite observations, Japan GeoScience Meeting 2021, 2021.06. |
| 12. |
塩川 和夫, 三好 由純, ＠吉川 顕正、中村 卓司, 太陽地球系物理学科学委員会（SCOSTEP)の活動と展望：学術会議を通した国際活動の推進, Japan GeoScience Meeting 2021, 2021.06. |
| 13. |
ラナシンハ マンジュラ, 藤本 晶子, ＠吉川 顕正, ジャヤラトナ チャンダ, Seasonal dependence of dusk-side equatorial IHFACs polarity during solar cycle 23-24, Japan GeoScience Meeting 2021, 2021.06. |
| 14. |
中溝 葵, ＠吉川 顕正, 中田 裕之, 深沢 圭一郎, 田中 高史, Development of a new M-I coupling algorithm in global MHD magnetosphere simulation: Alfvénic-Coupling, Japan GeoScience Meeting 2021, 2021.06. |
| 15. |
＠Akimasa Yoshikawa, Modeling of magnetosphere-ionosphere-atmosphere system for investigation of coupling process in the space-terrestrial transition region, Japan GeoScience Meeting 2021, 2021.06. |
| 16. |
＠Kirolosse Mina Girgis, ＠Tohru Hada, ＠Shuichi Matsukiyo, ＠Akimasa Yoshikawa, , Numerical Proton Flux Response in South Atlantic Anomaly during Geomagnetic Storm, Japan GeoScience Meeting 2021, 2021.06. |
| 17. |
＃森澤将、＠吉川顕正、大谷晋一, 夜側オーロラオーバルの極側境界で起こるオーロラ増光現象の発生過程における電離圏分極の数値解析, Japan GeoScience Meeting 2021, 2021.06. |
| 18. |
＃伊集院拓也、＠吉川顕正, IGRFモデルを用いた3次元全球電離圏静電ポテンシャルソルバーの開発, Japan GeoScience Meeting 2021, 2021.06. |
| 19. |
＃Yasunaga Akihiro、Fujimoto Akiko、＠Yoshikawa Akimasa, Study on the Solar Flare Effect (SFE*) of equatorial electrojet around local noon, Japan GeoScience Meeting 2021, 2021.06. |
| 20. |
＃Takayama Kumi, ＠Yoshikawa Akimasa, and ＠Miyoshi Yasunobu, Seasonal Dependence of the Quasi-6-Day Oscillation in Sq-EEJ Current System, Japan GeoScience Meeting 2021, 2021.06. |
| 21. |
＃Higuchi, H. and ＠A. Yoshikawa, , Exploring the Electron Acceleration Mechanism in the Poleward Boundary Intensification, Japan GeoScience Meeting 2021, 2021.06. |
| 22. |
M.Hayashi, A.Yoshikawa, A.Fujimoto , S. Ohtani, Investigation of the mid-latitude ionospheric response during substorm based on magnetic and electric field observations, Japan GeoScience Meeting 2021, 2021.06. |
| 23. |
Akihiro Ikeda, Teiji Uozumi, Akimasa Yoshikaw, Akiko Fujimoto, Shuji Abe, Schumann resonance parameters at Kuju during solar flares and solar proton events, 地球電磁気･地球惑星圏学会 第148回 総会・講演会（2020年 秋学会), 2020.11. |
| 24. |
田中 良昌, 小川 泰信, 門倉 昭, 西山 尚典, 吉川 顕正, Gustavsson Bjorn, Kauristie Kirsti, Enell Carl-fredrik、Brandstrom Urban, Sergienko Tima, Kozlovsky Alexander, Raita Tero, Vanhamaki Heikki, 3D current system of auroral vortices in the discrete arc estimated by auroral tomography and local KRM methods, JpGU-AGU Joint Meeting 2020, 2020.07. |
| 25. |
中溝 葵, 吉川 顕正, 大谷 晋一, 田中 高史, Alfvénic disturbances generated by the ionospheric polarization and the convection reversal in the magnetosphere, JpGU-AGU Joint Meeting 2020, 2020.07. |
| 26. |
吉川 顕正, 中溝 葵, 大谷 晋一, Causality for formation of electromagnetic channel from Polar to Equatorial Ionosphere, JpGU-AGU Joint Meeting 2020, 2020.07. |
| 27. |
Nur Izzati Mohd Rosli, Nurul Shazana Abdul Hamid, Mardina Abdullah、Akimasa Yoshikawa, Teiji Uozumi, Characterization of counter electrojet current according to specific time frame in Southeast Asian sector, JpGU-AGU Joint Meeting 2020, 2020.07. |
| 28. |
藤本 晶子, 吉川 顕正, 池田 昭大, 阿部 修司, 林 萌英, Comparison of FM-CW Ionosonde and MAGDAS observations with S4 index in Peru during 15-18 March 2019, JpGU-AGU Joint Meeting 2020, 2020.07. |
| 29. |
Muhammad Khairul Adib Muhammad Yusof, Mardina Abdullah, Nurul Shazana Abdul Hamid, Suaidi Ahadi, Akimasa Yoshikawa, Correlations of earthquake properties with geomagnetic ULF precursor characteristics over multiple events, JpGU-AGU Joint Meeting 2020, 2020.07. |
| 30. |
藤本 晶子, 阿部 修司, 吉川 顕正, Development of SDR-based scintillation detector system integrated with MAGDAS project, JpGU-AGU Joint Meeting 2020, 2020.07. |
| 31. |
吉川 顕正, 河野 英昭, 阿部 修司, 魚住 禎司, 藤本 晶子, 池田 昭大, 樺澤 大生, 黒木 智, 林 萌英, 高山 久美, 中溝 葵, Ohtani Shinichi, Investigation of global electromagnetic coupling from polar to equatorial ionosphere, JpGU-AGU Joint Meeting 2020, 2020.07. |
| 32. |
Nurul Shazana Abdul Hamid, Wan Nur Izzaty Ismail, Mardina Abdullah、Akimasa Yoshikawa, Teiji Uozumi, Zahira Mohd Razi, Longitudinal Variation and Peak Time of Equatorial Electrojet Current from Ground and Satellite Measurements, JpGU-AGU Joint Meeting 2020, 2020.07. |
| 33. |
樺澤 大生, 吉川 顕正, 魚住 禎司, 藤本 晶子, 阿部 修司, MAGDAS9システムの10Hzデータによる、Pc2脈動の全球的発生分布特性解明, JpGU-AGU Joint Meeting 2020, 2020.07. |
| 34. |
阿部 修司, 藤本 晶子, 魚住 禎司, 吉川 顕正, Recent and future activities of ICSWSE and MAGDAS project, jpGU-AGU Joint Meeting 2020, 2020.07. |
| 35. |
高山 久美, 三好 勉信, 吉川 顕正, Sq・EEJ電流系における6日振動現象に着目した大気圏ー電離圏の上下結合の研究, JpGU-AGU Joint Meeting 2020, 2020.07. |
| 36. |
今城 峻, 能勢 正仁, 相田 真里, 東尾 奈々, 松本 晴久, 古賀 清一, 吉川 顕正, 三好 由純, サブストーム中における近地球磁気圏内での磁場変動の緯度方向分布, JpGU-AGU Joint Meeting 2020, 2020.07. |
| 37. |
山本 衛, 橋口 浩之, 横山 竜宏, 宮岡 宏, 小川 泰信, 塩川 和夫, 野澤 悟, 吉川 顕正, 津田 敏隆, 太陽地球系結合過程の研究基盤形成 ＝計画の現状2020＝, JpGU-AGU Joint Meeting 2020, 2020.07. |
| 38. |
林 萌英, 吉川 顕正, 藤本 晶子, 大谷 晋一, 磁気圏電離圏全球結合系解明に向けたイオノグラムの自動読み取り, JpGU-AGU Joint Meeting 2020, 2020.07. |
| 39. |
Yoshimasa Tanaka, Yasunobu Ogawa, Akira Kadokura, Takanori Nishiyama, Akimasa Yoshikawa, Bjorn Gustavsson, Kirsti Kauristie, Carl-fredrik, Enell, Urban Brandstrom, Tima Sergienko, Alexander Kozlovsky, Tero Raita, Vanhamaki Heikki, Study on auroral 3D structure in the northen Europe, Sixth International Symposium on Arctic Research (ISAR-6), Online, 2020.03. |
| 40. |
Ikeda A., T. Uozumi, A. Yoshikawa, A. Fujimoto, and S. Abe, Diurnal and seasonal variations in the Schumann Resonance observed at Kuju Japan, AGU fall meeting, 2019.12. |
| 41. |
Akiko Fujimoto, Akimasa Yoshikawa, Teiji Uozumi, Shuji Abe, Seasonal dependence of semidiurnal equatorial magnetic variation during quiet and disturbed periods, 10th Anniversary International Conference on Solar-Terrestrial Relations and Physics of Earthquake Precursors, STRPEP 2019, 2019.11, The analysis of 20-year long-term semidiurnal lunar tidal variations gave the evidence that the semidiurnal variations are completely different between the magnetic quiet and disturbed periods. This is the first time that the seasonal dependence of disturbance-time semidiurnal variation has been provided from the analysis of the EE-index. We found the Kp dependence of semidiurnal variation: For full and new moon phase, counter troughs are amplified during disturbance time, possibly related to disturbance dynamo. For all moon phase, there are positive enhancements in dawn and strong depressions after sunset, resulting from the penetration of polar electric filed. For Seasonal dependence, semidiurnal variations are divided to three seasonal groups, and characterized as deep trough, enhanced crest and weak structure for D-solstice, Equinoxes and J-solstice, respectively. There is no significant longitudinal difference between Ancon and Davao, except for the amplitude of semidiurnal variations. The deep troughs occur during D-solstice and the enhanced crests during Equinoxes, at both Ancon and Davao.. |
| 42. |
Wan Nur Izzaty Ismail, Nurul Shazana Abdul Hamid, Mardina Abdullah, Akimasa Yoshikawa, Longitudinal profile of equatorial electrojet derived from ground and satellite based magnetometers, 2018 UKM FST Postgraduate Colloquium, 2019.06, The intense current that flowing eastward in the dayside in the E layer of ionosphere at dip equator region is known as equatorial electrojet (EEJ). In this work, we attempt to compare the longitudinal profile of EEJ current estimated from the Challenging Minisatellite Payload (CHAMP) and European Space Agency satellite (SWARM) with the ground-based magnetometer network from six equatorial observatory pairs across the globe. Ground magnetometer were obtained from the network such as MAGDAS, INTERMAGNET and IIG. We process our data using the EUEL index during quiet days for ground measurement. Then, correlation coefficient were obtained after applying appropriate normalization techniques for both measurements. Analysis showed the longitudinal variations of EEJ current from ground indicates that this current was strongest at South American (77 °W) and Southeast Asian (99.78°E). Meanwhile, satellite measurement shows four peaks of EEJ current at -100°W, 0°E, 100°E and 180° E which are at North America, Atlantic ocean, Southeast Asian and Pacific ocean respectively.. |
| 43. |
Norhani Muhammad Nasir Annadurai, Nurul Shazana Abdul Hamid, Akimasa Yoshikawa, Statistical study of equatorial geomagnetic crochets, 2018 UKM FST Postgraduate Colloquium, 2019.06, This study present the statistical investigation of equatorial geomagnetic crochets due to strong solar flare of class M to X. Our analysis utilized data from eight magnetometer stations provided by MAGnetic Data Acquisition System network (MAGDAS) at different longitudes sector during period from January 2008 to March 2015. We have considered 52 cases of solar flare events. Based on our analysis, 65% of the studied solar flares show no effect on geomagnetic variation with most of it from class M8, M9 and X1. The absence of solar flare effect might due to the influence of coronal mass ejection (CME) on the observation data or due to the station's location is at nighttime. The other 35% shows geomagnetic crochets to the magnetic data variation where majority are mix effect dominated by positive crochets. Apart from that, we also found an interesting solar flare effect where negative geomagnetic crochets were detected from all equatorial magnetometer data. The unique effect is due to X-class solar flare on 9th August 2011. Further investigation using extended latitudinal and longitudinal magnetometer is recommended to observe the whole picture of the solar flare effect to global ionospheric current.. |
| 44. |
Aoi Nakamizo and Akimasa Yoshikawa, Deformation of ionospheric potential pattern by ionospheric Hall polarization, SuperDARN Workshop 2019, Fuji, 2019.06, The present study shows that the ionospheric Hall polarization can deform the high-latitude ionospheric convection field, which is widely considered to be a manifestation of the convection field in the magnetosphere.
We perform the Hall polarization field separation with a potential solver by changing the conductance distribution step- by-step from a uniform one to a more realistic one.
We adopt dawn-dusk and north-south symmetric distributions of conductance and region 1 (R1) field-aligned current (FAC).
The pair of the primary field of the R1 system and each gradient of Hall conductance generates the Hall polarization field and consequently causes potential deformations as follows.
(a) The equatorward gradient causes clockwise rotation.
(b) The gradient across the terminator, together with the effect of the equatorward gradient, causes the dawn-dusk asymmetry.
(c) The high conductance band in the auroral region causes kink-type deformations.
In particular, a nested structure at the equatorward edge of the band in the midnight sector well resembles the Harang Reversal.
Result (a) can explain the clockwise bias inexplicable by the IMF-By effect alone, the combination of (a) and (b) can explain the clearness and unclearness in the round or crescent shapes of the dawn-dusk cells depending on the IMF-By polarity, and (c) suggests that the ionosphere may not need the upward-FAC for the formation of the Harang Reversal.
We suggest that the final structure of the ionospheric potential is established by the combined effects of both the magnetospheric requirements (external causes) and ionospheric polarization (internal effect).. |
| 45. |
Akimasa Yoshikawa, MAGDAS project: Research for global and local electromagnetic coupling from polar to equatorial ionosphere, SuperDARN Workshop 2019, Fuji, 2019.06, International Center for Space Weather Science and Education (ICSWSE) of Kyushu University is a research institute that conducts academic research and education in space weather and related fields. We have constructed an observation network known as the "MAGDAS/CPMN (MAGnetic Data AcquisitionSystem/Circum-pan Pacific Magnetometer Network)" in international collaboration with more than 60 organizations, including those in developing countries. Currently, over 80 magnetometers and 4 FM-CW (Frequency Modulated Continuous Wave) radars have been installed all over the world. To understand the active role of ionospheric dynamics on the global and local Magnetosphere-Ionosphere coupling from polar to equatorial ionosphere, we conduct integrated studies of theory, numerical simulation, in-situ magnetosphere observation, and global ionosphere observation by MAGDAS. Especially, the ionospheric Hall effect strongly controls the spatiotemporal evolution of the M-I coupling system. Generation of polarization electric field at conductance gradient regions causes rotation, shear, and acceleration/deceleration of ionospheric convection in both local and global manners. The ionospheric polarization field activates upward shear Alfven wave that could cause ionospheric driven magnetospheric dynamics and induce a new type of M-I coupled current system. Generation of induction electric field at the wavefront of ionospheric disturbances enables the electric field of electrostatic potential type to propagate horizontally as a result of coupling between magnetosonic mode and shear Alfven mode induced by multistep Hall effect in a time domain, at the ionospheric E-layer. Such a combined effect of ionospheric Hall polarization and induction on the ionospheric dynamics is a key element for understanding the formation process of the global current system from polar to equatorial ionosphere. In this talk, we will discuss how to identify elementary components of Hall-polarization and induction effect (generalized Cowling effect) from coupled phenomena, and the possibility of collaborative studies between SuperDARN and MAGDAS project to further understand active role of ionospheric dynamics.. |
| 46. |
中村勇貴, 寺田綱一郎, 垰千尋, 寺田直樹, 笠羽康正, 北元, 中溝葵, 吉川顕正, 大谷晋一, 土屋史紀, 鍵谷将人, 坂野井健, 村上豪, 吉岡和夫, 木村智樹, 山崎敦, 吉川一朗, Axisymmetric conductivities of Jupiter's middle- and low-latitude ionosphere, 日本地球惑星科学連合2019年大会, 2019.05. |
| 47. |
Akimasa Yoshikawa, Revisiting the energy conversion process of Birkeland current, 日本地球惑星科学連合2019年大会, 2019.05. |
| 48. |
藤本 晶子, 池田 昭大, 吉川顕正, Latest installation of FM-CW radar in Peru, 日本地球惑星科学連合2019年大会, 2019.05. |
| 49. |
樺澤 大生, 吉川 顕正, 魚住 禎司, 藤本 晶子, 阿部 修司, MAGDAS9システムの10Hzデータによる，Pc1-2脈動の全球分布特性解明, 日本地球惑星科学連合2019年大会, 2019.05. |
| 50. |
吉川 顕正, 樺澤 大生, 魚住 禎司, 藤本 晶子, 阿部 修司, Development of MAGDAS project: Search for global electromagnetic coupling from polar to equatorial ionosphere, 日本地球惑星科学連合2019年大会, 2019.05. |
| 51. |
山本 衛, 橋口 浩之, 横山 竜宏, 宮岡 宏, 小川 泰信, 塩川 和夫, 野澤 悟徳, 吉川 顕正, 津田 敏隆, 太陽地球系結合過程の研究基盤形成, 日本地球惑星科学連合2019年大会, 2019.05. |
| 52. |
尾花 由紀, 丸山 奈緒美, 新堀 淳樹, 橋本 久美子, Fedrizzi Mariangel, 能勢 正仁, 大塚 雄一, 西谷 望, 堀 智昭, 熊本 篤志, 土屋 史紀, 松田 昇也, 松岡 彩子, 笠原 禎也, 吉川 顕正, 三好 由純, 篠原 育, An extreme erosion of the plasmasphere during the 7–10 September 2017 storm, 日本地球惑星科学連合2019年大会, 2019.05. |
| 53. |
N. Mohd Anuar, F. A. Mohd Kasran, M. Abbas, M. H. Jusoh, S. A. Enche Ab Rahim, N. Abdul Hadi, Akimasa Yoshikawa, Z. Mohd Radzi, Assessment of the Geomagnetically Induced Current (GIC) at Low Latitude Region based on MAGDAS Data, 1st International Conference on Space Weather and Satellite Application 2018, ICeSSAT 2018, 2019.03, The geomagnetically induced current (GICs) impact is no longer concentrated at high latitude region strictly. The objective of this study was to extend the GICs observation conducted at equatorial region using geomagnetic data extracted from magnetometer installed at Langkawi National Observatory (LNO), Malaysia for the long-term analysis involving the solar cycle 24. The observation is now continued with the GICs comparison between LKW stations with five low latitude station which is BCL, PTN, MND, DAW, and TWV obtained from the magnetic data acquisition system (MAGDAS). The assessment of the GICs behavior revealed the possibility of LKW station experiences GICs is high, based on the time derivative of the horizontal component (dH/dt) value. Extend from that, the GICs estimation was successful done by applying the plane wave method as a model to calculate the North-South and the East-West component, Ex and Ey respectively. The equation of the GICs was provided by excluding the topology constant parameters, which is a and b constant and the value of the underground conductivity for low latitude station. Subsequently, the comparison was limited in years of 2008 - 2014 due to insufficient geomagnetic data. Indeed, the GICs calculation is able to derive the GICs estimation and showed a good agreement with the corresponding value of the time derivative of the horizontal component. However, the accurate current value (A) is able to gain by conducting a direct measurement of the high voltage power transmission system.. |
| 54. |
Siti Nurbaiti Ibrahim, Mohammad Huzaimy Jusoh, Ahmad Asari Sulaiman, Akimasa Yoshikawa, Zahira Mohd Radzi, Characteristic of the Disturbed Days Ionospheric Current System in the 180-Degree Magnetic Meridian, 1st International Conference on Space Weather and Satellite Application 2018, ICeSSAT 2018, 2019.03, The behavior of the ionospheric current during disturbed days using 10 geomagnetic observatories along 180-degree magnetic meridian was analysed. Separation of external and internal current during geomagnetic storm on 12 April until 15 April 2012 data was carried out using spherical harmonic analysis method. The contour of day to day variation of total current, external current and internal current were distinguished based on geomagnetic storm phase. These current then were correlate with the solar wind parameter, IMF Bz, and geomagnetic indices in order to identify their relationship. The results reveal that these current intensities were found higher during the initial phase. This due to the enhancement of the magnetic field during the initial phase caused by the increment of solar wind dynamic pressure and southward IMF Bz. Hence, the induced current identified in the internal current. This study demonstrated that the electric current induction can be obtained from the weak geomagnetic storm.. |
| 55. |
Mio Nakahara, Akimasa Yoshikawa, Teiji Uozumi, Akiko Fujimoto, Electromagnetic induction responses to geomagnetic disturbances at low-and-mid-latitudes, 1st International Conference on Space Weather and Satellite Application 2018, ICeSSAT 2018, 2019.03, The geomagnetically induced current (GIC) is one of the most widely recognized phenomena caused by geomagnetic disturbances. Realistic predictions of magnetic field fluctuations may be used to evaluate the induction of electric fields to ground surfaces, and thus to estimate the occurrence of GICs. Although many GICs occur at high latitudes, they are now being studied at low and mid-latitudes as well. The purpose of this research was to understand the dynamics, observation, and prediction in Japan for GICs occurring at the low and mid-latitudes. In this study, the influence of geomagnetic field variations on Earth's electric field was examined. The magnetic field and the electric field components of 3 observation points for 1 year in 2015 are visually examined, and the characteristics of the fluctuations of the magnetic field and the surface electrical field were also analysed.. |
| 56. |
T. Akiyama, Akimasa Yoshikawa, A. Fujimoto, T. Uozumi, Relationship between plasma bubble and ionospheric current, equatorial electrojet, and equatorial counter electrojet, 1st International Conference on Space Weather and Satellite Application 2018, ICeSSAT 2018, 2019.03, In recent years, it has been clarified from previous studies that plasma bubbles and equatorial electrojets (EEJs) are related. In general, EEJs are calculated by subtracting the magnetic field H component of the magnetic equator from that at low latitude. However, in this study, EE-index data at Langkawi (magnetic equator), which includes all local current systems, were used for the analysis during the period from January 1, 2011, to November 8, 2014. By using the EE-index, it was found that plasma bubbles tend to occur for larger EEJ strengths. This result differs from the previous studies. In addition, if an equatorial counter electrojet (CEJ) occurs, it is understood that plasma bubbles will rarely occur due to the westward current; however, we found that when the lunar tidal effect is strong, plasma bubbles can occur even in conjunction with CEJs. Finally, we want to find the relationship between plasma bubbles and ionospheric current to predict them.. |
| 57. |
Zatul Iffah Abd Latiff, Mohamad Huzaimy Jusoh, Farah Adilah Mohd Kasran, Siti Amalina Enche Ab Rahim, Munirah Onn, Aznilinda Zainuddin, Muhammad Asraf Hairuddin, Nurhani Kasuan, Muhammad Muzamil Mustam, Suhana Mohamed, Akimasa Yoshikawa, The first solar-powered Magdas-9 installation and possible geomagnetically induced currents study at Johor, Malaysia, 1st International Conference on Space Weather and Satellite Application 2018, ICeSSAT 2018, 2019.03, The Magnetic Data Acquisition System (MAGDAS-9) was successfully installed at Universiti Teknologi MARA Johor, Pasir Gudang Campus, Malaysia (JOH station), under the joint collaboration between International Center for Space Weather Science and Education (ICSWSE), National Space Agency (ANGKASA) and UiTM Johor. This is the first solar-powered magnetometer under the Magnetic Data Acquisition System of Circum-pan Pacific Magnetometer Network (MAGDAS/CPMN). In this paper, construction process, installation process and analysis of first geomagnetic observations at MAGDAS JOH station are presented. In addition, analysis on time derivative of horizontal component of geomagnetic field (dH/dt) to indicate the possibility of Geomagnetically Induced Currents (GIC) occurrences is also presented in this paper. The obtained geomagnetic components: H, D, Z and Total F are approximately similar to World Magnetic Model 2015 (WMM2015) while the diurnal variation from this geomagnetic observation showing a good variation pattern. The analysis of dH/dt has indicated 2 significant events of GIC.. |
| 58. |
Nornabilah Mohd Anuar, Farah Adilah Mohd Kasran, Zatul Iffah Abdul Latif, Siti Amalina Ence Ab Rahim, Arif Manut, Mohamad Huzaimy Jusoh, Normi Abdul Hadi, Akimasa Yoshikawa, Estimation of time derivative of horizontal geomagnetic component for GIC assesment in Malaysia during quiet period, 8th International Conference on System Engineering and Technology, ICSET 2018, 2019.01, This paper presents the preliminary observation on the possible Geomagnetic Induced Current (GIC) activities at Malaysia region during the quiet period of solar cycle 24 (year 2017). In fact, the damage of power system operation might lead to the malfunction of the transformer, which is the main component of the power system. Previously, the cause of the damage has been identified in the long-term investigation, where it drives from the space weather effect so-called (GIC). In this work, the quiet period has been selected by respecting the value of K-Planetary index (Kp) must be less than 3 extracted from OMNIWeb data source. The main objective of the current work is to investigate the behavior of the GIC amplitude at Malaysia region as well as to identify the parameter (ionospheric current and magnetospheric current) that contribute significantly towards the GIC activity at Malaysia region. The type of analysis was carried out using the data of geomagnetic field by extracting the time derivative of the horizontal component (dH/dt) as the indicator for GIC activity. The geomagnetic data was obtained from the MAGDAS observatories at Langkawi (LKW), Perak (PER), and Johor (JOH) stations. Subsequently, the dH/dt value is less than 30 nT/min represent no GIC activity occurred during that particular date for all three stations. However, the results revealed that the ionospheric current, DP2 corresponds well to the dH/dt amplitude. Plus, the latitudinal correlation gave the best representation of the control factor of GIC activity.. |
| 59. |
Akimasa YOSHIKAWA, Research of Geomagnetism for Earth and Space Environmen, Theme Seminar of the Scientific lecture at the annual Theme Seminar of the Sri Lanka Association for the Advancement of Science (“Space Science and Technology Applications for Sustainable Development” ), 2018.12. |
| 60. |
Akiko Fujimoto, Akimasa Yoshikawa, Akihiro Ikeda, Global response of Magnetic field and Ionosonde observations to intense solar flares on 6 and 10 September 2017, 9th International Conference "Solar-Terrestrial Relations and Physics of Earthquake Precursors", STRPEP 2018, 2018.11, Intense X-ray fluxes during solar flares are known to cause enhanced ionization in the Earth's ionospheric D, E and F region. This sudden change of ionospheric electron density profile is serious problem to radio wave communication and navigation system. The ground magnetograms often record the sudden change in the sunlit hemisphere during the enhanced X-ray flux, due to the sudden increase in the global ionospheric current system caused by the flare-induced enhanced ionospheric conductivity. These geomagnetic field disturbances are known as "solar flare effects" (SFEs) or geomagnetic crochets [Campbell, 2003]. The typical SFE is increase variation on the equatorial magnetic data. On Ionosonde observation during solar flare event, the High-Frequency (HF) radio wave blackout is often detected in ionogram due to the sudden disturbance in ionosphere. Two intense X-class solar flares occurred on 6 and 10 September 2017. We investigated the magnetic field and Ionosonde responses to the intense solar flare events. Dayside magnetic field variations sudden increased due to the ionospheric disturbance resulting from solar flare. There is no response in night side magnetometer data. The magnitude of SFE (magnetic field) is independent of solar flare X-ray magnitude. We found HF radio wave blackout in ionogram at dayside Ionosonde stations. The duration of blackout is dependent of latitude and local time of Ionosonde stations. There is the different feature of ionogram at night side.. |
| 61. |
Akihiro Ikeda, Teiji Uozumi, Akimasa Yoshikawa, Akiko Fujimoto, Shuji Abe, Schumann resonance parameters at Kuju station during solar flares, 9th International Conference "Solar-Terrestrial Relations and Physics of Earthquake Precursors", STRPEP 2018, 2018.11, We examined the Schumann resonance (SR) at low-latitude station KUJ by comparing with solar X-ray flux and solar proton flux at a geostationary orbit. For intense solar activity in October-November 2003, the reaction of the SR frequency to X-ray enhancement and SPEs was different. The SR frequency in H component increased at the time of the Xray enhancement. The response of SR seems to be caused by the increase of the electron density in the ionospheric D region which ionized by the enhanced solar X-ray flux. In the case of the SPEs, the SR frequency in D component decreased with enhancement of solar proton flux. We suggest that the SPEs caused the decrease of altitude on the ionopheric D region at high-latitude region, and the SR frequency decreased.. |
| 62. |
Akiko Fujimoto, Akimasa Yoshikawa, Akihiro Ikeda, Global response of Magnetic field and Ionosonde observations to intense solar flares on 6 and 10 September 2017, 9th International Conference "Solar-Terrestrial Relations and Physics of Earthquake Precursors", STRPEP 2018, 2018.11, Intense X-ray fluxes during solar flares are known to cause enhanced ionization in the Earth's ionospheric D, E and F region. This sudden change of ionospheric electron density profile is serious problem to radio wave communication and navigation system. The ground magnetograms often record the sudden change in the sunlit hemisphere during the enhanced X-ray flux, due to the sudden increase in the global ionospheric current system caused by the flare-induced enhanced ionospheric conductivity. These geomagnetic field disturbances are known as "solar flare effects" (SFEs) or geomagnetic crochets [Campbell, 2003]. The typical SFE is increase variation on the equatorial magnetic data. On Ionosonde observation during solar flare event, the High-Frequency (HF) radio wave blackout is often detected in ionogram due to the sudden disturbance in ionosphere. Two intense X-class solar flares occurred on 6 and 10 September 2017. We investigated the magnetic field and Ionosonde responses to the intense solar flare events. Dayside magnetic field variations sudden increased due to the ionospheric disturbance resulting from solar flare. There is no response in night side magnetometer data. The magnitude of SFE (magnetic field) is independent of solar flare X-ray magnitude. We found HF radio wave blackout in ionogram at dayside Ionosonde stations. The duration of blackout is dependent of latitude and local time of Ionosonde stations. There is the different feature of ionogram at night side.. |
| 63. |
Akihiro Ikeda, Teiji Uozumi, Akimasa Yoshikawa, Akiko Fujimoto, Shuji Abe, Schumann resonance parameters at Kuju station during solar flares, 9th International Conference "Solar-Terrestrial Relations and Physics of Earthquake Precursors", STRPEP 2018, 2018.11, We examined the Schumann resonance (SR) at low-latitude station KUJ by comparing with solar X-ray flux and solar proton flux at a geostationary orbit. For intense solar activity in October-November 2003, the reaction of the SR frequency to X-ray enhancement and SPEs was different. The SR frequency in H component increased at the time of the Xray enhancement. The response of SR seems to be caused by the increase of the electron density in the ionospheric D region which ionized by the enhanced solar X-ray flux. In the case of the SPEs, the SR frequency in D component decreased with enhancement of solar proton flux. We suggest that the SPEs caused the decrease of altitude on the ionopheric D region at high-latitude region, and the SR frequency decreased.. |
| 64. |
Akimasa YOSHIKAWA, Geomagnetism and Life, Geomagnetic Focus Group Discussion 2018, 2018.09. |
| 65. |
Akimasa YOSHIKAWA, Space Weather Data in IR 4.0 (Industry Revolution 4.0) era and the success story on MAGDAS project, International Conference on Space Weather and Satellite Application (ICeSSAT2018), 2018.08. |
| 66. |
Takafumi Akiyama and Akimasa Yoshikawa, Akiko Fujimoto, Teiji Uozumi, Relationship Between Plasma Bubble and Ionospheric Current Equatorial Electrojet and Equatorial Counter Electrojet, International Conference on Space Weather and Satellite Application (ICeSSAT2018), 2018.08. |
| 67. |
Zatul Iffah Abdul Latiff, Mohamad Huzaimy Jusoh, Aznilinda Zainuddin, Nurhani Kasuan, Munirah Onn Muhammad, Asraf Hairuddin, Suhana Mohamed, Akimasa Yoshikawa, The First Solar-Powered MAGDAS-9 Installation and Possible Geomagnetically Induced Currents Study at Johor, International Conference on Space Weather and Satellite Application (ICeSSAT2018), 2018.08. |
| 68. |
Siti Nurbaiti Ibrahim, Mohamad Huzaimy Jusoh, Ahmad Asari Sulaiman, Akimasa Yoshikawa, Characteristic of the Disturbed Days Ionospheric Current System in the 180-Degree Magnetic Meridian, International Conference on Space Weather and Satellite Application (ICeSSAT2018), 2018.08. |
| 69. |
Akimasa Yoshikawa, On Generalization of Birkeland Current System in the Tree-Dimensional Magnetosphere-Ionosphere Coupling, AOGS2018 15th Annual Meeting, 2018.06. |
| 70. |
Teiji UOZUMI, Akimasa YOSHIKAWA, Shin OHTANI, Dmitry BAISHEV, Alexey MOISEEV, Boris SHEVTSOV, Decomposition of the Wave Elements of the Global High-Correlation Pi 2, AOGS2018 15th Annual Meeting, 2018.06. |
| 71. |
Akiko FUJIMOTO, Akimasa YOSHIKAWA, Toshiya NISHIGUCHI, Local Time Characteristic of Low-Latitude Geomagnetic Field Response to Intense Solar Flares, AOGS2018 15th Annual Meeting, 2018.06. |
| 72. |
Saeed Abioye BELLO, Mardina ABDULLAH, Nurul Shazana ABDUL HAMID, Bodo REINISCH, Akimasa YOSHIKAWA, Equatorial Electrojet and Ionospheric Profile Parameters at Peruvian Station During Solar Minimum, AOGS2018 15th Annual Meeting, 2018.06. |
| 73. |
Akihiro IKEDA, Teiji UOZUMI, Akimasa YOSHIKAWA, Akiko FUJIMOTO, Shuji ABE, Hiromasa NOZAWA, Manabu SHINOHARA, Response of Schumann Resonance to Solar and Geomagnetic Activities, AOGS2018 15th Annual Meeting, 2018.06. |
| 74. |
QZS(みちびき)初号機とMAGDASによる磁気圏FAC‐電離圏電流回路の同時観測に関する統計解析に向けて. |
| 75. |
A Nakamizo, A Yoshikawa, T Tanaka, Effects of Ionospheric Hall Polarization on Magnetospheric Configurations and Dynamics in Global MHD Simulation, AGU Fall Meeting, 2017.12. |
| 76. |
Akihiro Ikeda, Teiji Uozumi, Akimasa Yoshikawa, Akiko Fujimoto, Shuji Abe, Hiromasa Nozawa, Manabu Shinohara, Characteristics of Schumann Resonance Parameters at Kuju Station, 8th International Conference on Solar-Terrestrial Relations and Physics of Earthquake Precursors, STREEP 2017, 2017.10, The ground magnetic field variation in the extremely low frequency (ELF) range has been measured by an induction magnetometer at Kuju, Japan (KUJ; M.Lat. = 23.4 degrees, M. Lon. = 201.0 degrees) since 2003. The first mode of the Schumann resonance (SR) around 8 Hz can be seen at KUJ. The SR in H (horizontal northward component) shows maximum peaks around 08 UT and 15 UT. In the case of D (horizontal eastward component), the SR shows its maximum peak around 08 UT. These peaks are coincident with the enhancement of lightning activity in Africa and Asia. Thus, we found the influence of the lightning activity on the observed SR at KUJ.. |
| 77. |
Akimasa Yoshikawa, Akiko Fujimoto, Akihiro Ikeda, Teiji Uozumi, Shuji Abe, Monitoring of Space and Earth electromagnetic environment by MAGDAS project
Collaboration with IKIR-Introduction to ICSWSE/MAGDAS project, 8th International Conference on Solar-Terrestrial Relations and Physics of Earthquake Precursors, STREEP 2017, 2017.10, For study of coupling processes in the Solar-Terrestrial System, International Center for Space Weather Science and Education (ICSWSE), Kyushu University has developed a real time magnetic data acquisition system (the MAGDAS project) around the world. The number of observational sites is increasing every year with the collaboration of host countries. Now at this time, the MAGDAS Project has installed 78 real time magnetometers-so it is the largest magnetometer array in the world. The history of global observation at Kyushu University is over 30 years and number of developed observational sites is over 140. Especially, Collaboration between IKIR is extended back to 1990's. Now a time, we are operating Flux-gate magnetometer and FM-CW Radar. It is one of most important collaboration for space weather monitoring. By using MAGDAS data, ICSWSE produces many types of space weather index, such as EE-index (for monitoring long tern and shot term variation of equatorial electrojet), Pc5 index (for monitoring solar-wind velocity and high energy electron flux), Sq-index (for monitoring global change of ionospheric low and middle latitudinal current system), and Pc3 index (for monitoring of plasma density variation at low latitudes). In this report, we will introduce recent development of MAGDAS/ICSWSE Indexes project and topics for new open policy for MAGDAS data will be also discussed.. |
| 78. |
Akihiro Ikeda, Teiji Uozumi, Akimasa Yoshikawa, Akiko Fujimoto, Shuji Abe, Hiromasa Nozawa, Manabu Shinohara, Characteristics of Schumann Resonance Parameters at Kuju Station, 8th International Conference on Solar-Terrestrial Relations and Physics of Earthquake Precursors, STREEP 2017, 2017.10, The ground magnetic field variation in the extremely low frequency (ELF) range has been measured by an induction magnetometer at Kuju, Japan (KUJ; M.Lat. = 23.4 degrees, M. Lon. = 201.0 degrees) since 2003. The first mode of the Schumann resonance (SR) around 8 Hz can be seen at KUJ. The SR in H (horizontal northward component) shows maximum peaks around 08 UT and 15 UT. In the case of D (horizontal eastward component), the SR shows its maximum peak around 08 UT. These peaks are coincident with the enhancement of lightning activity in Africa and Asia. Thus, we found the influence of the lightning activity on the observed SR at KUJ.. |
| 79. |
Akimasa Yoshikawa, Akiko Fujimoto, Akihiro Ikeda, Teiji Uozumi, Shuji Abe, Monitoring of Space and Earth electromagnetic environment by MAGDAS project Collaboration with IKIR-Introduction to ICSWSE/MAGDAS project, 8th International Conference on Solar-Terrestrial Relations and Physics of Earthquake Precursors, STREEP 2017, 2017.10, For study of coupling processes in the Solar-Terrestrial System, International Center for Space Weather Science and Education (ICSWSE), Kyushu University has developed a real time magnetic data acquisition system (the MAGDAS project) around the world. The number of observational sites is increasing every year with the collaboration of host countries. Now at this time, the MAGDAS Project has installed 78 real time magnetometers-so it is the largest magnetometer array in the world. The history of global observation at Kyushu University is over 30 years and number of developed observational sites is over 140. Especially, Collaboration between IKIR is extended back to 1990's. Now a time, we are operating Flux-gate magnetometer and FM-CW Radar. It is one of most important collaboration for space weather monitoring. By using MAGDAS data, ICSWSE produces many types of space weather index, such as EE-index (for monitoring long tern and shot term variation of equatorial electrojet), Pc5 index (for monitoring solar-wind velocity and high energy electron flux), Sq-index (for monitoring global change of ionospheric low and middle latitudinal current system), and Pc3 index (for monitoring of plasma density variation at low latitudes). In this report, we will introduce recent development of MAGDAS/ICSWSE Indexes project and topics for new open policy for MAGDAS data will be also discussed.. |
| 80. |
Yoshikawa A., Monitoring of Space and Earth electromagnetic environment by MAGDAS project: Collaboration with IKIR, International Conference on Solar-Terrestrial Relations and Physics of Earthquake Precursors, 2017.09. |
| 81. |
Akihiro Ikeda, Teiji Uozumi, Akimasa Yoshikawa, Akiko Fujimoto, Shuji Abe, Hiromasa Nozawa, Manabu Shinohara, Characteristics of Schumann Resonance Parameters at Kuju Station, International Conference on Solar-Terrestrial Relations and Physics of Earthquake Precursors, 2017.09. |
| 82. |
Yoshikawa A., Study of Coupling Processes in the Solar-Terrestrial System, 2nd National School on EARTH and ELECTROMAGNETISM, 2017.08. |
| 83. |
Yoshikawa A., Geomagnetic observation to support space weather study, AMGASA Public Talk, 2017.08, 汎世界的な地磁気多点観測網によりあぶり出される様々な宇宙天気現象、宇宙ー気象ー地象結合現象について紹介し、その適用サイエンスの幅広さと様々な地球物理現象のモニタリングの可能性について、わかりやすく講演する。. |
| 84. |
Yoshikawa A., What is Space Weather?, Universidad Nacional Agraria de la Selva (UNAS) Invited Seminar, 2017.08. |
| 85. |
W. N.I. Ismail, N. S.A. Hamid, M. Abdullah, Akimasa Yoshikawa, T. Uozumi, Longitudinal Variation of EEJ Current during Different Phases of Solar Cycle, 2017 International Conference on Space Science and Communication: Space Science for Sustainability, IconSpace 2017, 2017.06, The equatorial electrojet (EEJ) is an eastward current flow around the dip equator in E-region of the ionosphere within the range of 90 to 120 km altitude. The longitudinal variation of EEJ was studied using the ground-based measurement from six different longitudinal sectors. The ground magnetometer data were provided by magnetometer networks such as those from Magnetic Data Acquisition System (MAGDAS) /Circum-pan Pacific Magnetometer Network (CPMN), Indian Institute of Geomagnetism (IIG) and International Real-time Magnetic Observatory Network (INTERMAGNET). The EUEL index used in this study was calculated from geomagnetic northward H component. The H-component was normalized to the dip equator using the CM4 model. This study present results of the longitudinal variation of EEJ during the three phases of solar cycle 24: solar minimum (2008), inclination phase (2011) and solar maximum (2014). Results show that EEJ current is higher in the American sector and lowest between African and Indian sector in 2008 and 2011. On the other hand, during the year of solar maximum, this current component is comparable in American and Southeast Asian sector.. |
| 86. |
N. S.A. Hamid, Huixin Liu, T. Uozumi, Akimasa Yoshikawa, N. M.N. Annadurai, Peak time of equatorial electrojet from different longitude sectors during fall solar minimum, 2017 International Conference on Space Science and Communication: Space Science for Sustainability, IconSpace 2017, 2017.06, Equatorial electrojet is an eastward flowing current at about ±3° dip equator. This current intensity is always higher during noontime as it is greatly influenced by the ionization of Earth ionosphere. Apart from that, previous study had shown that EEJ current varies with longitude and latitude as well as solar cycle. The aim of this study is to investigate the peak time of EEJ current at different longitude sectors using simultaneous data in 2009. By eliminating Sq current contribution and normalizing ground-based data from MAGDAS/CPMN, IIG and WDC network, we managed to reach our purpose and gain reliable output. We found out that EEJ is strongest in South American sector. Our results show that the peak EEJ during fall solar minimum is observed at 11 LT for South American, Indian and Southeast Asian sector but it is 1 hr earlier in African sector.. |
| 87. |
W. N.I. Ismail, N. S.A. Hamid, M. Abdullah, A. Yoshikawa, T. Uozumi, Longitudinal Variation of EEJ Current during Different Phases of Solar Cycle, 2017 International Conference on Space Science and Communication: Space Science for Sustainability, IconSpace 2017, 2017.06, The equatorial electrojet (EEJ) is an eastward current flow around the dip equator in E-region of the ionosphere within the range of 90 to 120 km altitude. The longitudinal variation of EEJ was studied using the ground-based measurement from six different longitudinal sectors. The ground magnetometer data were provided by magnetometer networks such as those from Magnetic Data Acquisition System (MAGDAS) /Circum-pan Pacific Magnetometer Network (CPMN), Indian Institute of Geomagnetism (IIG) and International Real-time Magnetic Observatory Network (INTERMAGNET). The EUEL index used in this study was calculated from geomagnetic northward H component. The H-component was normalized to the dip equator using the CM4 model. This study present results of the longitudinal variation of EEJ during the three phases of solar cycle 24: solar minimum (2008), inclination phase (2011) and solar maximum (2014). Results show that EEJ current is higher in the American sector and lowest between African and Indian sector in 2008 and 2011. On the other hand, during the year of solar maximum, this current component is comparable in American and Southeast Asian sector.. |
| 88. |
N. S.A. Hamid, H. Liu, T. Uozumi, A. Yoshikawa, N. M.N. Annadurai, Peak time of equatorial electrojet from different longitude sectors during fall solar minimum, 2017 International Conference on Space Science and Communication: Space Science for Sustainability, IconSpace 2017, 2017.06, Equatorial electrojet is an eastward flowing current at about ±3° dip equator. This current intensity is always higher during noontime as it is greatly influenced by the ionization of Earth ionosphere. Apart from that, previous study had shown that EEJ current varies with longitude and latitude as well as solar cycle. The aim of this study is to investigate the peak time of EEJ current at different longitude sectors using simultaneous data in 2009. By eliminating Sq current contribution and normalizing ground-based data from MAGDAS/CPMN, IIG and WDC network, we managed to reach our purpose and gain reliable output. We found out that EEJ is strongest in South American sector. Our results show that the peak EEJ during fall solar minimum is observed at 11 LT for South American, Indian and Southeast Asian sector but it is 1 hr earlier in African sector.. |
| 89. |
Yoshikawa A., Recent Development of ICWSE/MAGDAS project for Study of Coupling Processes in the Solar-Terrestrial System, 日本地球惑星科学連合2017大会, 2017.05. |
| 90. |
Yoshikawa A., Magnetosphere-Ionosphere coupling process produced by Ampere force forcing from the magnetosphere, 日本地球惑星科学連合2017大会, 2017.05. |
| 91. |
藤本 晶子, 吉川 顕正, 魚住 禎司, 阿部 修司, 松下 拓輝, MAGDASプロジェクトEE-indexの磁気赤道域現象への適用事例, 日本地球惑星科学連合2017大会, 2017.05. |
| 92. |
Teiji Uozumi, Akimasa Yoshikawa, Shinichi Ohtani, D G Baishev, A V Moiseyev, B M Shevtsov, Decomposition of the wave elements of the global high-correlation Pi 2, 日本地球惑星科学連合2017大会, 2017.05. |
| 93. |
中溝 葵, 吉川 顕正, 田中 高史, Study on Effects of Ionospheric Polarization Field and Inner Boundary Conditions on Magnetospheric Dynamics and Substorm Processes in Global MHD Simulation, 日本地球惑星科学連合2017大会, 2017.05. |
| 94. |
今城 峻, 吉川 顕正, 魚住 禎司, 大谷 晋一, 中溝 葵, Application of Global Three-Dimensional Current Model for Dayside and Terminator Pi2 Pulsations, 日本地球惑星科学連合2017大会, 2017.05. |
| 95. |
秋山 鷹史, 吉川 顕正, 松下 拓輝, 藤本 晶子, 魚住 禎司, On the relationships between EEJ distribution and plasma bubble occurrences, 日本地球惑星科学連合2017大会, 2017.05. |
| 96. |
中原 美音, 松下 拓輝, 吉川 顕正, 魚住 禎司, 藤本 晶子, 阿部 修司, 磁気擾乱時における中低緯度領域電磁誘導応答の研究, 日本地球惑星科学連合2017大会, 2017.05. |
| 97. |
阿部 修司, 花田 俊也, 吉川 顕正, 平井 隆之, 河本 聡美, スペースデブリ環境推移モデルにおける大気密度モデルの改良と宇宙天気活動の影響評価, 日本地球惑星科学連合2017大会, 2017.05. |
| 98. |
津田 敏隆, 山本 衛, 橋口 浩之, 宮岡 宏, 小川 泰信, 塩川 和夫, 野澤 悟徳, 吉川 顕正, Study of the Coupled Solar-Earth System with Large Atmospheric Radars, Ground-based Observation Network and Satellite Data: Project Overview, 日本地球惑星科学連合2017大会, 2017.05. |
| 99. |
池田 昭大, 魚住 禎司, 吉川 顕正, 藤本 晶子, 阿部 修司, 野澤 宏大, 久住におけるシューマン共鳴の長期変動, 日本地球惑星科学連合2017大会, 2017.05. |
| 100. |
新堀 淳樹, 菊池 崇, 荒木 徹, 池田 昭大, 魚住 禎司, 歌田 久司, 長妻 努, 吉川 顕正, Local time and seasonal variations of the amplitude of the main impulse (MI) of geomagnetic sudden commencements in the low-latitude and equatorial regions, 日本地球惑星科学連合2017大会, 2017.05. |
| 101. |
寺田 綱一朗、垰 千尋、土屋 史紀、笠羽 康正、北 元、中溝 葵、吉川 顕正、大谷 晋一、土屋 史紀、鍵谷 将人、坂野井 健、村上 豪、吉岡 和夫、木村 智樹、山崎 敦、吉川 一朗, 電離圏ポテンシャルソルバーによる木星内部磁気圏電場の太陽風応答の研究, 日本地球惑星科学連合2017大会, 2017.05. |
| 102. |
Nurul Shazana Abdul Hamid, Saeed Abioye Bello, Mardina Abdullah, Akimasa Yoshikawa, The Sq-current and the Ionospheric Profile Parameters during Solar Minimum, 日本地球惑星科学連合2017大会, 2017.05. |
| 103. |
Nurul Shazana Abdul Hamid, Wan Nur Izzaty Ismail, Mardina Abdullah, Akimasa Yoshikawa, Latitudinal and Longitudinal Profile of EEJ current during different phases of Solar Cycle, 日本地球惑星科学連合2017大会, 2017.05. |
| 104. |
Quirino Sugon Jr., Christine Chan, Felix Muga II, Clint Bennett, Randell Teodoro, Sergio Su, Daniel McNamara, Dexter Lo, Roland Otadoy, Grace Rolusta, Akiko Fujimoto, Teiji Uozumi, and Akimasa Yoshikawa, Co-seismic magnetic signatures of Moro Gulf Quake of 2010-07-23 using MAGDAS data, 地域ネットワークによる宇宙天気の観測・教育活動に関する研究集会, 2017.03. |
| 105. |
Quirino Sugon Jr., Christine Chan, Clint Bennett, Felix Muga II, Daniel McNamara, Roland Otadoy, Akiko Fujimoto, Teiji Uozumi, and Akimasa Yoshikawa, MAGDAS measurement of EEJ height incorporating lithosperic image currents in dielectric ground, シンポジウム「太陽地球系科学に於ける地上観測の現状と課題」, 2017.03. |
| 106. |
長期の宇宙天気活動に伴うスペースデブリ環境の推移予測. |
| 107. |
QZSとMAGDAS地上磁力計による磁気圏FAC‐電離層電流回路の同時観測:初期統計解析. |
| 108. |
Yoshikawa A., A. Nakamizo, and S. Ohtani, Generalized Description of Three- Dimensional Magnetosphere-Ionosphere Coupling by Shear Alfvén Waves, 2016 Fall AGU Meeting, 2016.12. |
| 109. |
Ohtani, S., and A. Yoshikawa, Field-aligned Currents Induced by Electrostatic Polarization at the Ionosphere: Application to the Poleward Boundary Intensification (PBI) of Auroral Emission, 2016 Fall AGU Meeting, 2016.12. |
| 110. |
A. Nakamizo and A. Yoshikawa, Possibility of Ionospheric Cause of FACs and Convection Field in the Magnetosphere-Ionosphere System: The Harang Reversal, Premidnight Upward-FAC, and the Ionospheric Hall Polarization Field, 2016 Fall AGU Meeting, 2016.12. |
| 111. |
Matsushita, H., A. Yoshikawa, T. Uozumi, A. Fujimoto, S. Abe, J. K. Ishitsuka, O. Veliz, D. Rosales, E. Safor and V. Beteta, Development of EEJ Model Based on Dense Ground-based Magnetometer Array, 2016 Fall AGU Meeting, 2016.12. |
| 112. |
＠Yoshikawa A., Magnetosphere-Ionosphere Coupling, The SCOSTEP/ISWI International School on Space Science, 2016.11. |
| 113. |
阿部修司, 花田俊也, 吉川顕正, 平井隆之, 河本聡美, 宇宙天気に伴うスペースデブリ環境推移の長期変動と予測, 第3回「太陽地球環境データ解析に基づく超高層大気の空間・時間変動の解明」, 2016.10. |
| 114. |
阿部修司, 花田俊也, 吉川顕正, 平井隆之, 河本聡美, 長期の宇宙天気活動に伴うスペースデブリ環境の推移予測, 第7回スペースデブリワークショップ, 2016.10. |
| 115. |
阿部修司, 花田俊也, 吉川顕正, 平井隆之, 河本聡美, 宇宙天気活動に伴うスペースデブリ環境の変動と予測, 第60回宇宙科学技術連合講演会, 2016.09. |
| 116. |
花田 俊也, 阿部 修司, 吉川 顕正, 藤田 浩輝, スペースデブリ環境の理解に向けて, 宇宙科学技術連合講演会講演集, 2016.09. |
| 117. |
Geospace Disturbances and Geomagentically Induced Current. |
| 118. |
Yoshikawa A., (B,V) Paradigm of Magnetosphere-Ionosphere Coupling, URSI Asia-Pacific Radio Science Conference (URSI AP-RASC 2016), 2016.08, これまでの磁気圏電離圏結合研究では、磁気圏側はMHDダイナミクス（B-Vパラダイム）で、電離圏側は静電的な電離層電流層近似（J-Eパラダイム）で扱われ、その両者は静電的な境界条件をつうじた結合問題として扱われてきた。本研究では電離圏ダイナミクスをイオン-中性大気の衝突効果により必然的に生じるHall電場を電離圏から磁気圏までシームレスに導入する理論的枠組を整理し、磁気圏電離圏結合系を一つの系のダイナミクスの下に記述する(B,V)パラダイムを提案する。これにより、これまで電気回路的な理解しかされてこなかった電離圏特有の現象をプラズマダイナミクスの文脈の下に記述することが可能となる。. |
| 119. |
Impact of Space Weather on Earth COSPAR Capacity Building Workshop, Magnetosphere-Ionosphere coupling by shear Alfven wave, August 15 – 26, 2016, 2016.08. |
| 120. |
Yoshikawa A., Fujimoto, A., T. Uozumi, S. Abe, H. Matsushita, and, S. Abe, Space Weather Indexes Produced by ICSWSE/MAGDAS Project, Asia Oceania Geoscience Society 13th Annual Meeting, 2016.07. |
| 121. |
Matsushita, H., A. Yoshikawa, T. Uozumi, A. Fujimoto, S. Abe, J. K. Ishitsuka, O. Veliz, D. ROSALES, E. SAFOR, V. BETETA, and G. CÁRDENAS, Development Of New Eej Index By Dense Magnetometer Array In Peru, presented at Asia Oceania Geoscience Society 13th Annual Meeting, Asia Oceania Geoscience Society 13th Annual Meeting, 2016.07. |
| 122. |
Fujimoto, A., T. Uozumi, S. Abe, H. Matsushita, and A. Yoshikawa, Long-term EE-index Variation for Monitoring Equatorial Electrojet Based on ICSWSE Magnetometer Network, Asia Oceania Geoscience Society 13th Annual Meeting, 2016.07. |
| 123. |
Abe. S, H. Matsushita, Y. Nawata, A. Yoshikawa, Three components analysis of ground magnetometer network data for developing GIC index,13th Annual Meeting Asia Oceania Geoscience Society, Asia Oceania Geoscience Society 13th Annual Meeting, 2016.07. |
| 124. |
Yoshikawa A., How much curl-free Hall current flows out to the magnetosphere as field-aligned current from Cowling channel?, Chamman Conference on Current in Geospace and Beyond, 2016.05. |
| 125. |
Yoshikawa A., Shuji Abe, Teiji Uozumi, Akiko Fujimoto, Hiroki Matsushita, Hideaki Kawano, Recent development of MAGDAS project: Strategy for international alliance of geomagnetic field network observation, 日本地球惑星科学連合2016大会, 2016.05. |
| 126. |
Nakamizo, A. and A. Yoshikawa, The Harang Reversal Generated by Ionospheric Polarization Field by Hall Current Divergence, 日本地球惑星科学連合2016大会, 2016.05. |
| 127. |
Ohtani, S., and A. Yoshikawa, What if the evolution of auroral forms does not reflect magnetospheric processes?, 日本地球惑星科学連合2016大会, 2016.05. |
| 128. |
Chiharu Shimizu, Mitsuteru Sato, Yukihiro Takahashi, Fuminori Tsuchiya, Yasuji Hongo, Shuji Abe, Akimasa Yoshikawa, Relation between charge amounts of lightning discharges derived from ELF waveform data and severe weather, 日本地球惑星科学連合2016大会, 2016.05. |
| 129. |
寺田綱一朗, 寺田直樹, 笠羽康正, 北, 垰千尋, 中溝葵, 吉川顕正, 大谷晋一, 土屋史紀, 鍵谷将人, 坂野井健, 村上豪, 吉岡和夫, 木村智樹, 山崎敦, 吉川一朗, 電離圏ポテンシャルソルバーによる木星内部磁気圏電場の太陽風応答の研究 discharges derived from ELF waveform data and severe weather, 日本地球惑星科学連合2016大会, 2016.05. |
| 130. |
安宅 祐香, 石坂 圭吾, 阿部 琢美, 田中 真, 熊本 篤志, 吉川 顕正, 松下 拓輝, Sq電流系中心の電子加熱現象解明のための観測ロケット実験速報-DC電場&超低周波波動観測-, 日本地球惑星科学連合2016大会, 2016.05. |
| 131. |
阿部琢美, 石坂圭吾, 熊本篤志, 田中真, 高橋隆男, 松下拓輝, 吉川顕正, Sq電流系中心の電子加熱現象解明のための観測ロケット実験速報－電子エネルギー分布観測－, 日本地球惑星科学連合2016大会, 2016.05. |
| 132. |
尾上彩希子, 河野英昭, 魚住禎司, Shevtsov Boris, Khomutov Sergey, Poddelskiy Igor, Marshall Richard, 吉川顕正, MAGDAS/CPMN group, 日本経度帯のプラズマ圏密度季節変化：北半球、南半球各々でのMAGDAS磁場観測からの推定・比較, 日本地球惑星科学連合2016大会, 2016.05. |
| 133. |
Abe. S, H. Matsushita, Y. Nawata, A. Yoshikawa, Three components analysis of ground magnetometer network data for understanding GIC excited by space weather disturbances, 日本地球惑星科学連合2016大会, 2016.05. |
| 134. |
Matsushita, H, A. Yoshikawa, T. Uozumi, J. Ishitsuka, D. Rosales, O. Veliz, V. B. Alvarado and G. M. Cárdenas, Development of dense magnetometer array in Peru for investigating detailed structure of EEJ, 1st PSTEP International Symposium, 2016.01. |
| 135. |
Fujimoto, A., A. Yoshikawa, T. Uozumi, S. Abe, and H. Matsushita, Space weather environment index based on ICSWSE magnetometer network, 1st PSTEP International Symposium, 2016.01. |
| 136. |
Yoshikawa A., Time-dependent generalized Ohm’s Law and formation of global Cowling channel in the ionosphere, 14th International Symposium on Equatorial Aeronomy (ISEA), 2015.10. |
| 137. |
Babatunde Rabiu, O.O.Folarin, T. Uozumi, N.S.Abdul-Hamid, A.Yoshikawa, Longitudinal variation of Equatorial Electrojet and the Occurrence of its Counter Electrojet, 14th International Symposium on Equatorial Aeronomy (ISEA), 2015.10. |
| 138. |
Innovative Globalization of Space Weather Science and Education Based on International Observation Network. |
| 139. |
N. S.A. Hamid, Huixin Liu, T. Uozumi, G. K. Gopir, H. A. Hadin, Akimasa Yoshikawa, Longitudinal and solar activity dependence of equatorial electrojet at Southeast Asian sector, 4th International Conference on Space Science and Communication, IconSpace 2015, 2015.09, In the E layer of equatorial ionosphere, the equatorial electrojet (EEJ) current interacts with the global Sq current and caused abnormally large amplitude of geomagnetic field component measured at the magnetic dip equator station. In this study, we attempted to separate EEJ and Sq at dip equator using the EUEL index derived from MAGDAS/CPMN stations. Moreover, we normalized the observation data to overcome the uncertainties due to the latitudinal variation of both EEJ and Sq currents which are neglected in most of previous studies. This new approach allowed the study of longitudinal dependence of EEJ. Analysis is performed using data from stations at East and West of Southeast Asian sector for a year of 2011. Additionally, we examined the solar activity dependence of EEJ during this inclining phase of solar cycle.. |
| 140. |
S. N.A. Ahmad, M. H. Jusoh, F. A.M. Kasran, M. Abdullah, B. Veenadhari, T. Uozumi, S. Abe, Akimasa Yoshikawa, M. G. Cardinal, Variations of ULF and VLF during moderate geomagnetic storm at equatorial region, 4th International Conference on Space Science and Communication, IconSpace 2015, 2015.09, This paper presents variations of Ultra Low Frequency (ULF) and Very Low Frequency (VLF) during moderate geomagnetic storm using ground based observatories, Magnetic Data Acquisition System (MAGDAS)/Circum-Pan Magnetic Network (CPMN) magnetometer and Atmospheric Weather Electromagnetic System for Observation Modeling and Education (AWESOME) VLF receiver. In this analysis, the recorded ULF horizontal (H)-component are extracted from MAGDAS magnetometer at Yap Island (YAP), Federated States of Micronesia, Davao (DAV), Philippines, and Tirunelveli (TIR), India stations. VLF amplitude data were observed from VLF receiver at UKM while the transmitters are located at Katabomman (VTX), India, North West Cape (NWC), Australia and Lualualei, Hawaii (NPM), USA. The observations of the space weather conditions in this study are divided into two categories: quiet day (10 April 2010) and moderate geomagnetic storm (6 April 2010). The results show that the ULF and VLF variations are significantly affected during geomagnetic storm which geomagnetic activities are closely related with the solar parameters.. |
| 141. |
Yoshikawa A., MAGDAS Network, Space Weather, and Geomagnetic Storms, A Conference on “Scientific Frontiers: Serving the Peripheries in Times of Change”, 2015.09. |
| 142. |
Yoshikawa A., Description of Magnetosphere-ionosphere coupling with Alfven waves, Olaf Amm Memorial Workshop, 2015.09. |
| 143. |
Yoshikawa A., The Magnetosphere-Ionosphere Coupling, International School on Equatorial and Low-Latitude Ionosphere, ISELLI, 2015.09. |
| 144. |
N. S.A. Hamid, Huixin Liu, T. Uozumi, G. K. Gopir, H. A. Hadin, Akimasa Yoshikawa, Longitudinal and solar activity dependence of equatorial electrojet at Southeast Asian sector, 4th International Conference on Space Science and Communication, IconSpace 2015, 2015.09, In the E layer of equatorial ionosphere, the equatorial electrojet (EEJ) current interacts with the global Sq current and caused abnormally large amplitude of geomagnetic field component measured at the magnetic dip equator station. In this study, we attempted to separate EEJ and Sq at dip equator using the EUEL index derived from MAGDAS/CPMN stations. Moreover, we normalized the observation data to overcome the uncertainties due to the latitudinal variation of both EEJ and Sq currents which are neglected in most of previous studies. This new approach allowed the study of longitudinal dependence of EEJ. Analysis is performed using data from stations at East and West of Southeast Asian sector for a year of 2011. Additionally, we examined the solar activity dependence of EEJ during this inclining phase of solar cycle.. |
| 145. |
S. N.A. Ahmad, M. H. Jusoh, F. A.M. Kasran, M. Abdullah, B. Veenadhari, T. Uozumi, S. Abe, Akimasa Yoshikawa, M. G. Cardinal, Variations of ULF and VLF during moderate geomagnetic storm at equatorial region, 4th International Conference on Space Science and Communication, IconSpace 2015, 2015.09, This paper presents variations of Ultra Low Frequency (ULF) and Very Low Frequency (VLF) during moderate geomagnetic storm using ground based observatories, Magnetic Data Acquisition System (MAGDAS)/Circum-Pan Magnetic Network (CPMN) magnetometer and Atmospheric Weather Electromagnetic System for Observation Modeling and Education (AWESOME) VLF receiver. In this analysis, the recorded ULF horizontal (H)-component are extracted from MAGDAS magnetometer at Yap Island (YAP), Federated States of Micronesia, Davao (DAV), Philippines, and Tirunelveli (TIR), India stations. VLF amplitude data were observed from VLF receiver at UKM while the transmitters are located at Katabomman (VTX), India, North West Cape (NWC), Australia and Lualualei, Hawaii (NPM), USA. The observations of the space weather conditions in this study are divided into two categories: quiet day (10 April 2010) and moderate geomagnetic storm (6 April 2010). The results show that the ULF and VLF variations are significantly affected during geomagnetic storm which geomagnetic activities are closely related with the solar parameters.. |
| 146. |
N. S.A. Hamid, H. Liu, T. Uozumi, G. K. Gopir, H. A. Hadin, A. Yoshikawa, Longitudinal and solar activity dependence of equatorial electrojet at Southeast Asian sector, 4th International Conference on Space Science and Communication, IconSpace 2015, 2015.09, In the E layer of equatorial ionosphere, the equatorial electrojet (EEJ) current interacts with the global Sq current and caused abnormally large amplitude of geomagnetic field component measured at the magnetic dip equator station. In this study, we attempted to separate EEJ and Sq at dip equator using the EUEL index derived from MAGDAS/CPMN stations. Moreover, we normalized the observation data to overcome the uncertainties due to the latitudinal variation of both EEJ and Sq currents which are neglected in most of previous studies. This new approach allowed the study of longitudinal dependence of EEJ. Analysis is performed using data from stations at East and West of Southeast Asian sector for a year of 2011. Additionally, we examined the solar activity dependence of EEJ during this inclining phase of solar cycle.. |
| 147. |
S. N.A. Ahmad, M. H. Jusoh, F. A.M. Kasran, M. Abdullah, B. Veenadhari, T. Uozumi, S. Abe, A. Yoshikawa, M. G. Cardinal, Variations of ULF and VLF during moderate geomagnetic storm at equatorial region, 4th International Conference on Space Science and Communication, IconSpace 2015, 2015.09, This paper presents variations of Ultra Low Frequency (ULF) and Very Low Frequency (VLF) during moderate geomagnetic storm using ground based observatories, Magnetic Data Acquisition System (MAGDAS)/Circum-Pan Magnetic Network (CPMN) magnetometer and Atmospheric Weather Electromagnetic System for Observation Modeling and Education (AWESOME) VLF receiver. In this analysis, the recorded ULF horizontal (H)-component are extracted from MAGDAS magnetometer at Yap Island (YAP), Federated States of Micronesia, Davao (DAV), Philippines, and Tirunelveli (TIR), India stations. VLF amplitude data were observed from VLF receiver at UKM while the transmitters are located at Katabomman (VTX), India, North West Cape (NWC), Australia and Lualualei, Hawaii (NPM), USA. The observations of the space weather conditions in this study are divided into two categories: quiet day (10 April 2010) and moderate geomagnetic storm (6 April 2010). The results show that the ULF and VLF variations are significantly affected during geomagnetic storm which geomagnetic activities are closely related with the solar parameters.. |
| 148. |
Imajo S., A. Yoshikawa, T. Uozumi, S. Ohtani, A. Nakamizo, P. J. Chi, Nature of dayside ionospheric current system of Pi2 Pulsations: Comparison between equivalent currents and numerical simulation, AOGS12th Annual Meeting, 2015.08. |
| 149. |
Gopalswamy Nat, 吉川 顕正, 国際宇宙天気イニシアチブ プロジェクト（ISWI）, 日本地球惑星科学連合2015年大会, 2015.05. |
| 150. |
CHI, Peter, YOSHIKAWA, Akimasa, MANN, Ian, International collaboration in ground based magnetometer observations via ULTIMA: A tribute to Professor Kiyohumi Yumoto, 日本地球惑星科学連合2015年大会, 2015.05. |
| 151. |
BAISHEV, Dmitry, MULLAYAROV, Victor SAMSONOV, Sergey MISHIN, Vladimir, UOZUMI, Teiji, YOSHIKAWA, Akimasa, KOGA, Kiyokazu, MATSUMOTO, Haruhisa, Generation of geomagnetic Pc5 pulsations by compressional waves penetrating from the solar wind: a case study, 日本地球惑星科学連合2015年大会, 2015.05. |
| 152. |
H. Matsushita, Akimasa Yoshikawa, The features of vertical component of daily geomagnetic field during geomagnetic storm, United Nations/Japan for Space Weather Symposium, 2015.03. |
| 153. |
Akimasa Yoshikawa, ICSWSE/MAGDAS project, United Nations/Japan for Space Weather Symposium, 2015.03. |
| 154. |
Estelle, Dirand, Akimasa Yoshikawa, Computer simulation on formation of ionospheric current system accompanied by the incidence of shear Alfvén waves to the ionosphere, United Nations/Japan for Space Weather Symposium, 2015.03. |
| 155. |
H. Matsushita, Akimasa Yoshikawa, The features of vertical component of daily geomagnetic field during geomagnetic storm, United Nations/Japan for Space Weather Symposium, 2015.03. |
| 156. |
K. Akimoto, Akimasa Yoshikawa, Characteristics of equatorial Pc 5 during electron flux enhancement, United Nations/Japan for Space Weather Symposium, 2015.03. |
| 157. |
F. Cuturrufo, V. Pilipenko, B. Heilig, M. Stepanova, H. Luehr, P. Vega, A. Yoshikawa, Near-equatorial Pi2 and Pc3 waves observed by CHAMP and on SAMBA/MAGDAS stations, ADVANCES IN SPACE RESEARCH, 2015.02, We have examined simultaneous ULF activity in the Pi2 and Pc3 bands at the near-equatorial magnetic stations in South America from SAMBA and MAGDAS arrays and low-orbiting CHAMP satellite during its passage over this meridional network. At the nighttime, both Pi2 and Pc3 waves in the upper ionosphere and on the ground are nearly of the same magnitude and in-phase. At the same time, the daytime Pc3 pulsations on the ground and in space are nearly out-of-phase. Comparison of observational results with the theoretical notions on the MHD wave interaction with the system ionosphere atmosphere ground suggests that nighttime low-latitude Pi2 and Pc3 wave signatures are produced by magnetospheric fast compressional mode. The daytime near-equatorial Pc3 waves still resist a quantative interpretation. These waves may be produced by a combination of two mechanisms: compressional mode leakage through the ionosphere, and by oscillatory ionospheric current spreading towards equatorial latitudes. (C) 2014 COSPAR. Published by Elsevier Ltd. All rights reserved.. |
| 158. |
Akimasa Yoshikawa, Hideaki Kawano, S. Abe, T. Uozumi, M. Grace, G. Maeda, ICSWSE MAGDAS project, National school on Space and Earth Electromagnetism(SEE) 2014, 2014.12. |
| 159. |
Hideaki Kawano, V. Pilipenko, I. Mann, D. Milling, S. Saita, K. Kitamura, Kiyohumi Yumoto, Akimasa Yoshikawa, Improved Hodograph Method and the Amplitude-Phase Gradient Method to estimate the latitude dependence of the FLR frequency, plasma density, and the resonance width using data from a ground magnetometer pair: Application to CARISMA and MAGDAS station pairs in North America, AGU fall meeting, 2014.12. |
| 160. |
Iyemori T, K. Shiokawa, T. Nakamura, T. Obara, Kiyohumi Yumoto, T. Tsuda, K. Shibata, I. Shinohara, Y. Takahashi, Akimasa Yoshikawa, B. Ritschel, A Proposal of Global Data System for Solar-Terrestrial Sciencea, AGU fall meeting, AGU fall meeting, 2014.12. |
| 161. |
Kiyohumi Yumoto, Akimasa Yoshikawa, Hideaki Kawano, S. Abe, T. Uozumi, M. Grace, G. Maeda, Recent developments from ICSWSE/MAGDAS Research Project, AGU fall meeting, 2014.12. |
| 162. |
Imajo S., T. Uozumi, S. Ohtani, A. Nakamizo, Kiyohumi Yumoto, Akimasa Yoshikawa, Pi 2 Pulsations Associated with Ionospheric Currents Produced By Oscillating Nightside Field-Aligned Currents, AGU fall meeting, 2014.12. |
| 163. |
Kitamura K., T. Nagatsuma, O. Troshichev, T. Obara, H. Koshiishi, S. Saita, Akimasa Yoshikawa, Kiyohumi Yumoto, Relationship between Relativistic Electron Flux in the Inner Magnetosphere and ULF Pulsation on the Ground Associated with Long-term Variations of Solar Wind, AGU fall meeting, 2014.12. |
| 164. |
吉川 顕正, Technical Presentation on the International Center for Space Weather Science and Education (ICSWSE) of Kyushu University, Geomagnetic Workshop in Medan (North Sumatra, Indonesia), 2014.09. |
| 165. |
吉川 顕正, Magnetosphere-Ionosphere Coupling through Alfven Wave, SCOSTEP/ISWI International Space Science School (ISSS) in Peru, SCOSTEP/ISWI International Space Science School (ISSS) in Peru, 2014.09. |
| 166. |
Akimasa Yoshikawa, Hideaki Kawano, Shuji Abe, T. Uozumi, M. Grace, G. Maeda, Space Science Capacity Building at International Center for Space Weather Science and Education (ICSWSE), United Nations / Austria Symposium on “Space Science and the United Nations”, 2014.09. |
| 167. |
吉川 顕正, Theory of Cowling channel formation by reflection of shear Alfven waves from the auroral Ionosphere, AGU Chapman Conference on Low-Frequency Waves in Space Plasmas, 2014.08, Cowlingチャンネルとは電離圏に於けるHall電流が電気伝導度勾配領域において発散成分をもつことによって生じる分極電場により、２次的に励起されるHall電流によって誘導された電流系の総称であり、本来のHall電流と２次的なHall電流が同方向に流れる事により、オーロラジェット電流や、赤道ジェット電流等の強力に強調されたジェット電流効果を生み出す基本メカニズムを内包していることは良く知られている。しかしながら、このジェット電流効果を定量的にコントロールするHall電流発散の電離圏内への閉じ込め効率、Hall電流がどれくらいの割合で電離圏内に閉じ込められ、どれくらいの割合で磁気圏に沿磁力線電流として流出するのか？それによってどれくらいの強さの２次的分極電場が生成され、どの程度ジェット電流効果が生み出されるのか？という問題が理論的にも観測的にも不明なままであった。本論文では、沿磁力線電流を形成するshear Alfven waveと相互作用するHall電流系の発散部分を一意に決定する理論枠組を構築し、Hall電流の電離圏内閉じ込め効率の定式化を初めて行う事により、電離圏で最もダイナミックに変動するジェット電流系の定量的解析を可能とする道筋を示したマイルストーン的な論文である。. |
| 168. |
Akimasa Yoshikawa, Technical presentation on the “International Center for Space Wather Science and Education”, Kyushu University, 第52回国連宇宙平和利用委員会, 2014.02. |
| 169. |
Akimasa Yoshikawa, On formation of Global Cowling channel in the ionosphere and the generalized Ohm’s Law, AGU General Assembly 2013, 2013.12. |
| 170. |
A. Nakamizo, Akimasa Yoshikawa, Shinichi Ohtani, Akimasa Ieda, Kanako Seki, Rotation of the ionospheric electric potential caused by spatial gradients of ionospheric conductivity, AGU General Assembly 2013, 2013.12. |
| 171. |
G. Maeda, Akimasa Yoshikawa, S. Abe, Progress of the MAGDAS Project During 2013, AGU General Assembly 2013, 2013.12. |
| 172. |
Hideaki Kawano, Viacheslav Pilipenko, Ian R. Mann, David K. Milling, Kentarou Kitamura, Akimasa Yoshikawa, Kiyohumi Yumoto, Latitude profiles of the FLR frequency and the resonance width estimated by using the improved hodograph method and the APGM method, AGU General Assembly 2013, 2013.12. |
| 173. |
Magdi E Yousif Suliman, Akimasa Yoshikawa, K. Yumoto, Hideaki Kawano, Teiji Uozumi, S. Abe, M. G. Cardinal, Paolo Palangio, Lynn Kaisan, The relation between amplitudes of a global-mode Pc 5 pulsations and geosynchronous electron fluxes, 2013 3rd IEEE International Conference on Space Science and Communication, IconSpace 2013, 2013.12, Associative relationship between magnetospheric ULF waves in the Pc 5 range (1.7-6.7 mHz) and high energetic particles on the geosynchronous orbit has been investigated in detail in past studies. In particular, there has been interest in the efficiency of global Pc 5 waves, i.e., those having small m-numbers, in accelerating particles [1]. In this paper we investigated this feature by using energetic electron fluxes at geosynchronous orbits, and by using low-latitude global-mode Pc 5 pulsations: We used superposed epoch analyses to show correlations.. |
| 174. |
Magdi E.Yousif Suliman, A. Yoshikawa, K. Yumoto, H. Kawano, Teiji Uozumi, S. Abe, M. G. Cardinal, Paolo Palangio, Lynn Kaisan, The relation between amplitudes of a global-mode Pc 5 pulsations and geosynchronous electron fluxes, 2013 3rd IEEE International Conference on Space Science and Communication, IconSpace 2013, 2013.12, Associative relationship between magnetospheric ULF waves in the Pc 5 range (1.7-6.7 mHz) and high energetic particles on the geosynchronous orbit has been investigated in detail in past studies. In particular, there has been interest in the efficiency of global Pc 5 waves, i.e., those having small m-numbers, in accelerating particles [1]. In this paper we investigated this feature by using energetic electron fluxes at geosynchronous orbits, and by using low-latitude global-mode Pc 5 pulsations: We used superposed epoch analyses to show correlations.. |
| 175. |
Cardinal, M.G, Akimasa Yoshikawa, Hideaki Kawano, Huixin Liu, Masakazu Watanabe, S. Abe, T. Uozumi, G. Maeda, Tohru Hada, Kiyohumi Yumoto, Capacity building activities at ICSWSE, SCOSTEP, International CAWSES-II meeting, 2013.11. |
| 176. |
G. Maeda, Kiyohumi Yumoto, Hideaki Kawano, Akimasa Yoshikawa, Huixin Liu, Masakazu Watanabe, S. Abe, T. Uozumi, A. Ikeda, Cardinal, M.G, MAGDAS activities of year 2013, SCOSTEP, International CAWSES-II meeting, 2013.11. |
| 177. |
Nuraeni, F., A. Santoso, C. Y. Yatini, Akimasa Yoshikawa, S. Abe, Kiyohumi Yumoto, Pc5 activity during geomagnetic storm in Indonesia, SCOSTEP, International CAWSES-II meeting, 2013.11. |
| 178. |
S. Abe, Akimasa Yoshikawa, Hideaki Kawano, T. Uozumi, A. Ikeda, Cardinal, M.G, G. Maeda, Kiyohumi Yumoto, Rebuild of data distribution service for MAGDAS/CPMN project
, SCOSTEP, International CAWSES-II meeting, SCOSTEP, International CAWSES-II meeting, 2013.11. |
| 179. |
Ueno, S, Kiyohumi Yumoto, Akimasa Yoshikawa, K. Makita, K. Munakata, A Mizuno, T. Tsuda, Report of capacity-building activities of Japan during CAWSES-II period, SCOSTEP, International CAWSES-II meeting, 2013.11. |
| 180. |
Asia-Pacific Regional Collaboration for Long-term Sustainability of Outer Space Activities. |
| 181. |
Akimasa Yoshikawa, MAGDAS/CPMN Project, UN/Austria Symposium on “Space Weather Data, Instruments and Models: Looking Beyond the International Space Weather Initiative, 2013.09. |
| 182. |
Akimasa Yoshikawa, Modeling of 3-fluid dynamic and generalized Ohm’s law for understanding ionospheric dynamics, JSPS Core-to-Core Program, 2013 ISWI and MAGDAS Africa School, 2013.09. |
| 183. |
G. Maeda, Kiyohumi Yumoto, Hideaki Kawano, Akimasa Yoshikawa, A. Ikeda, T. Uozumi, Huixin Liu, S. Abe, Masakazu Watanabe, Cardinal, M.G, MAGDAS Activities in Australia Since 2005, AOGS Annual meeting, 2013.06. |
| 184. |
Hiroki MATSUSHITA, Akimasa Yoshikawa, T. Uozumi, A. Ikeda, Kiyohumi Yumoto, Ionospheric Current Identified by Propagation Characteristics of DP2 and Pc5, AOGS Annual meeting, 2013.06, 81. Hiroki MATSUSHITA, Akimasa YOSHIKAWA, Teiji UOZUMI, Akihiro IKEDA, Kiyohumi YUMOTO (2013), Ionospheric Current Identified by Propagation Characteristics of DP2 and Pc5, AOGS Annual meeting, 24-28, June, 2013, Brisbane, Australia. |
| 185. |
Shun Imajo, Akimasa Yoshikawa, T. Uozumi, S.Ohtani, Kiyohumi Yumoto, Characteristics of Azimuthally Polarized Pi 2 on the Morning Side, AOGS Annual meeting, 2013.06. |
| 186. |
Yuki OBANA, Frederick MENK, Colin WATERS, Murray SCIFFER, Akimasa Yoshikawa, Farideh HONARY, Mark MOLDWIN, Ian MANN, David BOTELE, Vassilis ANGELOPOULOS, Chris RUSSELL, Characteristics of Quarter-Wave ULF Pulsations Around the Dawn Terminator, AOGS Annual meeting, 2013.06. |
| 187. |
Magdi Elfadil Yousif Suliman, 吉川 顕正, 魚住 禎司, 湯元 清文, Remotely sensed of some parameters of the solar wind via a low-latitude Pc 5 index, 2013年度日本地球惑星科学連合大会, 2013.05. |
| 188. |
Akimasa Yoshikawa, State-of-art in 3D Ionosphere and internal ionospheric dynamics effect on M-I coupling, ISSI Forum "Near Earth Electro-magnetic Environment (Swarm and Cluster), 2013.04. |
| 189. |
Akimasa Yoshikawa, Current Closure from Polar to Equatorial Ionosphere via Cowling Channel,, EGU General Assembly 2013, 2013.04. |
| 190. |
Akimasa Yoshikawa, M-I couping theory, ECLAT Project Meeting, 2nd Project Review Graz, 2013.04. |
| 191. |
Akimasa Yoshikawa, Technical presentation on the “International Center for Space Wather Science and Education”, Kyushu University, 第50回国連宇宙平和利用委員会, 2013.02. |
| 192. |
Akimasa Yoshikawa, Analogy of Magnetosphere-Ionosphere coupling and Corona-chromosphere-photosphere coupling, ISSI Workshop on "Standing MHD Waves", 2013.02. |
| 193. |
Akimasa Yoshikawa, Formation of Cowling channel from Polar to Equatorial Ionosphere, the 2012 AGU Fall Meeting, 2012.12. |
| 194. |
Akimasa Yoshikawa, Establishment of International Center fot Space Science and education, United Nations/Ecuador Workshop on the International Space Weather Initiative (20th Workshop of the United Nations Basic Space Science Initiative), 2012.10. |
| 195. |
Akimasa Yoshikawa, Extraction of polarization field and magnetospheric impedance from the M-I coupled system via shear Alfven wave, 第132回 地球電磁気･地球惑星圏学会総会・講演会, 2012.10. |
| 196. |
Akimasa Yoshikawa, Aoi Nakamizo, Shin Ohtani, Teiji Uozumi, Y. Tanaka, Formation of FAC -Cowling channel connecting from polar to equatorial ionosphere, 第132回 地球電磁気･地球惑星圏学会総会・講演会, 2012.10. |
| 197. |
Aoi Nakamizo, Akimasa Yoshikawa, T. Hori, A. Ieda, Y. Hiraki, K. Seiki, Y. Miyoshi, T. Kikuchi, Y. Ebihara, The Response of the Dayside Equatorial Electrojet to Step-like Changes of IMF Bz, 第132回 地球電磁気･地球惑星圏学会総会・講演会, 2012.10. |
| 198. |
Magdi Yousif suliman, Kiyohumi Yumoto, Akimasa Yoshikawa, Teiji Uozumi, Global-mode Pc 5 pulsations: Ground distribution and correlation with energetic particles in the inner magnetosphere, 第132回 地球電磁気･地球惑星圏学会総会・講演会, 2012.10. |
| 199. |
Maria Gracita Cardinal, Hideaki Kawano, Kiyohumi Yumoto, Akimasa Yoshikawa, Teiji Uozumi, Shuji Abe, Babatunde Rabiu, The relationship between solar wind parameters and dayside equatorial Pc 4 pulsations, 第132回 地球電磁気･地球惑星圏学会総会・講演会, 2012.10. |
| 200. |
Run Shi, Huixin Liu, Akimasa Yoshikawa, 1D simulation of Electron acceleration by Inertial Alfven wave pulse, 第132回 地球電磁気･地球惑星圏学会総会・講演会, 2012.10. |
| 201. |
Shin Ohtani, Teiji Uozumi, Hideaki Kawano, Akimasa Yoshikawa, Kiyohumi Yumoto, The Response of the Dayside Equatorial Electrojet to Step-like Changes of IMF Bz, 第132回 地球電磁気･地球惑星圏学会総会・講演会, 2012.10. |
| 202. |
Teiji Uozumi, Kiyohumi Yumoto, Akimasa Yoshikawa, Substorm current wedge model for Pi 2 pulsation revisited with the morphology of the global high-correlation Pi 2, 第132回 地球電磁気･地球惑星圏学会総会・講演会, 2012.10. |
| 203. |
Akimasa Yoshikawa, Opening of International Space Wather Science and Education, UN/Austria Symposium on Space Weather Data Analysis, 2012.09. |
| 204. |
Akimasa Yoshikawa, Modeling of 3D Sq current system, JSPS Core-to-Core Program, 2012 ISWI and MAGDAS School on Space Science, 2012.09. |
| 205. |
Yuki Obana, Akimasa Yoshikawa, Characteristics of Quarter-Wave ULF Pulsations around the dawn terminator, AOGS 10th Annual Meeting, 2012.06. |
| 206. |
Nurul Shazana Abdul Hamid, 湯元 清文, LIU HUIXIN, 魚住禎司, 河野 英昭, 吉川 顕正, Mo-hamad Huzaimy Bin Jusoh, Solar cycle dependence of the solar wind control on the geomagnetic activity, 2012年度日本地球惑星科学連合大会, 2012.05. |
| 207. |
吉川 顕正, Ryoichi Fujii, Olaf Amm, Heikki Vanhamakki, On the importance of the Cowling/polarization mechanism for the electrodynamics of the ionosphere and magnetosphere, 2012年度日本地球惑星科学連合大会, 2012.05. |
| 208. |
吉川 顕正, Shin Ohtani, 中溝葵, 魚住禎司, Kiyohumi Yumoto, 極域から磁気赤道域にかけて形成されるCowlingチャンネル, 2012年度日本地球惑星科学連合大会, 2012.05. |
| 209. |
吉川 顕正, 細川 敬祐, 小川 泰信, 電離圏に於ける入反射Alfven 波の分離, 2012年度日本地球惑星科学連合大会, 2012.05. |
| 210. |
吉川 顕正, 魚住禎司, 湯元 清文, Sq電流系に於ける3次元カウリングチャンネルモデル, 2012年度日本地球惑星科学連合大会, 2012.05. |
| 211. |
Terumasa Tokunaga, Daisuke Ikeda, Kazuyuki Nakamura, Tomoyuki Higuchi, Akimasa Yoshikawa, Teiji Uozumi, Akiko Fujimoto, Akira Morioka, Kiyofumi Yumoto, Detecting precursory events in time series data by an extension of singular spectrum transformation, 10th WSEAS International Conference on Applied Computer Science, ACS'10, 2010.12, To predict an occurrence of extraordinary phenomena, such as earthquakes, failures of engineering system and financial market crushes, it is important to identify precursory events in time series. However, existing methods are limited in their applicability for real world precursor detections. Recently, Ide and Inoue [1] have developed an SSA-based change-point detection method, called singular spectrum transformation (SST). In this paper, we extend the SST so that it is applicable for real world precursor detections, focusing on the wide applicability of the conventional SST. Although the SST is suitable for detecting various types of change-points, detecting precursors can be far more difficult than expected because, in general, real world time series contains measurement noise and non-stationary trends. Furthermore, precursory events are usually observed as minute and less-visible fluctuations preceding an onset of massive fluctuations of extraordinary phenomena and therefore they are easily over-looked. To overcome this, we extend the conventional SST to the multivariable SST, focusing on the synchronism detection of precursory events in multiple sequences of univariate time series. First, we would like to define the problem setting of real world precursory detections and consider its difficulties. Second, the multivariable SST is introduced. Third, we apply SST to geomagnetic time series data and show the multivariable SST is more suitable than the conventional SST for real world precursor detections. Finally, we show further experimental results using artificial data to evaluate the reliability of SST-based precursor detections.. |
| 212. |
Terumasa Tokunaga, Daisuke Ikeda, Kazuyuki Nakamura, Tomoyuki Higuchi, Akimasa Yoshikawa, Teiji Uozumi, Akiko Fujimoto, Akira Morioka, Kiyofumi Yumoto, Detecting precursory events in time series data by an extension of singular spectrum transformation, 10th WSEAS International Conference on Applied Computer Science, ACS'10, 2010.12, To predict an occurrence of extraordinary phenomena, such as earthquakes, failures of engineering system and financial market crushes, it is important to identify precursory events in time series. However, existing methods are limited in their applicability for real world precursor detections. Recently, Ide and Inoue [1] have developed an SSA-based change-point detection method, called singular spectrum transformation (SST). In this paper, we extend the SST so that it is applicable for real world precursor detections, focusing on the wide applicability of the conventional SST. Although the SST is suitable for detecting various types of change-points, detecting precursors can be far more difficult than expected because, in general, real world time series contains measurement noise and non-stationary trends. Furthermore, precursory events are usually observed as minute and less-visible fluctuations preceding an onset of massive fluctuations of extraordinary phenomena and therefore they are easily over-looked. To overcome this, we extend the conventional SST to the multivariable SST, focusing on the synchronism detection of precursory events in multiple sequences of univariate time series. First, we would like to define the problem setting of real world precursory detections and consider its difficulties. Second, the multivariable SST is introduced. Third, we apply SST to geomagnetic time series data and show the multivariable SST is more suitable than the conventional SST for real world precursor detections. Finally, we show further experimental results using artificial data to evaluate the reliability of SST-based precursor detections.. |
| 213. |
Annual and Semiannual Variations of Equivalent Sq Current System along the 210 MM CPMN Stations. |
| 214. |
Annual and Semiannual Variations of Equivalent Sq Current System along the 210 MM CPMN Stations. |
| 215. |
Yutaka Hirata, Akimasa Yoshikawa, Pablo M. Blazquez, Stephen M. Highstein, Evaluation of the inverse dynamic model in cerebellum during visual-vestibular interactions at different VOR gains in squirrel monkeys, Neurocomputing, 2005.06, Generality of the cerebellar inverse dynamic model (IDM) theory was evaluated in oculomotor control in squirrel monkeys. Flocculus Purkinje cell firing patterns recorded during visual, vestibular, and their interaction paradigms at various vestibuloocular reflex (VOR) gains were reconstructed by the IDM consisting of the linear combination of eye position, velocity, and acceleration. The IDM could successfully reconstruct more than 72% of the firing patterns of 138 cells, but with different sets of parameters for different paradigms and different VOR gains. This result suggests that the output of the flocculus relates to motor output, but not the motor command per se. © 2004 Elsevier B.V. All rights reserved.. |
| 216. |
M Shinohara, K Yumoto, A Yoshikawa, O Saka, SI Solovyev, EF Vershinin, NB Trivedi, JM Da Costa, Wave characteristics of daytime and nighttime Pi 2 pulsations at the equatorial and low latitudes (vol 24, pg 2279, 1997), GEOPHYSICAL RESEARCH LETTERS, 1998.09. |
| 217. |
糸長雅弘, 吉川顕正, 湯元清文, Transient response of the non-uniform equatorial ionosphere to the ionospheric current of polar region, 地球惑星科学関連学会1998合同大会, 1998.05. |
