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The electric field in the polar ionosphere is imposed as a result of physical processes in the magnetosphere. The modeling of the magnetospheric processes is thus essential to reproduce physical phenomena in the polar ionosphere. Nowadays, magneto-hydrodynamic (MHD) models of the magnetosphere produce a realistic ionospheric potential pattern. Therefore, data assimilation into an MHD model would be a promising approach to reproduce ionospheric phenomena with high accuracy. However, the realistic MHD model is too computationally expensive to apply data assimilation. To overcome the problem of the computational cost, we employ a machine learning-based emulator of the global MHD model. The emulator is based on an echo state network model and efficiently mimics the MHD model to reproduce an ionospheric potential pattern under a give solar wind condition. As a pilot study, we assimilate the SuperDARN data into this emulator and obtain the global potential map. We will demonstrate the electric potential maps as a result of data assimilation into the emulator., The 28th IUGG General Assembly (IUGG2023) (Berlin 2023)

In-situ observations of spatial variations of the wave-particle interaction region require a large number of satellite probes. As an alternative, flash-type auroras, a kind of pulsating aurora, driven by discrete chorus elements, can be used to investigate the interaction region with a high spatial resolution. We estimated the spatial extent of wave-particle interaction region from ground-based observations of flash aurora at Gakona (62.39°N, 214.78°E), Alaska at subauroral latitudes, and found that the auroral expansion was predominantly to the low-latitude side. The spatial displacement is thought to be caused by the propagation effects of chorus waves in the magnetosphere. Using ray tracing analysis to take into account chorus wave propagation, we reconstructed the spatiotemporal evolution of the volume emission rate and confirmed that the predominant expansion is toward the lower-latitude side in the ionosphere. This study shows that chorus wave propagation in the magnetosphere gives new insight for characterizing the transverse size (across the geomagnetic field line) of wave-particle interaction regions. The calculated spatial scale of the column auroral emission shows a correlation with the magnetic latitude of the resonance region at magnetic latitudes within 10° of the equatorial plane of the magnetosphere. Our results suggest that the spatial scale of a flash aurora is indirectly related to the chorus amplitude because the latitudinal range of the wave-particle interaction is important for the growth of wave amplitude.

Small-scale dynamic auroras have spatial scales of a few km or less, and temporal scales of a few seconds or less, which visualize the complex interplay among charged particles, Alfvén waves, and plasma instabilities working in the magnetosphere-ionosphere coupled regions. We summarize the observed properties of flickering auroras, vortex motions, and filamentary structures. We also summarize the development of fundamental theories, such as dispersive Alfvén waves (DAWs), plasma instabilities in the auroral acceleration region, ionospheric feedback instabilities (IFI), and the ionospheric Alfvén resonator (IAR).

第21回宇宙科学シンポジウム (2021年1月6日-7日. オンライン開催), 21st Space Science Symposium (January 6-7, 2021. Online Meeting), 著者人数: 25名, 資料番号: SA6000163125, レポート番号: g20-2

第21回宇宙科学シンポジウム (2021年1月6日-7日. オンライン開催), 21st Space Science Symposium (January 6-7, 2021. Online Meeting), 資料番号: SA6000163072, レポート番号: g07-4

This chapter reviews fundamental properties and recent advances of diffuse and pulsating aurora. Diffuse and pulsating aurora often occurs on closed field lines and involves energetic electron precipitation by wave-particle interaction. After summarizing the definition, large-scale morphology, types of pulsation, and driving processes, we review observation techniques, occurrence, duration, altitude, evolution, small-scale structures, fast modulation, relation to high-energy precipitation, the role of ECH waves, reflected and secondary electrons, ionosphere dynamics, and simulation of wave-particle interaction. Finally we discuss open questions of diffuse and pulsating aurora.

第20回宇宙科学シンポジウム (2020年1月8日-9日. 宇宙航空研究開発機構宇宙科学研究所(JAXA)(ISAS)相模原キャンパス), 相模原市, 神奈川県, 20th Space Science Symposium (January 8-9, 2020. Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency(JAXA)(ISAS)Sagamihara Campus), Sagamihara, Kanagawa Japan, 資料番号: SA6000152125, レポート番号: P2.19

第20回宇宙科学シンポジウム (2020年1月8日-9日. 宇宙航空研究開発機構宇宙科学研究所(JAXA)(ISAS)相模原キャンパス), 相模原市, 神奈川県, 20th Space Science Symposium (January 8-9, 2020. Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency(JAXA)(ISAS)Sagamihara Campus), Sagamihara, Kanagawa Japan, 著者人数: 29名, 資料番号: SA6000152143, レポート番号: P2.37

第13回宇宙環境シンポジウム (2016年11月1日-2日. 情報通信研究機構 本部 国際会議室), 小金井市, 東京, The 13th Spacecraft Environment Symposium (November 1-2, 2016. National Institute of Information and Communications Technology), Koganei, Tokyo, Japan, 形態: カラー図版あり, Physical characteristics: Original contains color illustrations, 資料番号: AA1630038003, レポート番号: JAXA-SP-16-010

著者人数: 23名, Accepted: 2019-01-11, 資料番号: SA1180319000

著者人数: 15名, Accepted: 2016-07-26, 資料番号: SA1160115000

第18回宇宙科学シンポジウム (2018年1月9日-10日. 宇宙航空研究開発機構宇宙科学研究所(JAXA)(ISAS)相模原キャンパス), 相模原市, 神奈川県, 18th Space Science Symposium (January 9-10, 2018. Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency(JAXA)(ISAS)Sagamihara Campus), Sagamihara, Kanagawa Japan, 著者人数: 40名, 資料番号: SA6000118055, レポート番号: P-021

第8回極域科学シンポジウム/個別セッション：[OS] 宙空圏12月6日（水）統計数理研究所 3階セミナー室D304The Eighth Symposium on Polar Science/Ordinary sessions: [OS] Space and upper-atmosphere sciencesWed. 6 Dec./3F Seminar room D304, Institute of Statistics and Mathematics

第8回極域科学シンポジウム/個別セッション：[OS] 宙空圏12月6日（水）統計数理研究所 3階セミナー室D304The Eighth Symposium on Polar Science/Ordinary sessions: [OS] Space and upper-atmosphere sciencesWed. 6 Dec./3F Seminar room D304, Institute of Statistics and Mathematics

第8回極域科学シンポジウム/個別セッション：[OS] 宙空圏12月6日（水）統計数理研究所 3階セミナー室D304The Eighth Symposium on Polar Science/Ordinary sessions: [OS] Space and upper-atmosphere sciencesWed. 6 Dec./3F Seminar room D304, Institute of Statistics and Mathematics

第8回極域科学シンポジウム/個別セッション：[OS] 宙空圏12月5日（火）国立極地研究所 1階交流アトリウムThe Eighth Symposium on Polar Science/Ordinary sessions: [OS] Space and upper-atmosphere sciencesTue. 5 Dec./Entrance Hall (1st floor), National Institute of Polar Research

第8回極域科学シンポジウム/個別セッション：[OS] 宙空圏12月5日（火）国立極地研究所 1階交流アトリウムThe Eighth Symposium on Polar Science/Ordinary sessions: [OS] Space and upper-atmosphere sciencesTue. 5 Dec./Entrance Hall (1st floor), National Institute of Polar Research

The plasmas (electrons and ions) in the inner magnetosphere have wide energy ranges from electron volts to mega-electron volts (MeV). These plasmas rotate around the Earth longitudinally due to the gradient and curvature of the geomagnetic field and by the co-rotation motion with timescales from several tens of hours to less than 10 min. They interact with plasma waves at frequencies of mHz to kHz mainly in the equatorial plane of the magnetosphere, obtain energies up to MeV, and are lost into the ionosphere. In order to provide the global distribution and quantitative evaluation of the dynamical variation of these plasmas and waves in the inner magnetosphere, the PWING project (study of dynamical variation of particles and waves in the inner magnetosphere using ground-based network observations, (http://www.isee.nagoya-u.ac.jp/dimr/PWING/) has been carried out since April 2016. This paper describes the stations and instrumentation of the PWING project. We operate all-sky airglow/aurora imagers, 64-Hz sampling induction magnetometers, 40-kHz sampling loop antennas, and 64-Hz sampling riometers at eight stations at subauroral latitudes (~ 60° geomagnetic latitude) in the northern hemisphere, as well as 100-Hz sampling EMCCD cameras at three stations. These stations are distributed longitudinally in Canada, Iceland, Finland, Russia, and Alaska to obtain the longitudinal distribution of plasmas and waves in the inner magnetosphere. This PWING longitudinal network has been developed as a part of the ERG (Arase)-ground coordinated observation network. The ERG (Arase) satellite was launched on December 20, 2016, and has been in full operation since March 2017. We will combine these ground network observations with the ERG (Arase) satellite and global modeling studies. These comprehensive datasets will contribute to the investigation of dynamical variation of particles and waves in the inner magnetosphere, which is one of the most important research topics in recent space physics, and the outcome of our research will improve safe and secure use of geospace around the Earth. Published version

Electromagnetic ion cyclotron (EMIC) waves, one of the possible origins of flickering aurora, have been thought to modulate the electron flux at a few thousand kilometers. In fact, flickering aurora with a frequency range of 3–15 Hz has often been identified by ground-based optical observations and has been interpreted to be caused by O+-band EMIC waves. However, extant research to date has not identified possible signatures of H+-band EMIC waves due to technical limitations of ground-based high-speed imagers. The present study shows the first evidence that patchy flickering aurora could be modulated by H+-band EMIC waves, based on the data obtained from imaging observations at 160 frames per second. The sporadic appearance of the flickering aurora in the frequency range of 50–80 Hz coexisted with typical flickering auroras of approximately 10 Hz. These results are consistent with the hypothesis that flickering auroras are generated by multi-ion EMIC waves.

Solar energetic particles (SEPs) sometimes induce powerful air showers that significantly increase the radiation dose at flight altitudes. In order to provide information of such a space radiation hazard to aircrew, a forecast model is developed for WASAVIES (Warning System of Aviation Exposure to SEP), based on the focused transport equation of solar protons and Monte Carlo particle transport simulation of the air shower. WASAVIES gives a simple and fastway to predict the time profile of dose rate during ground-level enhancements.

WASAVIES, a warning system for aviation exposure to solar energetic particles (SEPs), is under development by collaboration between several institutes in Japan and the USA. It is designed to deterministically forecast the SEP fluxes incident on the atmosphere within 6 h after flare onset using the latest space weather research. To immediately estimate the aircrew doses from the obtained SEP fluxes, the response functions of the particle fluxes generated by the incidence of monoenergetic protons into the atmosphere were developed by performing air shower simulations using the Particle and Heavy Ion Transport code system. The accuracy of the simulation was well verified by calculating the increase count rates of a neutron monitor during a ground-level enhancement, combining the response function with the SEP fluxes measured by the PAMELA spectrometer. The response function will be implemented in WASAVIES and used to protect aircrews from additional SEPexposure.

第7回極域科学シンポジウム:[OS]宙空圏11月29日（火）国立極地究所 1階 交流アトリウム

第7回極域科学シンポジウム:[OS]宙空圏11月29日（火）統計数理研究所 3階 セミナー室D305

第7回極域科学シンポジウム:[OS]宙空圏11月29日（火）国立極地究所 1階 交流アトリウム

第7回極域科学シンポジウム:[OS]宙空圏11月29日（火）国立極地究所 1階 交流アトリウム

第7回極域科学シンポジウム:[OS]宙空圏11月29日（火）統計数理研究所 3階 セミナー室D305

Galactic cosmic rays and solar protons ionize the present terrestrial atmosphere, and the air showers are simulated by well-tested Monte-Carlo simulations, such as PHITS code. We use the latest version of PHITS to evaluate the possible ionization of protoplanetary disks by galactic cosmic rays (GCRs), solar protons, and by supernova remnants. The attenuation length of GCR ionization is updated as 118 g cm-2, which is approximately 20% larger than the popular value. Hard and soft possible spectra of solar protons give comparable and 20% smaller attenuation lengths compared with those from standard GCR spectra, respectively, while the attenuation length is approximately 10% larger for supernova remnants. Further, all of the attenuation lengths become 10% larger in the compound gas of cosmic abundance, e.g. 128 g cm-2 for GCRs, which can affect the minimum estimate of the size of dead zones in protoplanetary disks when the incident flux is unusually high.

People have probably been watching the sky since the beginning of human history. Observers in pre-telescopic ages recorded anomalous events and these astronomical records in the historical documents provide uniquely valuable information for modern scientists. Records with drawings are particularly useful, as the verbal expressions recorded by pre-telescopic observers, who did not know the physical nature of the phenomena, are often ambiguous. However, drawings for specific datable events in the historical documents are much fewer than the verbal records. Therefore, in this paper, we show the possible earliest drawings of datable auroras and a two-tail comet in a manuscript of the Chronicle of Z��qn��n, a Syriac chronicle up to 775/776 CE to interpret their nature. They provide not only the historical facts in the realm around Amida but also information about low-latitude aurora observations due to extreme space weather events and the existence of sun-grazing comets., 2016/10/26 accepted for publication in PASJ. Due to the matter of license, we cannot show some figures on the preprint version. Please see the published version in PASJ for the figures

Extreme space weather conditions pose significant problems for standard space weather models which are available for some limited realistic parameter ranges. As a good example anomalous spikes of cosmic ray induced 10Be have been found during the Maunder Minimum (AD1645 1715) at the qA negative solar minima which cannot be quantitatively explained by standard drift theories of cosmic ray transport alone. Such an extreme amplification of solar cycle modulation of cosmic rays is presumably related to the altered condition of heliospheric environment at the prolonged sunspot disappearance providing a clue for comprehensive understandings of long term changes in heliospheric environment solar cycle modulation of cosmic rays and the maximal range of incident cosmic ray flux that is very important for our practical space activities. Model sophistication to achieve precise forecast of such extreme condition of the heliosphere and the incoming cosmic ray flux is also of urgent need as the Sun is currently showing a tendency toward lower activity. Here we show that the cosmic ray spikes found at the Maunder Minimum may be explained by the contribution from the cross sector transport mechanism working in the heliosheath where cosmic ray particles effectively drift across stacked magnetic sectors due to the larger cyclotron radius than the distance between the sectors. Based on the new interpretation of the 10Be record we clarify potentially important problems for space weather modelers to help with more realistic modeling of the heliosphere during periods of extremely weak solar activity such as the Maunder Minimum. © 2012 American Geophysical Union. All Rights Reserved.

第10回宇宙環境シンポジウム (2013年12月2日-3日. 科学技術館), 東京, 10th Spacecraft Environment Symposium (December 2-3, 2013, Science Museum), Tokyo Japan, 形態: カラー図版あり, Physical characteristics: Original contains color illustrations, 資料番号: AA0062301019, レポート番号: JAXA-SP-13-016

第6回極域科学シンポジウム分野横断型セッション：[IM] 横断 中層大気・熱圏11月17日（火） 国立極地研究所１階交流アトリウム

第6回極域科学シンポジウム[OS] 宙空圏11月16日（月） 国立極地研究所１階交流アトリウム

第6回極域科学シンポジウム[OS] 宙空圏11月16日（月） 国立極地研究所１階交流アトリウム

第6回極域科学シンポジウム[OS] 宙空圏11月16日（月） 国立極地研究所１階交流アトリウム

第6回極域科学シンポジウム[OS] 宙空圏11月16日（月） 国立極地研究所１階交流アトリウム

第6回極域科学シンポジウム[OS] 宙空圏11月16日（月） 国立極地研究所 2階 大会議室

第6回極域科学シンポジウム[OS] 宙空圏11月16日（月） 国立極地研究所 2階 大会議室

第6回極域科学シンポジウム[OS] 宙空圏11月16日（月） 国立極地研究所 2階 大会議室

第6回極域科学シンポジウム[OS] 宙空圏11月16日（月） 国立極地研究所１階交流アトリウム

平成18年度宇宙科学情報解析センターシンポジウム（2006年11月28日. 宇宙航空研究開発機構宇宙科学研究本部(JAXA)(ISAS)）, 相模原市, 神奈川県, 2006 PLAIN Center Symposium (Space Science Informatics Symposium FY2006) (November 28, 2006. Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency (JAXA)(ISAS)), Sagamihara, Kanagawa Japan, 資料番号: SA6000108003