研究者業績

阿部 琢美

アベ タクミ  (Takumi ABE)

基本情報

所属
国立研究開発法人宇宙航空研究開発機構 宇宙科学研究所 太陽系科学研究系 准教授
総合研究大学院大学(総研大) 物理科学研究科 宇宙科学専攻 准教授

J-GLOBAL ID
200901006137313045
researchmap会員ID
1000253786

外部リンク

論文

 81
  • Takumi Abe, Joran Moen
    European Space Agency, (Special Publication) ESA SP 700 SP 625-628 2011年  査読有り
    We present the in-situ measurement of the electron density and its perturbation on the sounding rocket in the ionospheric cusp region during the ICI-2 (Investigation of Cusp Irregularities-2) campaign conducted in Svalbard, Norway in late 2008. The scientific objective of ICI-2 was to investigate generation mechanism(s) of coherent HF radar backscatter targets. Strong coherent HF backscatter echoes are a well-known characteristic of the polar cusp, and are thought to result from field-aligned plasma irregularities with decameter scale length. In this paper, a result from Fixed-Bias Probe (FBP) which aimed at measuring fine-scale (similar to 1 m) electron density perturbation is mainly described.
  • Takumi Abe, Joran Moen
    European Space Agency, (Special Publication) ESA SP 700 SP 43-46 2011年  査読有り
    We present the in-situ measurement of the electron density and its perturbation on the sounding rocket in the ionospheric cusp region during the ICI-2 (Investigation of Cusp Irregularities-2) campaign conducted in Svalbard, Norway in late 2008. The scientific objective of ICI-2 was to investigate generation mechanism(s) of coherent HF radar backscatter targets. Strong coherent HF backscatter echoes are a well-known characteristic of the polar cusp, and are thought to result from field-aligned plasma irregularities with decameter scale length. In this paper, a result from Fixed-Bias Probe (FBP) which aimed at measuring fine-scale (similar to 1 m) electron density perturbation is mainly described.
  • Kurihara, J, Y. Koizumi-Kurihara, N. Iwagami, T. Suzuki, A. Kumamoto, T. Ono, M. Nakamura, M. Ishii, A. Matsuoka, K. Ishisaka, T. Abe, S. Nozawa
    Journal of Geophysical Research 115 2010年12月16日  査読有り
  • J. Kurihara, Y. Koizumi-Kurihara, N. Iwagami, T. Suzuki, A. Kumamoto, T. Ono, M. Nakamura, M. Ishii, A. Matsuoka, K. Ishisaka, T. Abe, S. Nozawa
    Journal of Geophysical Research: Space Physics 115(12) 2010年  査読有り
    To study the spatial structure of midlatitude sporadic E (Es) layers, the ultraviolet resonant scattering by magnesium ions (Mg+) in an Es layer was observed during the evening twilight with the Magnesium Ion Imager (MII) on the sounding rocket launched from the Uchinoura Space Center in Kagoshima, Japan. The in situ electron density measured by an onboard impedance probe showed that the Es layer was located at an altitude of 100 km during both the ascent and descent of the flight. Simultaneous observation with a ground-based ionosonde at Yamagawa identified the signature of horizontally "patchy" structures in the Es layer. The MII successfully scanned the horizontal Mg+ density perturbations in the Es layer and found that they had patchy and frontal structures. The horizontal scale and alignment of the observed frontal structure is generally consistent with a proposed theory. To our knowledge, this is the first observation of the two-dimensional horizontal structure of Mg + in an Es layer. Copyright 2010 by the American Geophysical Union.
  • 齊藤昭則, 阿部琢美, 山崎敦, 鈴木睦, 坂野井健, 藤原均, 吉川一朗, 大塚雄一, 田口真, 山本衛, 中村卓司, 菊池雅行, 江尻省, 河野英昭, 石井守, 久保田実, 星野尾一明, 坂野井和代
    第10回宇宙科学シンポジウム講演集 2010年  
  • N. Kitamura, Y. Nishimura, T. Ono, Y. Ebihara, N. Terada, A. Shinbori, A. Kumamoto, T. Abe, M. Yamada, S. Watanabe, A. Matsuoka, A. W. Yau
    Journal of Geophysical Research: Space Physics 115(11) 2010年11月  査読有り
    Velocity distributions of upflowing ions in the polar ionosphere are crucial to understand their destinations. Natural plasma wave observations by the plasma wave and sounder experiments and thermal ion observations by the suprathermal ion mass spectrometer onboard the Akebono satellite at ∼9000 km altitude in the polar magnetosphere during the geomagnetic storms showed that ions in the region of enhanced electron density in the polar cap were dominated by very-low-energy O+ ions (∼85%) with upward velocities of 4-10 km s-1, corresponding to streaming energies of 1.3-8.4 eV. The fluxes of very-low-energy upflowing O+ ions exceeded 1 × 10 9 cm-2 s-1 (mapped to 1000 km altitude) across wide regions. These signatures are consistent with high-density plasma supplied by the cleft ion fountain mechanism. Trajectory calculations of O+ ions based on the Akebono observations as the initial condition showed the transport paths and accelerations of the O+ ions and indicated that the velocities of the very-low-energy upflowing O+ ions through the dayside polar cap are enough to reach the magnetosphere under strong convection. The calculations suggest the importance of the very-low-energy upflowing O + ions with large fluxes in the total O+ ion supply toward the magnetosphere, especially the near-Earth tail region and inner magnetosphere. The initially very-low-energy O+ ions can contribute significantly to the ring current formation during geomagnetic storms since some of the O+ ions were transported into the ring current region with typical energies of ring current ions (several tens of keV) in the trajectory calculations. Copyright 2010 by the American Geophysical Union.
  • Koizumi Yoshiko, Kubota Minoru, Murayama Yasuhiro, Abo Makoto, Uchiumi Michihiro, Igarashi Kiyoshi, Iwagami Naomoto, Abe Takumi, Oyama Koh-Ichiro
    JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES 114 2009年10月28日  査読有り
  • 栗原 純一, 村田 功, 佐藤 薫, 冨川 喜弘, 阿部 琢美
    宇宙航空研究開発機構研究開発報告 8 43-56 2009年2月  査読有り
    科学気球や観測ロケットなどが飛翔する超高層大気環境における気圧の計測は,技術的にも科学的にも極めて重要である.本研究で開発した飛翔体搭載用小型気圧計は,水晶振動子の共振インピーダンスが圧力に応じて変化する原理を利用した水晶摩擦気圧計と呼ばれるもので,地表から高度100km 付近までに相当する広い計測圧力範囲(10^5〜10^<-2>Pa)に特徴がある.また,センサ部は約100g,データ処理部は約200g と小型軽量であることに加えて1W 以下の低消費電力を達成し,特に重量が厳しく制限される高高度気球などの飛翔体への搭載に適している.腕時計などにも広く使用されている音叉型水晶振動子は耐振動・衝撃性に優れた構造を持ち,高い耐環境性能が要求される観測ロケットにも搭載可能である.本報告では,開発した水晶摩擦気圧計の性能試験結果について述べるとともに,BU30-5 号機を用いた性能実証試験についても報告する.
  • KURIHARA Junichi, ABE Takumi, MURATA Isao, SATO Kaoru, TOMIKAWA Yoshihiro
    TRANSACTIONS OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES, SPACE TECHNOLOGY JAPAN 7(26) Pm_7-Pm_11 2009年  
    The on-board small vacuum gauge developed in this study is the quartz friction gauge, which is based on the principle that the resonance impedance of a quartz oscillator varies with the pressure of ambient gas. The gauge has a wide measuring range (105-10-2 Pa), which corresponds to the atmospheric pressure from the ground to an altitude of about 100 km. The sensor part and data processing part weigh 136 g and 210 g, respectively. In addition, the gauge can operate at a power consumption level of less than 1W. The gauge is suited for high altitude balloon experiments where the weight of on-board instruments must be kept to a minimum. The tuning-fork-shaped quartz oscillator in the gauge is widely used for wrist watches and has high resistance to vibration and shock, and thus the gauge is applicable to sounding rocket experiments that require on-board instruments with high resistance to the environment.
  • Takumi Abe, Masato Nakamura, Nobuaki Ishii, Yoshifumi Inatani
    PROCEEDINGS OF THE 19TH ESA SYMPOSIUM ON EUROPEAN ROCKET AND BALLOON PROGRAMMES AND RELATED RESEARCH 671 23-26 2009年  査読有り
    Sounding rocket experiments have been successively conducted for more than 40 years in Japan. These include various scientific and engineering topics. In this paper, we present recent activities of Japanese sounding rocket experiments for the last two years (2007-2008 fiscal year) and also describe a future direction on the experiment in the mid-term range.
  • Yoshifumi Inatani, Nobuaki Ishii, Takumi Abe, Tetsuya Yoshida
    European Space Agency, (Special Publication) ESA SP 647(647 SP) 19-24 2007年6月  査読有り
    In the fiscal year of 2005 and 2006, Japan Aerospace Exploration Agency (JAXA) had successfully launched 10 space vehicles, which included five application satellites, three scientific observation satellites and two sounding rockets with a single stage solid motor. The Institute of Space and Astronautical Science (ISAS) has been continuously conducting space science programs using sounding rockets, scientific satellites and stratospheric balloons. This paper briefly introduces and summarizes the ISAS space activities in the two years.
  • Satoshi Nonaka, Hiroyuki Ogawa, Yoshihiro Naruo, Nobuaki Ishii, Takumi Abe, Yoshifumi Inatani
    European Space Agency, (Special Publication) ESA SP 647(647 SP) 187-192 2007年6月  査読有り
    A fully reusable rocket vehicle is proposed as a sounding rocket for observations of atmospheric phenomena, micro-gravity experiments and so on. Vehicle systems and ground / flight operations are designed for such science observations. For the development of the reusable rocket, a small test vehicle was built and flight-tested. This Reusable Vehicle Testing (RVT) lessons campaign provide repeated experiences of turnaround operations and vertical take-off and landing flights. In the present design of the reusable sounding rocket, the total length and maximum diameter of the vehicle is about 10m and 3m, respectively. The vehicle is propelled by the propulsion system composed of four liquid hydrogen / liquid oxygen engines. The weight of a payload carried to 120 km altitude is 100kg in the nose-fairing. The instrument for observations can be reused because of the repeated flight. The turnaround time for one flight is less than 24 hours (1 day). In the typical ballistic flight up to 120 km, the flight environments under 10(-5)G acceleration is able to be made for about 120 sec. The flight Mach number can be subsonic around the summit in the trajectory. These properties of reusable sounding rocket are expected to be useful and effective for many science missions.
  • Manabu Shimoyama, Takumi Abe, Koh Ichiro Oyama
    European Space Agency, (Special Publication) ESA SP 647(647 SP) 421-424 2007年6月  査読有り
    Processes of energy cascade from suprathermal to thermal electrons significantly affect the thermal structure of the lower ionosphere. The Suprathermal Plasma Analyzer (SPA) was developed to measure an energy distribution of thermal and suprathermal electrons (&lt; 5 eV). The principle of this analyzer is based on the innovative combination of a second harmonic method and a channel electron multiplier. Outstanding point of this analyzer are: 1) accurate calibration of electron energy within the order of 0.01 eV, and 2) the energy resolution smaller than 0.15 eV. The SPA was installed in the sounding rocket S-310-37 and observed the electron energy distribution function at the height from 100 km to 140 km.
  • Takumi Abe, Manabu Shimoyama, Keigo Ishisaka, Toshimi Okada, Fumio Tohyama, Takao Takahashi, Kiyohumi Yumoto, Koh Ichiro Oyama
    European Space Agency, (Special Publication) ESA SP 647(647 SP) 413-416 2007年6月  査読有り
    The sounding rocket measurements in the mid-latitude ionosphere suggest that the electron temperature occasionally increases at 100-110 km altitudes during daytime in winter. Detailed study indicates that such a temperature increase is closely related to the existence of the Sq current focus, because the temperature increase becomes significant when the measurement is made near the center of the Sq focus. In order to elucidate a mechanism to cause the electron temperature increase, the sounding rocket experiment was conducted in Uchinoura Space Center in Japan on January 16, 2007. The rocket was launched at 11:20 JST after identifying that the Sq current was approaching to the planned rocket trajectory. The rocket certainly observed the local increase of the electron temperature at the altitude of 97-101 kin. We present a preliminary analysis of the data such as the electron temperature, density, and its perturbation obtained during this campaign.
  • Minoru Kubota, Seiji Kawamura, Makoto Abo, Yoshiko Koizumi, Yasuhiro Murayama, Miho Yamamori, Kazuo Shiokawa, Yuichi Otsuka, Michihiro Uchiumi, Kiyoshi Igarashi, Takumi Abe, Koh Ichiro Oyama, Naomoto Iwagami
    Journal of Geophysical Research Atmospheres 111(21) D21110-D21110 2006年11月16日  査読有り
    The Waves in Airglow Campaign in 2004 (WAVE2004), which aimed to elucidate the formation process of waves in airglow structures from both dynamical and chemical perspectives, was conducted using rocket-borne and ground-based instruments in Japan on 17 January 2004. In this experiment, we observed a large-scale atmospheric gravity wave (AGW), which appeared in both the vertical profiles of sodium density obtained by a Na lidar and the horizontal distributions of airglow emission obtained by an all-sky imager (ASI). Vertical propagation of the AGW accompanied by a shortening of its vertical wavelength was clearly visualized using the Na lidar data. The horizontal wavelength, horizontal phase velocity, period, and propagation direction of the AGW were estimated from the ASI data as 673-774 km, 107-122 m/s, ∼1.75 hours, and north-northeastward, respectively. Using these parameters and the MF radar wind, vertical wavelengths of the wave were calculated from the dispersion relation of gravity waves. The calculated vertical wavelengths were comparable at altitudes of 85.5 km and 93.25 km to those estimated from the variation of the sodium density. Using a simple ray tracing technique, the AGW was traced back to the southern edge of the distorted jet stream near tropopause. This result strongly suggests that an unstable baroclinic wave associated with ageostrophic motions in the jet stream was the wave source of the large-scale AGW observed in the WAVE2004. Copyright 2006 by the American Geophysical Union.
  • M. Kanao, N. Terada, A. Yamazaki, I. Yoshikawa, T. Abe, M. Nakamura
    Journal of Geophysical Research: Space Physics 111(3) 2006年3月1日  査読有り
    The purpose of this paper is to clarify how the average structure of the Venus nightside ionopause for solar zenith angles (SZA) greater than 90° depends on (1) the direction and (2) the magnitude of the motional electric field of the solar wind. Plasma density structure in the Venus nightside ionosphere has been investigated by using data sets of the Pioneer Venus Orbiter observations. It is found that the distribution of the nightside ionopause locations is asymmetric with respect to the direction of the solar wind electric field, leaning opposite to the electric field vector. It is also found that the asymmetry is increasingly prominent as the magnitude of the motional electric field increases, while not so prominent for small field magnitude. This result suggests that the asymmetric ionopause location in the nightside is related to the acceleration of pickup ions. Copyright 2006 by the American Geophysical Union.
  • Biff P. Williams, D. C. Fritts, J. D. Vance, C. Y. She, Takumi Abe, Eivind Thrane
    Earth, Planets and Space 58(9) 1131-1137 2006年  
    The sounding rocket for the DELTA (Dynamics and Energetics of the Lower Thermosphere in Aurora) campaign was successfully launched from Andoya at 00:33 UT on Dec 13, 2004. Though it was cloudy at the time of launch, the Weber Na lidar was operating intermittently between 20:00 UT and 23:30 UT on Dec 12, observing Na density, temperature and meridional wind between 80 and 100 km. Throughout the lidar observations, we observed significant small (λz <5 km) and medium-scale (λz≈8-15 km) wave activity producing significant wind and temperature shears. There were unusually large (up to 10 m/s and 10 K amplitudes) perturbations of the vertical wind and temperature profiles at 21 UT with a 3 km vertical wavelength that was much stronger in the vertical beam than in the north beam. The atmosphere appeared to become more active as the launch time approached. During the last interval with data, at ∼23:20 UT, Dec. 12th, the lidar profiles revealed a gravity wave in both beams with a magnitude of 5-10 K in temperature and approximately 5 km vertical wavelength. The large background shear plus the wave perturbation produced regions with potential convective instability at multiple altitudes. Copyright © The Society of Geomagnetism and Earth, Planetary and Space Sciences (SGEPSS); The Seismological Society of Japan; The Volcanological Society of Japan; The Geodetic Society of Japan; The Japanese Society for Planetary Sciences; TERRAPUB.
  • Yoshiharu Omura, Takumi Abe, Gurbax S. Lakhina, Satonori Nozawa, Yukihiro Takahashi, Eivind Thrane, Yoav Yair
    Earth, Planets and Space 58(9) 1105 2006年  査読有り
  • Yoshiharu Omura, Takumi Abe, Gurbax Lakhina, Satonori Nozawa, Yukihiro Takahashi, Eivind Thrane, Yoav Yair
    EARTH PLANETS AND SPACE 58(9) 1105-1105 2006年  査読有り
  • Takumi Abe, Koh Ichiro Oyama, Akihiro Kadohata
    Earth, Planets and Space 58(9) 1139-1146 2006年  査読有り
    Japanese sounding rocket "S-310-35" was launched from Andoya Rocket Range in Norway on December 13, 2004 during Dynamics and Energetics of the Lower Thermosphere in Aurora (DELTA) campaign, in which the rocket-borne in-situ measurements and ground-based measurements were coordinated to conduct a comprehensive observation of the upper atmospheric response against the auroral energy input. The Fast Langmuir Probe (FLP) was installed on the sounding rocket to study thermal structure and energy balance of the plasma by measuring the electron temperature in the polar lower ionosphere. The FLP observations indicate that the electron temperatures were found to be remarkably high in an altitude range from 106 km to 114 km during the ascending phase of the rocket. The lowest part of this high temperature region might be affected by artificial electron beam which was generated by the N-2 temperature instrument on the same rocket. On the other hand, a small increase of the electron temperature was observed at the altitude from 114 to 119 km in the descending phase. This is possibly the first time that both the temperature increase and density fluctuation that may be caused by the Farley-Buneman instability were detected by in-situ observation.
  • Eoghan Griffin, Mike Kosch, Anasuya Aruliah, Andrew Kavanagh, Ian McWhirter, Andrew Senior, Elaina Ford, Chris Davis, Takumi Abe, Junichi Kurihara, Kirsti Kauristie, Yasunobu Ogawa
    Earth, Planets and Space 58(9) 1113-1121 2006年  査読有り
    The Japan Aerospace Exploration Agency (JAXA) DELTA rocket experiment, successfully launched from Andoya at 0033 UT on December 13, 2004, supported by ground based optical instruments, primarily 2 Fabry-Perot Interferometers (FPIs) located at Skibotn, Norway (69.3 degrees N, 20.4 degrees E) and the KEOPS Site, Esrange, Kiruna, Sweden (67.8 degrees N, 20.4 degrees E). Both these instruments sampled the 557.7 nm lower thermosphere atomic oxygen emission and provided neutral temperatures and line-of-sight wind velocities, with deduced vector wind patterns over each site. All sky cameras allow contextual auroral information to be acquired. The proximity of the sites provided overlapping fields of view, adjacent to the trajectory of the DELTA rocket. This allowed independent verification of the absolute temperatures in the relatively quiet conditions early in the night, especially important given the context provided by co-located EISCAT ion temperature measurements which allow investigation of the likely emission altitude of the passive FPI measurements. The results demonstrate that this altitude changes from 120 km pre-midnight to 115 km post-midnight. Within this large scale context the results from the FPIs also demonstrate smaller scale structure in neutral temperatures, winds and intensities consistent with localised heating. These results present a challenge to the representation of thermospheric variability for the existing models of the region.
  • Junichi Kurihara, Takumi Abe, Koh Ichiro Oyama, Eoghan Griffin, Mike Kosch, Anasuya Aruliah, Kirsti Kauristie, Yasunobu Ogawa, Sayaka Komada, Naomoto Iwagami
    Earth, Planets and Space 58(9) 1123-1130 2006年  査読有り
    The rotational temperature and number density of molecular nitrogen (N(2)) in the lower thermosphere were measured by the N2 temperature instrument onboard the S-310-35 sounding rocket, which was launched from Andoya at 0:33 UT on 13 December 2004, during the Dynamics and Energetics of the Lower Thermosphere in Aurora (DELTA) campaign. The rotational temperature measured at altitudes between 95 and 140 km, which is expected to be equal to neutral temperature, is much higher than neutral temperature from the Mass Spectrometer Incoherent Scatter (MSIS) model. Neutral temperatures in the lower thermosphere were observed using the auroral green line at 557.7 nm by two Fabry-Perot Interferometers (FPIs) at Skibotn and the Kiruna Esrange Optical Platform System site. The neutral temperatures derived from the look directions closest to the rocket correspond to the rotational temperature measured at an altitude of 120 km. In addition, a combination of the all-sky camera images at 557.7 nm observed at two stations, Kilpisjarvi and Muonio, suggests that the effective altitude of the auroral arcs at the time of the launch is about 120 km. The FPI temperature observations are consistent with the in situ rocket observations rather than the MSIS model.
  • Takumi Abe, Junichi Kurihara, Naomoto Iwagami, Satonori Nozawa, Yasunobu Ogawa, Ryoichi Fujii, Hajime Hayakawa, Kon Ichiro Oyama
    Earth, Planets and Space 58(9) 1165-1171 2006年  査読有り
    Japanese sounding rocket "S-310-35" was launched from Andøya Rocket Range in Norway on December 13, 2004 during Dynamics and Energetics of the Lower Thermosphere in Aurora (DELTA) campaign, in which the rocket-borne in-situ measurements and ground-based measurements were coordinated to carry out a comprehensive observation of the thermospheric response against the auroral energy input. The instruments on board the rocket successfully performed their measurements during the flight, and thereby the temperature and density of molecular nitrogen, auroral emission rate, and the ambient plasma parameters were derived. Simultaneous measurements by the ground-based instruments provided neutral wind, neutral temperature, the auroral images and the ionospheric parameters near the rocket trajectory. This paper introduces science objectives, experimental outline, and preliminary scientific results of the DELTA campaign and explains geophysical condition at the time of the rocket launch, while the companion papers in this special issue describe more detailed results from each instrument. Copyright © The Society of Geomagnetism and Earth, Planetary and Space Sciences (SGEPSS); The Seismological Society of Japan; The Volcanological Society of Japan; The Geodetic Society of Japan; The Japanese Society for Planetary Sciences; TERRAPUB.
  • Nobuaki Ishii, Yoshifumi Inatani, Satoshi Nonaka, Takashi Nakajima, Abe Takumi, Tsuda Yuichi, Takamasa Yamagami
    European Space Agency, (Special Publication) ESA SP (590) 13-18 2005年  
    In October 2003, a new space agency, JAXA (Japan Aerospace Exploration Agency) was reorganized and started as a primary space agency to promote all space activities in Japan. The Institute of Space and Astronautical Science (ISAS) belonged to JAXA and continued to promote space science and technologies using unique scientific satellites, sounding rockets and balloons. This paper summarizes sounding rocket and ballooning activities of ISAS in the fiscal year of 2003 and 2004, associated with satellite launch programs. In this time period, three sounding rockets and nineteen balloons were launched by ISAS. One of the sounding rocket, S-310-35 was an international collaboration between Japan and Norway, which was launched from Andoya Rocket Range (ARR), Andenes, Norway, so as to study the upper atmospheric dynamics and energetics associated with the auroral energy in the polar lower thermosphere. Through the combination with the national researchers and the cooperation with international organizations, ISAS will keep its own flight opportunities and be able to obtain many new scientific findings.
  • Takumi Abe, Andrew W. Yau, Shigeto Watanabe, Manabu Yamada, Eiichi Sagawa
    Journal of Geophysical Research: Space Physics 109(9) 2004年  査読有り
    We present the solar activity dependence and seasonal variation of H+ and O+ polar wind velocity profiles observed by the suprathermal ion mass spectrometer (SMS) on Akebono. These observations spanned a solar cycle and covered a wide range of altitudes and invariant latitudes (ILAT) in the polar ionosphere and a variety of geomagnetic activity conditions from 1500 km to 8500 km altitude and from the poleward edge of the ionospheric trough (∼60° ILAT) to the polar cap (&gt 85° ILAT). At low (high) altitudes below (above) 4000 km, the increase of the averaged H+ and O+ ion velocities with altitude was larger (smaller) at solar minimum than at solar maximum. For example, the averaged H+ velocity on the dayside at 4000 km altitude was approximately 8 km s-1 at low solar activity but ∼5 km s-1 at high activity. This suggests that the averaged polar wind velocity correlates differently with solar activity and the dominant acceleration process may be different at low and high altitudes, respectively. For both H+ and O+ the observed ion velocity at high altitude was largest in the summer under essentially all magnetic and solar activity conditions. The O+ velocity at high altitude (&gt 4000 km) was significant and largest in the summer at solar maximum, when the solar energy input into the polar cap was largest theoretically, the velocity of O+ ions in the polar wind is expected to be negligible below 10,000 km. We consider geophysical processes that may contribute to the observed velocities and their solar activity and seasonal dependences, including the possible contributions of photoelectrons and elevated electron temperatures to the ambipolar electric field that drives the polar wind. Copyright 2004 by the American Geophysical Union.
  • Ivan Kutiev, Kohichiro Oyama, Takumi Abe
    Journal of Geophysical Research: Space Physics 107(12) 2002年  査読有り
    A new approach is used to reveal the average thermal structure of plasmasphere at altitudes between 1000 and 10,000 km. This paper only considers the plasmasphere inside L = 3, and this region of space is sliced at L = 2 to one internal (denoted as equatorial) and one external (denoted as midlatitude) part. Each of these parts is divided into four altitude/local time zones: northern and southern daytime and northern and southern nighttime. Electron temperature (Te) distribution measured along every individual orbit within each zone is approximated by simple expressions that are functions of the geomagnetic latitude or L. The fitting is performed independently to each zone, and two coefficients are extracted from the individual fits: Te value at the equatorward border and the coefficient scaling the latitudinal shape. These coefficients are accumulated in each zone in order to obtain its average Te structure as a function of altitude. The fitting coefficients exhibit large scatter, which reflects the large day-to-day variability of plasmasphere Te. The fitting error is estimated at 6% and 12% for the equatorial and midlatitude zones, respectively. The average fit coefficients are used to check for seasonal variations in each zone and for a possible hemispheric asymmetry. It is determined that the winter sunlit plasmasphere is hotter than the summer one the case for nighttime is reverse. The day/night amplitude is larger in the winter than in the summer, and the seasonal differences are more pronounced in the Southern Hemisphere. The latitude gradients of Te reveal a hemispheric asymmetry, which is largest during northern daytime winter. Solar activity is found to affect the plasmasphere Te. During the day at 3000 km and L = 2, Te increases by ∼ 2000°K when F10.7 changes from 70 to 300. The nighttime increase is ∼1000°K. At the equator, Te shows weaker dependence on solar activity. The average heat flux through 3000 km altitude is estimated at 3.7 × 109 (eV cm-2 s-1) during the day and 1.6 × 108 (eV cm-2 s -1) during the night. Copyright 2002 by the American Geophysical Union.
  • 小泉, 宜子, 下山, 学, 小山, 孝一郎, 村山, 泰啓, 橋元, 保雄, 下瀬, 滋, 長谷川, 克也, 鎌田, 幸男, 阿部, 琢美, Koizumi, Yoshiko, Shimoyama, Manabu, Oyama, Koh-ichiro, Murayama, Yasuhiro, Hashimoto, Yasuo, Shimose, Shigeru, Hasegawa, Katsuya, Kamata, Yukio, Abe, Takumi
    宇宙科学研究所報告. 特集: WAVE2000キャンペーン特集号: 下部熱圏縞々模様の解明 42 47-56 2001年3月  査読有り
    中間圏及び下部熱圏高度における中性大気の力学過程は電離気体と密接な関係があるため,この高度領域での中性風の測定は重要である.今までは米国製マイクロロケット(バイパーロケット)から放出されたフォイル・チャフをレーダーで追尾することにより,単独で中性風の測定を行っていた.そこで複数の地球物理的なパラメータと同時に中性風の測定を行えるよう,観測ロケットからフォイル・チャフを放出する機構の開発を行い,下記の二通りの放出機構を試した.1)フォイル・チャフを封入した円筒を大気圧封じし,高度約100kmでの圧力差により放出する方法2)フォイル・チャフを封入した縦に割れ目の入った円筒をバネの力で放出し,竹割りの要領でフォイル・チャフを散布する方法それぞれの円筒には約5,000枚のフォイル・チャフを封入でき,ロケット側面から放出を行う.2000年1月10日に打ち上げられた観測ロケットS-310-29号機にフォイル・チャフ放出機構を搭載し,打ち上げ341秒後のロケット下降時に合計約20,000枚のフォイル・チャフを放出することに成功した.フォイル・チャフは一次レーダーモードで高度約95.0-88.5kmの間で追尾され,レーダーの情報から中性風の風向・風速が得られた.
  • Yoshida, N, S. Watanabe, H. Fukunishi, T. Sakanoi, T. Abe, T. Mukai, H. Hayakawa, A. Matsuoka, Y. Kasahara, R. Fujii, S. Nozawa, Y. Ogawa
    Journal of Atmospheric and Terrestrial Physics 62(6) vol.. 62, iss. 6, p. 449-465-465 2000年  査読有り
  • A. W. Yau, T. Abe, M. J. Greffen, R. E. Horita, D. J. Knudsen, T. Mukai, K. I. Oyama, W. K. Peterson, E. Sagawa, S. Watanabe, B. A. Whalen
    Earth, Planets and Space 48(1) 45-56 1996年  
    We present an overview of direct ion and electron observations of the polar wind and suprathermal auroral ions from the plasma instruments on Akebono. In the polar wind, the observed H+ ion reaches a velocity of 1 km/s at 2000 km altitude, as does He+ ion near 3000 km and O+ ion near 6000 km. At high altitudes, the O+ ion constitutes a significant component of the polar wind flow contrary to most polar wind model predictions. At 2000-4000 km, the H+ ion velocity in the polar wind is strongly correlated with the ambient electron temperature. The electron temperature (averaged thermal energy) in the upward magnetic field direction is a factor of 1.5-2 higher than that in the downward and field-perpendicular directions. This results in an upward heat flux which is comparable in magnitude to the heat flux carried by energetic (&gt 10-eV) photoelectrons. The observed electron temperature anisotropy and correlation with ion velocity are consistent with the polar wind being driven by a large ambipolar electric field resulting from the presence of escaping atmospheric photoelectrons (required to maintain quasineutrality along the field line). At auroral latitudes, significant fluxes of "minor ions" are frequently observed, particularly atomic N+ and O++ ions and molecular NO+, N2+, and O2+ ions. The occurrence of molecular ions at high altitude (&gt 3000 km) during extended periods of auroral activity points to their fast energization at the F-region and topside ionosphere. In the 3000-6000 km altitude region, transverse ion energization occurs frequently both on the dayside and the nightside. Different ion species are energized in the perpendicular direction to tens and at times hundreds of eV over a narrow spatial extent, and appear as "ion conics" at higher altitudes as they spiral up the field lines. In the 3000-9000 km altitude region, the average energy of the observed ion conics in the dayside auroral zone increases with altitude.
  • T. Abe, S. Watanabe, B. A. Whalen, A. W. Yau, E. Sagawa
    Earth, Planets and Space 48(3) 319-325 1996年  
    We present a statistical analysis of thermal H+ and O+ ion flux measurements in the high-altitude (6000∼9000 km) polar ionosphere from the Suprathermal ion Mass Spectrometer (SMS) on Akebono. It is shown that the normalized H+ polar wind flux (to 2000 km altitude) varies from 107 to 108 cm-2s-1 at 2000 km altitudes. Surprisingly, the O+ ion flux is found to be comparable to the H+ ion flux and much higher than classical theory prediction. The magnetic local time (MLT) distribution of the upward ion flux and its geomagnetic activity (Kp) dependence are also presented. At both magnetically quiet and active times, the integrated H+ ion flux is largest in the noon sector (09∼15 MLT) and smallest in the midnight sector (21∼03 MLT) the flux ratio was found to be approximately one order of magnitude. The total flux of H+ ion outflow integrated over the polar ionosphere (ILAT ≥ 75°) and over all local times was found to correlate inversely with the Kp index. The integrated H+ flux (ILAT ≥ 75°) in quiet times was 0.9∼1.5 x 1025 ions s-1 while the flux in active times was a factor of 2∼3 smaller (0.4∼0.6 x 1025 ions s-1). It also exhibited a slight positive correlation with the IMF (interplanetary magnetic field) Bz component.
  • W. K. Peterson, T. Abe, H. Fukunishi, M. J. Greffen, H. Hayakawa, Y. Kasahara, I. Kimura, A. Matsuoka, T. Mukai, T. Nagatsuma, K. Tsuruda, B. A. Whalen, A. W. Yau
    Journal of Geophysical Research: Space Physics 99(12) 23257-23274 1994年  査読有り
    During geomagnetically active times, the suprathermal mass spectrometer on the Akebono satellite frequently observes upflowing molecular ions (NO +, N2 +, Û2*) in the 2-3 Earth radii geocentric distance regions in the auroral zone. Molecular ions originating at ionospheric altitudes must acquire an energy of the order of 10 eV in order to overcome gravitation and reach altitudes greater than 2 RE. This energy must be acquired in a time short compared with the local dissociative recombination lifetime of the ions the latter is of the order of minutes in the F region ionosphere (300-500 km altitude). Upflowing molecular ions thus provide a test particle probe into the mechanisms responsible for heavy ion escape from the ionosphere. In this paper we analyze the extensive complement of plasma, field, and wave data obtained on the Akebono satellite in a number of upflowing molecular ion events observed at high altitudes (5000 -10,000 km). We use these data to investigate the source of energization of the molecular ions at ionospheric altitudes. We show that Joule heating and ion resonance heating do not transfer enough energy or do not transfer it fast enough to account for the observed fluxes of upflowing molecular ions. We found that the observed field-aligned currents were too weak to support large-scale field-aligned current instabilities at ionospheric altitudes. The data suggest but in the absence of high-resolution wave measurements in the 300 to 500 km altitude range cannot ascertain the possibility that a significant fraction of escape energy is transferred to molecular ions in localized regions from intense plasma waves near the lower hybrid frequency. We also compared the energization of molecular ions to that of the geophysically important O+ ions in the 300 to 500 km altitude range, where the energy transfer to O+ is believed to occur via small-scale plasma instabilities, ion resonance, and ion-neutral factional heating. Direct observation of energy input to the ionosphere from all of these sources in combination with in situ measurements of the density and temperature of neutral and ionized oxygen in the 300 to 500 km range are required to determine the relative importance of these energy sources in providing O+ with sufficient energy to escape the ionosphere. Copyright © 1994 by the American Geophysical Union.

MISC

 326
  • 齊藤, 昭則, 松岡, 彩子, 坂崎, 貴俊, 阿部, 琢美, 齋藤, 義文, 石坂, 圭吾, 田川, 雅人, 横田, 久美子, 熊本, 篤志, 小嶋, 浩嗣, 栗田, 怜, 横山, 竜宏, 村田, 直史, 斎藤, 享, 高橋, 透, 西岡, 未知, 細川, 敬祐, 中田, 裕之, Huixin, Liu, 木暮, 優, 西山, 尚典, SAITO, Akinori, MATSUOKA, Ayako, SAKAZAKI, Takatoshi, ABE, Takumi, SAITO, Yoshifumi, ISHISAKA, Keigo, TAGAWA, Masahito, YOKOTA, Kumiko, KUMAMOTO, Atsushi, KOJIMA, Hirotsugu, KURITA, Satoshi, YOKOYAMA, Tatsuhiro, MURATA, Naofumi, SAITO, Susumu, TAKAHASHI, Toru, NISHIOKA, Michi, HOSOKAWA, Keisuke, NAKATA, Hiroyuki, HUIXIN, Liu, KOGURE, Masaru, NISHIYAMA, Takanori
    観測ロケットシンポジウム2022 講演集 = Proceedings of Sounding Rocket Symposium 2022 2023年3月  
    第5回観測ロケットシンポジウム(2023年2月28日-3月1日. オンライン開催) 5th Sounding Rocket Symposium(February 28-March 1, 2023. Online Meeting) 著者人数: 21名 資料番号: SA6000185020 レポート番号: Ⅲ-5
  • 足立, 泰雅, 平, 翔馬, 加藤, 大志, 下位, 百香, 熱田, 凛太朗, 山下, 裕介, 小澤, 宇志, 中山, 宜典, 飛田, 奈々美, 阿部, 琢美, 横田, 久美子, 田川, 雅人, ADACHI, Taiga, TAIRA, Shoma, KATO, Taishi, SHIMOI, Momoka, ATSUTA, Rintaro, YAMASHITA, Yusuke, OZAWA, Takashi, NAKAYAMA, Yoshinori, TOBITA, Nanami, ABE, Takumi, YOKOTA, Kumiko, TAGAWA, Masahito
    観測ロケットシンポジウム2022 講演集 = Proceedings of Sounding Rocket Symposium 2022 2023年3月  
    第5回観測ロケットシンポジウム(2023年2月28日-3月1日. オンライン開催) 5th Sounding Rocket Symposium(February 28-March 1, 2023. Online Meeting) 著者人数: 12名 資料番号: SA6000185005 レポート番号: Ⅰ-5
  • 齊藤, 昭則, 坂崎, 貴俊, 阿部, 琢美, 横山, 竜宏, 西山, 尚典, 高橋, 透, SAITO, Akinori, SAKAZAKI, Takatoshi, ABE, Takumi, YOKOYAMA, Tatsuhiro, NISHIYAMA, Noritoshi, TAKAHASHI, Toru
    観測ロケットシンポジウム2022 講演集 = Proceedings of Sounding Rocket Symposium 2022 2023年3月  
    第5回観測ロケットシンポジウム(2023年2月28日-3月1日. オンライン開催) 5th Sounding Rocket Symposium(February 28-March 1, 2023. Online Meeting) 資料番号: SA6000185032 レポート番号: Ⅵ-4
  • 田中, 真, 松岡, 彩子, 野村, 麗子, 阿部, 琢美, TANAKA, Makoto, MATSUOKA, Ayako, NOMURA, Reiko, ABE, Takumi
    観測ロケットシンポジウム2022 講演集 = Proceedings of Sounding Rocket Symposium 2022 2023年3月  
    第5回観測ロケットシンポジウム(2023年2月28日-3月1日. オンライン開催) 5th Sounding Rocket Symposium(February 28-March 1, 2023. Online Meeting) 資料番号: SA6000185006 レポート番号: Ⅰ-6
  • 松山, 実由規, 石坂, 圭吾, 芦原, 佑樹, 山本, 衛, 熊本, 篤志, 白澤, 秀剛, 阿部, 琢美, MATSUYAMA, Miyuki, ISHIZAKA, Keigo, ASHIHARA, Yuki, YAMAMOTO, Mamoru, KUMAMOTO, Atsushi, SHIRAKAWA, Hidetaka, ABE, Takumi
    観測ロケットシンポジウム2022 講演集 = Proceedings of Sounding Rocket Symposium 2022 2023年3月  
    第5回観測ロケットシンポジウム(2023年2月28日-3月1日. オンライン開催) 5th Sounding Rocket Symposium(February 28-March 1, 2023. Online Meeting) 資料番号: SA6000185003 レポート番号: Ⅰ-3

書籍等出版物

 2

講演・口頭発表等

 111

担当経験のある科目(授業)

 1

共同研究・競争的資金等の研究課題

 14

● 指導学生等の数

 2
  • 年度
    2021年度(FY2021)
    修士課程学生数
    4
    受託指導学生数
    4
    技術習得生の数
    1
  • 年度
    2020年度(FY2020)
    修士課程学生数
    3
    受託指導学生数
    3
    技術習得生の数
    2

● 専任大学名

 1
  • 専任大学名
    総合研究大学院大学(SOKENDAI)

● 所属する所内委員会

 3
  • 所内委員会名
    理学委員会
  • 所内委員会名
    観測ロケット専門委員会
  • 所内委員会名
    スペースチェンバー専門委員会