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MORIMOTO Takeshi

    Department of Electrical, Electronic and Communication Engineering　Professor
Last Updated :2024/04/25

Researcher Information

URL

Research funding number

  • 60403169

ORCID ID

J-Global ID

Research Interests

  • Remote Sensing   lightning discharge   環境電磁工学   大気電気学   

Research Areas

  • Manufacturing technology (mechanical, electrical/electronic, chemical engineering) / Electrical power engineering
  • Natural sciences / Atmospheric and hydrospheric science
  • Manufacturing technology (mechanical, electrical/electronic, chemical engineering) / Measurement engineering

Academic & Professional Experience

  • 2022/04 - Today  Kindai UniversityDepartment of Electric, Electronic and Communication Engineering, Faculty of Science and EngineeringProfessor
  • 2019/04 - 2022/03  Kindai UniversityDepartment of Electric and Electronic Engineering, Faculty of Science and EngineeringProfessor

Association Memberships

  • THE REMOTE SENSING SOCIETY OF JAPAN   Meteorological Society of Japan   American Geophysical Union   Society of Atmospheric Electricity of Japan   The Institute of Electrical Engineers of Japan   

Published Papers

  • Y. Wada; T. Wu; D. Wang; T. Enoto; K. Nakazawa; T. Morimoto; Y. Nakamura; T. Shinoda; H. Tsuchiya
    Journal of Geophysical Research: Atmospheres American Geophysical Union (AGU) 2169-897X 2023/07 [Refereed]
  • M. Tsurumi; T. Enoto; Y. Ikkatai; T. Wu; D. Wang; T. Shinoda; K. Nakazawa; N. Tsuji; G. S. Diniz; J. Kataoka; N. Koshikawa; R. Iwashita; M. Kamogawa; T. Takagaki; S. Miyake; D. Tomioka; T. Morimoto; Y. Nakamura; H. Tsuchiya
    Geophysical Research Letters American Geophysical Union (AGU) 50 (13) 0094-8276 2023/07 [Refereed]
  • Y. Wada; T. Morimoto; Y. Nakamura; T. Wu; T. Enoto; K. Nakazawa; T. Ushio; T. Yuasa; H. Tsuchiya
    Geophysical Research Letters American Geophysical Union (AGU) 49 (5) 0094-8276 2022/03 [Refereed]
  • S. Hisadomi; K. Nakazawa; Y. Wada; Y. Tsuji; T. Enoto; T. Shinoda; T. Morimoto; Y. Nakamura; T. Yuasa; H. Tsuchiya
    Journal of Geophysical Research: Atmospheres American Geophysical Union (AGU) 126 (18) 2169-897X 2021/09 [Refereed]
     
    Around 17:00 on January 12, 2020 (UTC), radiation detectors installed at two locations with a 1.35 km separation in Kanazawa City, Japan, captured a total of four gamma-ray enhancements. The first pair was simultaneously observed at the two locations at 17:03 and were abruptly terminated by a lightning discharge. The remaining two enhancements were also nearly simultaneously observed similar to 3 min later, and one of them was also terminated by another lightning discharge. At the last termination, a downward terrestrial gamma-ray flash and a negative energetic in-cloud pulse were observed. Both pairs were associated with thundercloud cells. In the first pair, simultaneous detection in two locations 1.35 km apart suggests either a gamma-ray glow emerged in-between and time variability of its intensity were directly observed or there were two (or more) gamma-ray glows in the cell which reached the two detectors coincidentally. In the latter pair, the peak time in the downwind detector was similar to 40 s later than that of the upwind detector. If the irradiation region moved with the cell, it would have taken similar to 110 s. The discrepancy suggests either the glow moved 2.5 times faster than the cell or there were two (or more) glows in the cell. Also, the fact that the thunderstorm cell hosting the latter glows experienced the lightning discharge similar to 3 min before suggests that the strong electric field in the cell can develop within a few minutes.
  • Daiki Nozawa; Takeshi Morimoto; Keitaro Asai; Yoshitaka Nakamura; Tomoo Ushio
    Journal of Atmospheric Electricity Institute of Electrical Engineers of Japan (IEE Japan) 39 (1) 42 - 45 0919-2050 2020/10 [Refereed]
  • Kosuke Tomita; Takeshi Morimoto; Hiroki Motoyoshi; Yoshitaka Nakamura; Hideo Sakai
    Journal of Atmospheric Electricity Institute of Electrical Engineers of Japan (IEE Japan) 39 (1) 33 - 36 0919-2050 2020/10 [Refereed]
  • Y. Wada; T. Enoto; Y. Nakamura; T. Morimoto; M. Sato; T. Ushio; K. Nakazawa; T. Yuasa; D. Yonetoku; T. Sawano; M. Kamogawa; H. Sakai; Y. Furuta; K. Makishima; H. Tsuchiya
    Journal of Geophysical Research: Atmospheres American Geophysical Union ({AGU}) 125 (4) 2169-897X 2020/02 [Refereed]
     
    ©2020. American Geophysical Union. All Rights Reserved. During 2017–2018 winter operation of the Gamma-Ray Observation of Winter Thunderclouds experiment in Japan, two downward terrestrial gamma-ray flashes (TGFs) that triggered atmospheric photonuclear reactions were detected. They took place during winter thunderstorms on 5 December 2017 and 9 January 2018 at Kanazawa, Ishikawa Prefecture, Japan. Each event coincided with an intracloud/intercloud discharge, which had a negative-polarity peak current higher than 150 kA. Their radio waveforms in the low-frequency band are categorized as a distinct lightning type called “energetic in-cloud pulse” (EIP). Negative-polarity EIPs have been previously suggested to be highly associated with downward TGFs, and the present observations provide evidence of the correlation between them for the first time. Furthermore, both of the downward TGFs followed “gamma-ray glows,” minute-lasting high-energy emissions from thunderclouds. It is suggested that the negative EIPs took place with downward propagating negative leaders or upward positive ones developed in highly electrified regions responsible for the gamma-ray glows.
  • Yuuki Wada; Teruaki Enoto; Yoshitaka Nakamura; Yoshihiro Furuta; Takayuki Yuasa; Kazuhiro Nakazawa; Takeshi Morimoto; Mitsuteru Sato; Takahiro Matsumoto; Daisuke Yonetoku; Tatsuya Sawano; Hideo Sakai; Masashi Kamogawa; Tomoo Ushio; Kazuo Makishima; Harufumi Tsuchiya
    Communications Physics 2 (1) 2399-3650 2019/12 [Refereed]
     
    © 2019, The Author(s). Two types of high-energy events have been detected from thunderstorms. One is “terrestrial gamma-ray flashes” (TGFs), sub-millisecond emissions coinciding with lightning discharges. The other is minute-lasting “gamma-ray glows”. Although both phenomena are thought to originate from relativistic runaway electron avalanches in strong electric fields, the connection between them is not well understood. Here we report unequivocal simultaneous detection of a gamma-ray glow termination and a downward TGF, observed from the ground. During a winter thunderstorm in Japan on 9 January 2018, our detectors caught a gamma-ray glow, which moved for ~100 s with ambient wind, and then abruptly ceased with a lightning discharge. Simultaneously, the detectors observed photonuclear reactions triggered by a downward TGF, whose radio pulse was located within ~1 km from where the glow ceased. It is suggested that the highly-electrified region producing the glow was related to the initiation of the downward TGF.
  • Y.Wada; T.Enoto; K.Nakazawa; Y.Furuta; T.Yuasa; Y.Nakamura; T.Morimoto; T.Matsumoto; K.Makishima; H.Tsuchiya
    Physical Review Letters American Physical Society (APS) 123 (6) 1079-7114 2019/08 [Refereed]
  • Y. Wada; G. S. Bowers; T. Enoto; M. Kamogawa; Y. Nakamura; T. Morimoto; D. M. Smith; Y. Furuta; K. Nakazawa; T. Yuasa; A. Matsuki; M. Kubo; T. Tamagawa; K. Makishima; H. Tsuchiya
    Geophysical Research Letters Blackwell Publishing Ltd 45 (11) 5700 - 5707 1944-8007 2018/06 [Refereed]
     
    An on-ground observation program for high-energy atmospheric phenomena in winter thunderstorms along the Japan Sea has been performed via measurements of gamma ray radiation, atmospheric electric field, and low-frequency radio band. On 11 February 2017, the radiation detectors recorded gamma ray emission lasting for 75 s, and then abruptly terminated with a nearby lightning discharge. The gamma ray spectrum extended up to 20 MeV and was reproduced by a cutoff power law model with a photon index of 1.36+0.03−0.04, being consistent with Bremsstrahlung radiation from a thundercloud (known as a gamma-ray glow or a thunderstorm ground enhancement). The low-frequency radio monitors, installed ∼50 km away from the gamma ray observation site recorded leader development of an intracloud/intercloud discharge spreading over ∼60 km area with a ∼300-ms duration. The timing of the gamma ray termination coincided with the moment when the leader development of the intracloud/intercloud discharge passed 0.7 km horizontally away from the radiation monitors. The intracloud/intercloud discharge started ∼15 km away from the gamma ray observation site. Therefore, the glow was terminated by the leader development, while it did not trigger the lightning discharge in the present case.
  • Mitsuteru Sato; Toru Adachi; Tomoo Ushio; Takeshi Morimoto; Masayuki Kikuchi; Hiroshi Kikuchi; Makoto Suzuki; Atsushi Yamazaki; Yukihiro Takahashi; Ryohei Ishida; Yuji Sakamoto; Kazuya Yoshida; Yasuhide Hobara
    TERRESTRIAL ATMOSPHERIC AND OCEANIC SCIENCES CHINESE GEOSCIENCE UNION 28 (4) 545 - 561 1017-0839 2017/08 [Refereed]
     
    The Global Lightning and Sprite Measurements on the Japanese Experiment Module (JEM-GLIMS) started continuous nadir observations of lightning and transient luminous events (TLEs) at the International Space Station (ISS) in November 2012 and completed the observations in August 2015. As JEM-GLIMS uses the nadir observation technique, the JEM-GLIMS optical instruments simultaneously measure both incomparably intense lightning emissions and weak sprite emissions. We adopted combined data analytical methods to distinguish between these two types of emissions: (1) a subtraction of the wideband LSI-1 image from the narrowband LSI-2 image, (2) a calculation of the intensity ratio between different photometer channels, and (3) an estimation of the charge moment change (CMC) of the suspected sprite-producing CG discharge. This report presents as a case study one sprite event detected at 19: 50: 40.30580 UT on 28 September 2013 and identified using the above analytical methods. From the results derived from detailed data analyses, we judged that the optical emission measured by LSI-2 is a sprite emission. We carried out the geometry conversion toward the LSI-1 and subtracted images and found that the sprite emission location shifts by 3.5 km from the peak lightning emission location, which agree with the previous reports. The detailed horizontal distributions of sprites and the relationship between the sprite location and the parent lightning location are quantitatively revealed for the first time.
  • T.Morimoto; H.Kikuchi; S.Yoshida; T.Ushio; Z.-I.Kawasaki
    Journal of Atmospheric Electricity Society of Atmospheric Electricity of Japan 36 (2) 39 - 53 2017/03 [Refereed]
  • Hiroshi Kikuchi; Mitsuteru Sato; Tomoo Ushio; Takeshi Morimoto; Masayuki Kikuchi; Atsushi Yamazaki; Makoto Suzuki; Ryohei Ishida; Yuji Sakamoto; Ting Wu; Zen Kawasaki
    GEOPHYSICAL RESEARCH LETTERS AMER GEOPHYSICAL UNION 44 (2) 1123 - 1131 0094-8276 2017/01 [Refereed]
     
    Observations of optical lightning data with a photometer (PH4) at wavelengths of 599-900nm on the International Space Station were conducted simultaneously with observations of low-frequency (LF) electromagnetic waves with a ground-based LF lightning locating system. The relationship between the PH4 light curve and electromagnetic waveforms in the LF band was examined for 11 lightning events. The PH4 sensor detected a small optical change even for weak light emitted from lightning discharges in clouds, including preliminary breakdown. Particularly, return strokes, including subsequent return strokes, showed a clear relationship between radiated LF waves and optical waveforms. For negative return strokes, we found a clear correlation between the absolute optical intensity and peak current. The slope of the regression line is 9.7x10(-8)kAW(-1) with an intercept of 9.9kA.
  • Identification of sprites in JEM-GLIMS nadir observations and their spatial distributions
    M. Sato; T. Adachi; T. Ushio; T. Morimoto; M. Kikuchi; H. Kikuchi; M. Suzuki; A. Yamazaki; Y. Takahashi; R. Ishida; Y. Sakamoto; K. Yoshida; Y. Hobara
    Terrestrial, Atmospheric and Oceanic Sciences (TAO), accepted 21 Sep. 2016. 2016/09 [Refereed]
  • Takeshi Morimoto; Hiroshi Kikuchi; Mitsuteru Sato; Tomoo Ushio; Atsushi Yamazaki; Makoto Suzuki; Ryohei Ishida; Yuji Sakamoto; Kazuya Yoshida; Yasuhide Hobara; Takuki Sano; Takumi Abe; Zen-Ichiro Kawasaki
    EARTH PLANETS AND SPACE SPRINGER HEIDELBERG 68 (145) 1880-5981 2016/08 [Refereed]
     
    The Global Lightning and sprIte MeasurementS (GLIMS) mission has been conducted at the Exposed Facility of Japanese Experiment Module (JEM-EF) of the International Space Station for more than 30 months. This paper focuses on an electromagnetic (EM) payload of JEM-GLIMS mission, the very high frequency (VHF) broadband digital InTer-Ferometer (VITF). The JEM-GLIMS mission is designed to conduct comprehensive observations with both EM and optical payloads for lightning activities and related transient luminous events. Its nominal operation continued from November 2012 to December 2014. The extended operation followed for eight months. Through the operation period, the VITF collected more than two million VHF EM waveforms in almost 18,700 datasets. The number of VITF observations synchronized with optical signal is 8049. Active VHF radiations are detected in about 70 % of optical observations without obvious regional or seasonal dependency. Estimations of the EM direction-of-arrival (DOA) are attempted using the broadband digital interferometry. Some results agree with the optical observations, even though DOA estimation is problematic because of a very short antenna baseline and multiple pulses over a short time period, namely burst-type EM waveforms. The world's first lightning observations by means of space-borne VHF interferometry are achieved in this mission. This paper summarizes VITF instruments, the recorded VHF EM signals, and the results of DOA estimations by means of digital interferometry as a preliminary report after termination of the mission.
  • Hiroshi Kikuchi; Takeshi Morimoto; Mitsuteru Sato; Tomoo Ushio; Masayuki Kikuchi; Atsushi Yamazaki; Makoto Suzuki; Ryohei Ishida; Yuji Sakamoto; Zen Kawasaki
    IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC 54 (7) 3868 - 3877 0196-2892 2016/07 [Refereed]
     
    We report an initial investigation of the new location method of a very high frequency (VHF) radiation source, using signals recorded at the International Space Station. A VHF interferometer (VITF) has two VHF sensors. Locating lightning with VHF bands is useful to locate the position of the charge distribution in the thunderstorm. The location method of a radio source proposed used two direction-of-arrival estimation techniques. One is the interferometric technique, and another is based on the ionospheric propagation delay measurement of received signals. The combination of the two techniques provides two angular positions of the radiation source. When an altitude of a radiation source is assumed, we can determine two possible positions. One of the two positions was associated with the radiation source, while the other was not. In this paper, we compared the position of lightning and sprite imager (LSI) data, which are simultaneously captured during a lightning emission, with the locating position near the emission. The data set of the VITF within 100 ms of the optical lightning emission captured with the LSI was used. The temporally simultaneous event seems to be associated with the same lightning event. The estimated radiation positions were spatially in close agreement with the optical lightning positions captured with LSI, under nighttime ionosphere conditions. From statistical analysis, the spatial difference of the standard deviation changed from 15.3 to 30.8 km depending on the installation direction of the VHF sensors. The usefulness and limitations of the method are also discussed.
  • M. Sato; M. Mihara; T. Adachi; T. Ushio; T. Morimoto; M. Kikuchi; H. Kikuchi; M. Suzuki; A. Yamazaki; Y. Takahashi; U. Inan; I. Linscott; R. Ishida; Y. Sakamoto; K. Yoshida; Y. Hobara
    JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES AMER GEOPHYSICAL UNION 121 (7) 3171 - 3194 2169-897X 2016/04 [Refereed]
     
    Global Lightning and Sprite Measurements on Japanese Experiment Module (JEM-GLIMS) started the nadir observations of lightning discharges and transient luminous events (TLEs) from the International Space Station (ISS) since November 2012. In the nadir observations, JEM-GLIMS optical instruments have to simultaneously detect incomparably intense lightning emissions and weak TLE emissions. To distinguish TLEs, especially sprite events, from lightning events, combined data analytical methods are adopted: (1) a subtraction of the wideband camera image from the narrowband camera image, (2) a calculation of the intensity ratio between different photometer channels, and (3) an estimation of the polarization and charge moment changes for the TLE-producing lightning discharges. We succeeded in identifying numbers of sprite events using the combined analytical methods, and here we report three sprite events detected by JEM-GLIMS as a case study. In the subtracted images, sprite emissions are located over the area of the sprite-producing lightning emissions. However, these sprites and sprite-producing lightning discharges did not occur at the nadir point of the ISS. For this reason, the geometry conversion of the sprite and sprite-producing lightning emissions as observed from the point just over the sprite-producing lightning discharges is performed. In the geometry-converted images, the locations of the sprite emissions are clearly displaced by 8-20km from the peak positions of the sprite-producing lightning emissions. Thus, the first quantitative spatial distributions of sprites and sprite-producing lightning discharges from the JEM-GLIMS nadir observations are revealed.
  • M. Sato; T. Ushio; T. Morimoto; M. Kikuchi; H. Kikuchi; T. Adachi; M. Suzuki; A. Yamazaki; Y. Takahashi; U. Inan; I. Linscott; R. Ishida; Y. Sakamoto; K. Yoshida; Y. Hobara; T. Sano; T. Abe; M. Nakamura; H. Oda; Z. -I. Kawasaki
    JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES AMER GEOPHYSICAL UNION 120 (9) 3822 - 3851 2169-897X 2015/05 [Refereed]
     
    Global Lightning and Sprite Measurements on Japanese Experiment Module (JEM-GLIMS) is a space mission to conduct the nadir observations of lightning discharges and transient luminous events (TLEs). The main objectives of this mission are to identify the horizontal distribution of TLEs and to solve the occurrence conditions determining the spatial distribution. JEM-GLIMS was successfully launched and started continuous nadir observations in 2012. The global distribution of the detected lightning events shows that most of the events occurred over continental regions in the local summer hemisphere. In some events, strong far-ultraviolet emissions have been simultaneously detected with N-2 1P and 2P emissions by the spectrophotometers, which strongly suggest the occurrence of TLEs. Especially, in some of these events, no significant optical emission was measured by the narrowband filter camera, which suggests the occurrence of elves, not sprites. The VLF receiver also succeeded in detecting lightning whistlers, which show clear falling-tone frequency dispersion. Based on the optical data, the time delay from the detected lightning emission to the whistlers was identified as approximate to 10ms, which can be reasonably explained by the wave propagation with the group velocity of whistlers. The VHF interferometer conducted the spaceborne interferometric observations and succeeded in detecting VHF pulses. We observed that the VHF pulses are likely to be excited by the lightning discharge possibly related with in-cloud discharges and measured with the JEM-GLIMS optical instruments. Thus, JEM-GLIMS provides the first full set of optical and electromagnetic data of lightning and TLEs obtained by nadir observations from space.
  • Hiroshi Kikuchi; Tomoo Ushio; Mitsuteru Sato; Takeshi Morimoto; Atsushi Yamazaki; Makoto Suzuki
    IEEE International Symposium on Electromagnetic Compatibility 2014-December 398 - 401 1077-4076 2014/12 [Refereed]
     
    © 2014 The Institute of Electronics, Information and Communication Engineer. Since 2012, the global lightning and sprite measurements (GLIMS) mission has been conducted on the exposed facility of Japanese experiment module (JEM-EF) of the international space station (ISS). In this mission, the VHF broadband digital interferometer (VITF) attached on JEM-EF is designed to estimate the direction of arrival of electromagnetic waves. The VITF has the bandwidth from 70 MHz to 100 MHz. The electromagnetic radiations from lightning discharges received by two antennas are digitized by the 2-channel AD converter. We introduce the outline of the mission and the VITF. The initial observational results with the VITF of the GLIMS mission are presented. The comparison of the results of arrival direction estimation of the VITF with optical observations using two methods which are an interferometry technic and the group delay characteristic of EM waves. The results agree with the position of the lightning emission captured by the LSI.
  • Hiroshi Kikuchi; Takeshi Morimoto; Tomoo Ushio; Mitsuteru Sato; Atsushi Yamazaki; Makoto Suzuki
    International Conference on Atmospheric Electricity, ICAE 2014 2014 [Refereed]
     
    © International Conference on Atmospheric Electricity, ICAE 2014 We has been conducted the lightning observation with four type sensors at the International Space Station (ISS). One of the sensors is very high frequency interferometer: VITF. The objective of the VITF is to locate the radiation source of received signals with two very high frequency interferometer (VHF) sensors attached on the ISS. Lightning and sprite imager: LSI is also one of the optical sensor for the observation of lightning and sprite. The LSI consists of two CMOS sensors. The image captured with the LSI gives us an information of lighting position. While the VITF has the two sensors. Although the VITF is able to estimate the direction of arrival estimation using the radio interferometric technique, we cannot locate the radiation source position. The location method are used as two direction of arrival (DOA) estimation techniques, which are the interferometric technique and based on the measurement of the group delay of the received signals. The combination of the two techniques gives us the two possible position of the radiation source when an altitude of a radiation source is assumed. The initial comparison with the optical lightning position captured with LSI are reported.
  • Hiroshi Kikuchi; Tomoo Ushio; Takeshi Morimoto; Mitsuteru Sato; Atsushi Yamazaki; Makoto Suzuki
    2014 INTERNATIONAL SYMPOSIUM ON ELECTROMAGNETIC COMPATIBILITY, TOKYO (EMC'14/TOKYO) IEEE 398 - 401 2158-110X 2014 [Refereed]
     
    Since 2012, the global lightning and sprite measurements (GLIMS) mission has been conducted on the exposed facility of Japanese experiment module (JEM-EF) of the international space station (ISS). In this mission, the VHF broadband digital interferometer (VITF) attached on JEM-EF is designed to estimate the direction of arrival of electromagnetic waves. The VITF has the bandwidth from 70 MHz to 100 MHz. The electromagnetic radiations from lightning discharges received by two antennas are digitized by the 2-channel AD converter. We introduce the outline of the mission and the VITF. The initial observational results with the VITF of the GLIMS mission are presented. The comparison of the results of arrival direction estimation of the VITF with optical observations using two methods which are an interferometry technic and the group delay characteristic of EM waves. The results agree with the position of the lightning emission captured by the LSI.
  • Tomoo Ushio; Mitsuteru Sato; Takeshi Morimoto; Hiroshi Kikuchi; Makoto Suzuki; Atsushi Yamazaki; Yasuhide Hobara; Toru Adachi
    2014 XXXITH URSI GENERAL ASSEMBLY AND SCIENTIFIC SYMPOSIUM (URSI GASS) IEEE 2014 [Refereed]
     
    The Global Lightning and sprIte MeasurementS (GLIMS) on the International Space Station (ISS) is a mission to detect and locate optical transient luminous events (TLEs) and its associated lightning simultaneously from the non-sun synchronous orbit, and is scheduled to be launch from Japan in January, 2012 as part of the multi-mission consolidated equipment on Japanese Exposure Module (JEM). Our mission goals are (1) to detect and locate lightning and sprite within storm scale resolution over a large region of the Earth's surface along the orbital track of the ISS without any bias, (2) to clarify the generation mechanism of sprite, and (3) to identify the occurrence conditions of TLEs. To achieve these goals, two CMOS cameras, six Photometers, VLF receiver, and VHF interferometer with two antennas, are installed at the bottom of the module to observe the TLEs as well as causative lighting discharges at nadir direction during day and night time. Though the luminous events so-called sprite, elves and jets have been investigated by numerous researchers all over the world based mainly on the ground observations, some important problems have not been fully understood yet such as generation mechanisms of columniform fine structure and horizontal offset of some sprites from the parent lightning discharges. In the JEM-GLIMS mission, observations from our synchronized sensors are going to shed light on above-mentioned unsolved problems regarding TLEs as well as causative lighting discharges. In this presentation, the scientific background, instrumentation, project summaries and initial observation results are given.
  • Yuji Takayanagi; Manabu Akita; Yoshitaka Nakamura; Satoru Yoshida; Takeshi Morimoto; Tomoo Ushio; Zen Ichiro Kawasaki; Kenji Yamamoto
    Electrical Engineering in Japan (English translation of Denki Gakkai Ronbunshi) 185 (4) 9 - 17 0424-7760 2013/12 [Refereed]
     
    Summary We have been developing an EM source location system using the VLF/LF bands based on broadband digital interferometry to monitor lightning activity in a wide area. Since EM waves in VLF/LF radiated by lightning discharges propagate a long distance, the VLF/LF interferometer locates lightning discharges a few hundred kilometers away from the VLF/LF interferometer. We conducted a lightning observation campaign using a prototype of a VLF/LF band digital interferometer and VHF band digital interferometers in Darwin, Australia. The VLF/LF radiation sources were located near those of the VHF source. We succeeded in locating the VLF/LF radiation sources associated with return strokes near the ground. © 2013 Wiley Periodicals, Inc. Electr Eng Jpn, 185(4): 9-17, 2013; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/eej.22300 Copyright © 2013 Wiley Periodicals, Inc.
  • Ting Wu; Yuji Takayanagi; Tsuyoshi Funaki; Satoru Yoshida; Tomoo Ushio; Zen-Ichiro Kawasaki; Takeshi Morimoto; Masahito Shimizu
    JOURNAL OF ATMOSPHERIC AND SOLAR-TERRESTRIAL PHYSICS PERGAMON-ELSEVIER SCIENCE LTD 102 91 - 98 1364-6826 2013/09 [Refereed]
     
    Preliminary breakdown pulses (PBP) of 26 positive and 104 negative cloud-to-ground (CG) lightning flashes observed in winter thunderstorms in Hokuriku region of Japan are analyzed. Pulses in PBP train are mainly bipolar. Zero-crossing time of each pulse is about 7 us and total duration of each pulse train is about 1 ms. PBPs in negative CG lightning are classified as "BIL type" (59 cases) and "BL type" (45 cases). "BIL type" PBP contains an intermediate stage with little electric field changes. The time interval between PBP and the first return stroke (PBP-RS interval) is on average 5.4 ms for "BIL type" PBP, while that for "BL type" PBP is only 13 ms. Ratio of peak amplitude of PBP to the first return stroke (PBP-RS ratio) is on average 0.47 and 0.44, respectively, for "BIL type" and "BL type" PBPs, but the ratio for "BIL type" PBP has a much wider distribution. It is speculated that the intermediate stage in "BIL type" PBP is caused by horizontal propagation of leader channel. PBPs in positive CG lightning are classified as +PBP (11 cases) and -PBP (15 cases) according to their initial polarities. +PBP and -PBP have similar distributions of both PBP-RS interval and PBP-RS ratio, but their value of PBP-RS interval is much larger and their value of PBP-RS ratio is much smaller than corresponding values of PBPs in negative CG lightning. It is speculated that different initial polarities of +PBP and -PBP in positive CG lightning are caused by different directions of channel propagation. (C) 2013 Elsevier Ltd. All rights reserved.
  • Eiichi Yoshikawa; Tomoo Ushio; Zen Kawasaki; Satoru Yoshida; Takeshi Morimoto; Fumihiko Mizutani; Masakazu Wada
    IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC 51 (5) 3077 - 3088 0196-2892 2013/05 [Refereed]
     
    A fast-scanning phased array weather radar (PAWR) with a digital beam forming receiver is under development. It is important in beam forming for weather radar observation with temporally high resolution to form a stable and robust main lobe and adaptively suppress sidelobes with a small number of pulses in order to accurately estimate precipitation profiles (reflectivity, mean Doppler velocity, and spectral width). A minimum mean square error (MMSE) formulation with a power constraint, proposed in this paper, gives us adaptively formed beams that satisfy these demands. The MMSE beam-forming method is compared in various precipitation radar signal simulations with traditional beam-forming methods, Fourier and Capon methods, which have been applied in atmospheric research to observe distributed targets such as precipitation, and it is shown that the MMSE method is appropriate to this fast-scanning PAWR concept.
  • Nadir Observations of Lightning and TLEs by JEM-GLIMS
    M. Sato; T. Ushio; T. Morimoto; M. Suzuki; A. Yamazaki; M. Kikuchi; Y. Takahashi; I. Umran; L. Ivan; Y. Hobara
    EGU General Assembly 2013 --  2013/04 [Refereed]
  • Hiroshi Kikuchi; Satoru Yoshida; Takeshi Morimoto; Tomoo Ushio; Zenichiro Kawasaki
    IEICE TRANSACTIONS ON COMMUNICATIONS IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG E96B (3) 880 - 886 0916-8516 2013/03 
    We examine the relationship between 116 VHF sensor events recorded by the VHF sensor on the Maido-1 satellite and lightning strokes detected by the World Wide Lightning Location Network (WWLLN) to show that most of the VHF sensor events were caused by lightning discharges. For each VHF sensor event, the WWLLN events within 1400 km from the subsatellite point and within 1 sec, 30 sec, and 300 sec of the VHF sensor trigger time are analyzed. We find that the coincidence rates in the North and South American continents, and in Southeast/East Asia and the Australian continent are greater than 0.90. Those in the African and European continents, and in the Pacific and Atlantic Oceans are less than 0.61. These high enough coincidence rates indicate that the VHF sensor events were emitted from lightning, although the coincidence rates in the other regions are quite low because of the low detection efficiency of the WWLLN in the regions. We also focus on 6 coincident events measured by both the VHF sensor and the WWLLN. The incidence angles of the EM waves for the VHF sensor are estimated from the group delay characteristics of the recorded EM waveforms. Compared with the WWLLN lightning locations, the two incidence angles are temporally and spatially coincident. These results indicate that a large fraction of the VHF sensor events are emitted by lightning discharges.
  • Ting Wu; Yuji Takayanagi; Tsuyoshi Funaki; Satoru Yoshida; Tomoo Ushio; Zen Ichiro Kawasaki; Takeshi Morimoto; Yoshitaka Nakamura
    IEEJ Transactions on Fundamentals and Materials 133 (9) 451 - 457 0385-4205 2013 [Refereed]
     
    We present the first analysis of a type of special lightning discharge event, called "isolated large bipolar pulse" (ILBP), produced in winter thunderstorm. ILBP produces single bipolar electric field change waveforms with pulse widths mainly in the range of 7 to 19 μs. The initial positive half cycle and the negative cycle of the bipolar pulse are symmetrical with each other to some extent. ILBP is also a very energetic discharge process, producing very large electric field changes even larger than that produced by positive return strokes. Most of ILBPs are found to be isolated with other discharge processes on a time scale of 1 second, but a few ILBPs also seem to be the initiation of other discharge processes. Based on the similarities and differences between ILBP, narrow bipolar pulse (NBP) and negative return stroke (RS) in winter thunderstorm, we discuss the possibility of ILBP as a special version of NBP in winter thunderstorm and as a special type of negative RS. © 2013 The Institute of Electrical Engineers of Japan.
  • Yuji Takayanagi; Manabu Akita; Yoshitaka Nakamura; Satoru Yoshida; Takeshi Morimoto; Tomoo Ushio; Zen Ichiro Kawasaki; Daohong Wang; Nobuyuki Takagi; Hitoshi Sakurano; Yoshiyuki Kubouchi
    IEEJ Transactions on Fundamentals and Materials 133 (3) 132 - 141 0385-4205 2013 
    We have been designing and developing a 3-D lightning location system based on the broadband digital interferometry technique in LF bands. The LF broadband digital interferometer (LF DITF) consists of four or more LF receivers which detect electromagnetic (EM) waves in a wide frequency range from 400 Hz to 1 MHz associated with lightning discharges. Since each receiver detects EM waves in LF, the LF DITF is able to locate lightning discharges in several hundred kilometers. During the winter season in 2010-2011, a simultaneous observation of a LF DITF, a VHF DITF, and Rogowski coils was conducted in Hokuriku, Japan, which borders the Sea of Japan, for evaluation of the LF DITF for locating upward leaders and further understanding of winter lightning in Japan. We show the time series variation of the cases of a bipolar lightning flash and of an upward negative flash. © 2013 The Institute of Electrical Engineers of Japan.
  • Hiroshi Kikuchi; Satoru Yoshida; Takeshi Morimoto; Tomoo Ushio; Zen Ichiro Kawasaki
    IEEJ Transactions on Fundamentals and Materials 133 (4) 159 - 165 0385-4205 2013 
    The well-developed thundercloud causes local downpours and tornadoes accompanied with lightning discharges. The remote sensing for lightning discharges from space is useful for the short-term forecast of weather disasters over vast areas, the understanding of global electrical circuit, and so forth. The broadband digital interferometer (DITF) has been already used to study on the lightning activities as ground-based equipment. The DITF makes it possible to visualize lightning channels by VHF radio observations. The goal of the study, in future, is to realize the space borne DITF and to monitor the thunderstorm activities constantly. In 2012, global lightning and sprite measurements (GLIMS) mission is started its observations on exposed facility of Japanese experiment module (JEM-EF) of the international space station (ISS). The very high frequency (VHF) broadband digital interferometer (VITF) attached on JEM-EF is designed to estimate the direction of arrival with about 10 km resolution. This paper discusses the propagation characteristics through the ionosphere of the VHF radio waves with Lightning Discharges. The numerical simulation based on the ray-tracing method in consideration of the electron density in the ionosphere is performed. The electron density in the nighttime ionosphere has an insignificant effect on the propagation path of the VHF waves, while the electron density in the daytime ionosphere causes the distance error between the radiation source and the estimated radiation source using the VITF is greater than several tens of kilometers when the incident angle for the VITF antenna is greater than 60 degrees. © 2013 The Institute of Electrical Engineers of Japan.
  • AKITA M.; KAWASAKI Z.; YOSHIDA S.; MORIMOTO T.; USHIO T.
    Journal of Atmospheric Electricity Society of Atmospheric Electricity of Japan 32 (2) 55 - 63 0919-2050 2012/07 
    We propose a new method of estimation for the amount of charge removed by individual lightning flashes in thunderclouds by means of three-dimensional (3D) VHF images and the associated electric field (E-field) change on the ground. In this method, we assume a reasonable assumption that the VHF sources located by the VHF broadband digital interferometers (VHF DITFs) correspond to charge transfer of each breakdown. We examine 3D VHF images recorded in Darwin, Australia and estimate the amount of charge removed by lightning discharges in thunderclouds. The average amount of charge removed in a CG and an IC flash is 28 C and 33 C, respectively. These results are in reasonable agreement with previous estimations for the amount of charge transferred using E-field measurements. The charge density removed by an IC flash was also estimated to be 4.3 × 10-10 C/m3 for the positive charge region and 5.8 × 10-9 C/m3 for the negative charge region, respectively. The estimation results indicate the charge structure before the flash occurred in thunderclouds.
  • S. Yoshida; C. J. Biagi; V. A. Rakov; J. D. Hill; M. V. Stapleton; D. M. Jordan; M. A. Uman; T. Morimoto; T. Ushio; Z. -I. Kawasaki; M. Akita
    JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES AMER GEOPHYSICAL UNION 117 (D0911) 2169-897X 2012/05 
    We examine VHF interferometric images, channel-base currents, and broadband electric field waveforms of the initial stage (IS) in two rocket-and-wire triggered lightning flashes. Two types of negative leaders, termed "long-duration" and "short-duration" leaders, were imaged by the VHF interferometers during the IS of the two flashes. There were three leaders that had relatively long durations of more than a few milliseconds. These three leaders were not accompanied by a significant change of channel-base current during their early stages of development, indicating that they corresponded to intracloud (IC) discharges that were not connected to the grounded triggered-lightning channel. Two of these three leaders eventually connected to the triggered-lightning channel and initiated initial continuous current (ICC) pulses. The third long-duration leader apparently developed from the vicinity of an isolated negative charge region toward an upper-level positive charge region and toward a branch of the grounded channel; it served to bridge the positive charge region and the triggered-lightning channel, resulting in the opposite polarity portion of the bipolar ICC. The short-duration negative leaders had durations of some hundreds of microseconds. These negative leaders apparently recoiled along the conductive channels created by branches of the upward positive leader (UPL); they initiated ICC pulses when the grounded channel was sufficiently conductive. It follows that ICC pulses can be initiated either by recoil leaders or via interception of separate in-cloud leaders by a grounded current-carrying channel.
  • Satoru Yoshida; Manabu Akita; Takeshi Morimoto; Tomoo Ushio; Zen Kawasaki
    ATMOSPHERIC RESEARCH ELSEVIER SCIENCE INC 106 86 - 92 0169-8095 2012/03 
    We conducted lightning observation campaign using VHF broadband digital interferometers (DITFs) in Darwin, Australia. We divided a stepped leader into two parts; the first part is a stepped leader propagating almost horizontally in the charge regions (ICR) of thunderclouds and the last part is a stepped leader descending out of the charge region (OCR). The VHF observation indicates that the channels of the stepped leaders OCR located by the DITFs were clearly broader than the channels of the stepped leaders ICR and dart leaders, indicating that the stepped leaders OCR descended in a heavily branched manner. High speed video camera images of a CG flash support the idea that stepped leaders OCR descend in a heavily branched manner. (C) 2011 Elsevier B.V. All rights reserved.
  • Ting Wu; Wansheng Dong; Yijun Zhang; Tsuyoshi Funaki; Satoru Yoshida; Takeshi Morimoto; Tomoo Ushio; ZenIchiro Kawasaki
    JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES AMER GEOPHYSICAL UNION 117 (D0511) 2169-897X 2012/03 
    Discharge heights of thousands of narrow bipolar events (NBEs) observed in Guangzhou and Chongqing of China are calculated using time delays between the direct wave signals of NBEs and their ionospheric reflection pairs. The result shows that most positive NBEs occur between 8 and 16 km while most negative NBEs occur between 16 and 19 km. Very few negative NBEs are above 19 km or below 14 km. It is inferred that positive NBEs are produced between main negative charge layer and upper positive charge layer while negative NBEs are produced between upper positive charge layer and negative screening charge layer at the cloud top. Variations of NBE discharge heights in two thunderstorms are analyzed. It seems that NBEs can be produced at any position between corresponding charge layers. Positive NBEs are generally higher in the periods when negative NBEs are also occurring. For a given short time period in a single thunderstorm, negative NBEs are always observed to occur at a higher altitude than positive NBEs, indicating a dividing charge layer between positive NBEs and negative NBEs. The possibility of some NBEs as upward discharges from cloud tops mentioned by previous studies is discussed. Supported by multiple evidences, we believe such possibility is very low; instead, NBEs are produced in vigorous convective surges that develop to the height comparable to the discharge height of NBEs. Differences in height distributions in Guangzhou and Chongqing are analyzed and a hypothesis is put forward that both positive NBEs and negative NBEs can only be produced above certain height. The relationship between this hypothesis and the mechanism for NBE production is discussed.
  • S. Yoshida; C. J. Biagi; V. A. Rakov; J. D. Hill; M. V. Stapleton; D. M. Jordan; M. A. Uman; T. Morimoto; T. Ushio; Z. I. Kawasaki; M. Akita
    Journal of Geophysical Research Atmospheres 117 (9) 0148-0227 2012 [Refereed]
     
    We examine VHF interferometric images, channel-base currents, and broadband electric field waveforms of the initial stage (IS) in two rocket-and-wire triggered lightning flashes. Two types of negative leaders, termed "long-duration" and "short-duration" leaders, were imaged by the VHF interferometers during the IS of the two flashes. There were three leaders that had relatively long durations of more than a few milliseconds. These three leaders were not accompanied by a significant change of channel-base current during their early stages of development, indicating that they corresponded to intracloud (IC) discharges that were not connected to the grounded triggered-lightning channel. Two of these three leaders eventually connected to the triggered-lightning channel and initiated initial continuous current (ICC) pulses. The third long-duration leader apparently developed from the vicinity of an isolated negative charge region toward an upper-level positive charge region and toward a branch of the grounded channel; it served to bridge the positive charge region and the triggered-lightning channel, resulting in the opposite polarity portion of the bipolar ICC. The short-duration negative leaders had durations of some hundreds of microseconds. These negative leaders apparently recoiled along the conductive channels created by branches of the upward positive leader (UPL); they initiated ICC pulses when the grounded channel was sufficiently conductive. It follows that ICC pulses can be initiated either by recoil leaders or via interception of separate in-cloud leaders by a grounded current-carrying channel. Copyright 2012 by the American Geophysical Union.
  • Ting Wu; Wansheng Dong; Yijun Zhang; Tsuyoshi Funaki; Satoru Yoshida; Takeshi Morimoto; Tomoo Ushio; Zenichiro Kawasaki
    Journal of Geophysical Research Atmospheres 117 (5) 0148-0227 2012 [Refereed]
     
    Discharge heights of thousands of narrow bipolar events (NBEs) observed in Guangzhou and Chongqing of China are calculated using time delays between the direct wave signals of NBEs and their ionospheric reflection pairs. The result shows that most positive NBEs occur between 8 and 16km while most negative NBEs occur between 16 and 19km. Very few negative NBEs are above 19km or below 14km. It is inferred that positive NBEs are produced between main negative charge layer and upper positive charge layer while negative NBEs are produced between upper positive charge layer and negative screening charge layer at the cloud top. Variations of NBE discharge heights in two thunderstorms are analyzed. It seems that NBEs can be produced at any position between corresponding charge layers. Positive NBEs are generally higher in the periods when negative NBEs are also occurring. For a given short time period in a single thunderstorm, negative NBEs are always observed to occur at a higher altitude than positive NBEs, indicating a dividing charge layer between positive NBEs and negative NBEs. The possibility of some NBEs as upward discharges from cloud tops mentioned by previous studies is discussed. Supported by multiple evidences, we believe such possibility is very low; instead, NBEs are produced in vigorous convective surges that develop to the height comparable to the discharge height of NBEs. Differences in height distributions in Guangzhou and Chongqing are analyzed and a hypothesis is put forward that both positive NBEs and negative NBEs can only be produced above certain height. The relationship between this hypothesis and the mechanism for NBE production is discussed. Copyright 2012 by the American Geophysical Union.
  • Yuji Takayanagi; Manabu Akita; Yoshitaka Nakamura; Satoru Yoshida; Takeshi Morimoto; Tomoo Ushio; Zen Kawasaki
    2012 31st International Conference on Lightning Protection, ICLP 2012 2012 [Refereed]
     
    We have been designing and developing a 3D lightning location system based on the broadband digital interferometry technique in VLF/LF band. The VLF/LF broadband digital interferometer (VLF/LF DITF) is able to locate lightning discharges such as return strokes, K events, and compact intracloud lightning discharges (CIDs), which are energetic breakdowns within thunderclouds several hundred kilometers away from the VLF/LF DITF. From July 2011 to now, a simultaneous observation of a VLF/LF band DITF and VHF broadband digital interferometers (VHF band DITF) were conducted in Kansai, Japan. We show the time series variation of an intracloud discharge initiated by a preliminary breakdown pulse train (PB), negative cloud to ground flash and intracloud discharge including K-event. VLF/LF DITF successfully located not only energetic breakdowns within thunderclouds but also leader processes. © 2012 IEEE.
  • Takeshi Morimoto; Hiroshi Kikuchi; Mitsuteru Sato; Makoto Suzuki; Atsushi Yamazaki; Tomoo Ushio
    IEEJ Transactions on Fundamentals and Materials 131 (12) 977 - 982 0385-4205 2011 
    Global Lightning and sprIte MeaSurements (GLIMS) mission is scheduled on Exposed Facility of Japanese Experiment Module (JEM-EF) of the International Space Station (ISS). This paper introduced an electromagnetic (EM) payload of JEM-GLIMS mission, very high frequency (VHF) broadband digital In TerFerometer (VITF). VITF consists of a pair of VHF broadband antennas and electronics to record EM waveforms from lightning discharges. It is designed to estimate the direction-of-arrival with about 10 km resolution that is equivalent to the scale of a thundercloud. It means that VITF is able to monitor thunderclouds with lightning activities globally. Comprehensive observations with the optical payloads of JEM-GLIMS mission for lightning activities and related transient luminous events (TLEs) are expected to give us many scientific impacts to the field. The developments of VITF are based on the heritage of VHF sensor on Maido-1 satellite. © 2011 The Institute of Electrical Engineers of Japan.
  • Tomoo Ushio; Mitsuteru Sato; Takeshi Morimoto; Makoto Suzuki; Hiroshi Kikuchi; Atsushi Yamazaki; Yukihiro Takahashi; Yasuhide Hobara; Umran Inan; Ivan Linscott; Yuji Sakamoto; Ryohei Ishida; Masayuki Kikuchi; Kazuya Yoshida; Zen Ichiro Kawasaki
    IEEJ Transactions on Fundamentals and Materials 131 (12) 971 - 976 0385-4205 2011 
    Global Lightning and sprIte MeasurementS (GLIMS) is a mission on the International Space Station (ISS) to detect and locate optical transient luminous events (TLEs) and associated lightning simultaneously from the non-sun-synchronous orbit. It is scheduled to be launched from Japan in January, 2012 as part of the multi-mission consolidated equipment on the Japanese Exposure Module (JEM). Our mission's goals are (1) to detect and locate lightning and sprites within storm scale resolution over a large region of the Earth's surface along the orbital track of the ISS without any bias, (2) to clarify the mechanism by which sprites are generated, and (3) to identify the conditions under which TLEs occur. To achieve these goals, two CMOS cameras, six Photometers, a VLF receiver and VHF interferometer with two antennas are installed at the bottom of the module to observe the TLEs, as well as causative lightning discharges at nadir direction during day and night time. Though the luminous events' so-called sprites, elves and jets have been investigated by numerous researchers all over the world based mainly on ground observations, some important problems have not been fully understood yet. These include the generation mechanisms of columniform fine structures and horizontal offset of some sprites from the parent lightning discharges. In the JEM-GLIMS mission, observations from our synchronized sensors will shed light on the unsolved problems mentioned above regarding TLEs and causative lightning discharges. In this presentation scientific background, instrumentation, and project summaries are given. © 2011 The Institute of Electrical Engineers of Japan.
  • Eiichi Yoshikawa; Yoshitaka Nakamura; Takeshi Morimoto; Tomoo Ushio; Zen Kawasaki; Tomoaki Mega; Katsuyuki Imai; Takashi Nishida; Toshiya Saito; Norio Sakazume
    IEEE National Radar Conference - Proceedings 1097-5659 2009 [Refereed]
     
    A new high resolution Doppler radar, the Ku-band broad band radar, with scanning capability for meteorological application has been developed. Due to the new system design, the BBR can accurately measure the radar reflectivity factor with the range resolution of 5 m and the time resolution of 1 min per 1 volume scan from the nearest range of 50 m to 15 km for 10 W power using pulse compression. In this paper, the brief description of the BBR and the initial observation results are shown. In the calibration, reflectivity factor of the BBR is fairly good agreement with the Joss-Waldvogel disdrometer. In the volume scanning observation, we succeeded to detect fine 3 dimensional structures of precipitation. ©2009 IEEE.

Books etc

  • 雷の疑問56
    鴨川仁; 吉田智; 森本健志 成山堂書店 2021/08

MISC

Industrial Property Rights

Awards & Honors

  • 2017/01 日本大気電気学会 学術研究賞
     雷嵐観測用VHF帯広帯域干渉計の実用化と宇宙への展開 japan_society 
    受賞者: 森本 健志
  • 2016/05 電気学会 電気学術振興賞 進歩賞
     JEM-GLIMSミッションによる国際宇宙ステーションからの雷放電および高高度発光現象の観測 
    受賞者: 牛尾知雄;佐藤光輝;森本健志;鈴木睦;菊池雅行
  • 2016/05 日本電気協会関西支部 電気関係功績者表彰
     電磁波による宇宙からの雷観測 publisher 
    受賞者: 森本 健志
  • 2013/09 電気学会 優秀論文発表賞
     
    受賞者: 森本 健志
  • 2012/05 電気学会 電気学術振興賞 論文賞
     JPN
  • 2010/05 電気学会 電気学術振興賞 進歩賞
     
    受賞者: 森本 健志
  • 2010 Prize of Progress Award
  • 2008/08 International Union of Radio Science (URSI) Young Scientist Award
     JPN
  • 2008 URSI Young Scientist Award, The XXIX URSI General Assembly
  • 2006/08 電気学会 優秀論文発表賞
     JPN
  • 2004/12 輻射科学研究会 奨励賞
     JPN
  • 2004/07 日本大気電気学会 学生発表表彰
     JPN
  • 2002/08 International Union of Radio Science (URSI） Young Scientist Award
  • 2002 URSI Young Scientist Award

Research Grants & Projects

  • 国際的な科学技術共同研究などの推進 SATREPS
    Date (from‐to) : 2022 -2027 
    Author : 森本 健志
     
    本研究は、中和電荷量が大きく、電力・通信設備や電気・電子機器への落雷被害の脅威となる正極性落雷が多く発生するマレーシア・マラッカ海峡沿岸地域に、雷の前兆となる雲内の微小放電の開始からその進展路を詳細に観測するVHF帯と、広域の雷活動全体を隈なく観測するLF帯を両輪とする電磁界観測網を構築する。放電がどこで始まり、どのように進展し、どこで終わるのかの3D観測データを高速処理して雲内の電荷分布と中和される電荷量を推定し、高構造物とロケット誘雷で直接計測する雷撃電流波形で検証する。電磁界計測および雷撃電流計測によって、雷放電に関わる空中の電荷挙動を網羅的に捉え、その情報に基づく雲内電荷分布推定と発雷予測を実現する。また、IoTやAIを活用した送配電線網や電力機器の制御や極端気象災害の早期警報の社会実装を進めるとともに、誘雷による能動的耐雷・避雷対策について研究する。
  • Study on the lightning initiation problem via observations of high-energy atmospheric phenomena
    Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (A)
    Date (from‐to) : 2022/04 -2026/03 
    Author : 榎戸 輝揚; 中澤 知洋; 一方井 祐子; 森本 健志; 鴨川 仁
  • ガンマ線と電波の同時マッピング観測で挑む雷が起こす光核反応の物理
    日本学術振興会：科学研究費助成事業 基盤研究(A)
    Date (from‐to) : 2019/04 -2022/03 
    Author : 榎戸 輝揚; 鴨川 仁; 森本 健志; 小野 英理
     
    本研究では、世界的にも珍しい日本海沿岸の冬季雷や冬季雷雲に着目し、それらの雷活動に伴う放射線の信号の観測と、理論モデルの構築を電波、可視光、Ｘ線、ガンマ線までの多波長観測データに基づいて行う。もともと別分野として活動してきた、高エネルギー物理学、大気科学、気象学などの分野を融合させ、「高エネルギー大気物理学」という新しい分野の創出を狙うものである。２０１９年度は、放射線測定器の開発を進め、シチズンサイエンスの枠組みを活用できるような可搬型で操作の簡単なモニタリング観測用の放射線測定器（カミナリ百葉箱）の大量生産の目処がたった。また、これまでに蓄積された観測データの解析をすすめ、柏崎刈羽原子力発電所内で観測された地球ガンマ線(Terrestial Gamma-ray Flash)で電子の加速領域の高度やアバランシェ増幅された電子の量の推定を行い論文にまとめた(Wada, Enoto, et al. "Downward Terrestrial Gamma-Ray Flash Observed in a Winter Thunderstorm", Physical Review Letters, Volume 123, Issue 6, id.061103)。また、金沢の２つの高校に設置した観測装置により、雷雲からのガンマ線が雷放電に伴って消失し、光核反応が起きるという現象を観測、解析し、論文にまとめた(Wada, Enoto, et al., "Gamma-ray glow preceding downward terrestrial gamma-ray flash", Communications Physics, Volume 2, Issue 1, id.67)。後者はプレスリリースを行った。電波や電場の測定準備も進めている。
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C)
    Date (from‐to) : 2016/04 -2019/03 
    Author : Yoshitaka Nakamura
     
    To study the relationship between lightning activity and snow cloud mode, we classified snowfall clouds into three types by their shapes and radar echo motions: (1) L-mode clouds that develop parallel to the wind direction, (2) T-mode clouds that develop perpendicular to the wind direction, and (3) V-mode clouds that is strongest spiral convection cloud in the JPCZ. Based on lightning flash rate, L-mode clouds is higher than T-mode clouds in lightning activity. L-mode clouds could be divided into those with and without lightning. Our observations suggest that the JPCZ greatly influences lightning activities in Hokuriku.
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for Young Scientists (B)
    Date (from‐to) : 2014/04 -2018/03 
    Author : MORIMOTO Takeshi
     
    Observations for lightning channels and related electric field changes were continued for in summer and winter thunderstorm seasons throughout the research period. Simultaneous observation of thunderclouds with high resolution weather radar also performed remote sensing of potential thunderstorm energy from comprehensive analysis of various observation results. An estimation method of neutralized electric charge amount considering lighting channels was proposed and applied instead of the way based on a point charge model. Approximate neutralized charge quantity estimation was realized for cloud-to-cloud lightning flashes including the ones with horizontal very long progression. In the thunderclouds which passed through the observation range of the radar, the convective activity became active immediately before the peak of the lightning activity, and declined from high altitude.
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)
    Date (from‐to) : 2012/04 -2016/03 
    Author : SATO Mitsuteru; USHIO Tomoo; MORIMOTO Takeshi; HOBARA Yasuhide; TAKAHASHI Yukihiro; SUZUKI Makoto; TSUCHIYA Fuminori; OYA Hiroyo; KAMOGAWA Masashi; NAKADA Hiroyuki; ADACHI Toru
     
    The main objective of this research is to identify the occurrence conditions of sprites. For this purpose, the horizontal distributions of sprites and the electrical properties of the sprite-producing lightning discharges are studied using the data obtained by the JEM-GLIMS measurements at the ISS and using ground-based lightning data. First, we established the analytical method to identify weak sprite emissions from the incomparably intense lightning emissions in the JEM-GLIMS data. Based on the detailed data analyses of the 42 sprite events identified by that method, the spatial distributions of sprites and the horizontal displacement of the sprites from the sprite-producing lightning discharges are quantitatively identified. From the detailed comparison between the sprite distributions and source locations of the VHF pulses excited by the sprite-producing lightning currents, which is the first result in the world, the occurrence conditions of the sprites are clarified.
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (S)
    Date (from‐to) : 2010/04 -2015/03 
    Author : KAWASAKI Zenichiro; USHIO Tomoo; MORIMOTO Takeshi; YOSHIDA Satoru; NAKAMURA Yoshitaka
     
    We have built a world leading thunderstorm observation network with quite high resolution, including Ku broadband radars, a phased array weather radar, VHF broadband digital interferometers, and Broadband Observation network for Lightning and Thunderstorm (BOLT). We proposed and validated the latest remote sensing technique such as precipitation attenuation correction technique, clutter removal technique, and lightning imaging technique using adaptive signal processing. Thunderstorm observation carried out during summer and winter revealed physics of lightning discharges and relationship between thunderstorm physical process and electrical process.
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)
    Date (from‐to) : 2010/04 -2014/03 
    Author : USHIO Tomoo; YOSHIDA Satoru; MORIMOTO Takeshi; NAKAMURA Yoshitaka; KAWASAKI Zen-ichiro; SATO Mitsuteru; IMAI Katsuyuki
     
    In this research project, two observation system was developed, and successfully operated for thunderstorm electrification process studies. One observation system is an electric field observation system which measures electric field changes at LF band at multipoint, and another system is broad band radar observation network. In the lightning observation system, the time of arrival technique is applied to locate the sources of pulses emitted from lightning process. The height histogram of the initia breakdown process shows the tripole electrical structure of the thunderstorm on the assumption that the negative leader toward the positively charged region and the positive leader toward the negatively charged region produce the impulses at LF band. The relationship with the radar reflectivity factor measured by the broad band radar and phased array radar network was also discussed.
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (A)
    Date (from‐to) : 2007 -2010 
    Author : KAWASAKI Zenichiro; TOMOO Ushio; TAKESHI Morimoto
     
    A high-resolution precipitation and lightning monitoring system was developed and operated. This monitoring is mainly utilized the Ku-band broadband radar (BBR) and the VHF broadband digital interferometer (DITF). The BBR can accurately measure the radar reflectivity factor and the mean Doppler velocity with 5 m resolution over a range from 40 m to several kilometers for 10 W power using a pulse compression technique. Two or more DITFs make us visualize lightning channel propagations in three dimensions. Moreover, we add new functions that integrate these observation data and disclose integration analyses results with the quasi real-time information disclosure system. Initial observations for severe storms with lightning during summer and winter thunderstorm season by these monitoring instruments indicate that we obtain detailed precipitation distribution and detect active convective cells with lightning discharges.
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (A)
    Date (from‐to) : 2006 -2009 
    Author : KAWASAKI Zen-ichiro; USHIO Tomoo; MORIMOTO Takeshi; TAKAGI Nobuyuki; WANG Daohong; NAKAJIMA Teruyuki; HAYASHI Syugo; ARTHUR Jim; MAY Peter; CHRISTIAN Hugh; WILLIAMS Earle; HOELLER Hartmut
     
    We have conducted field campaign in Darwin, Australia to study on giant thunderstorm, Hector by means of our original combined lightning observation network with meteorological equipments operated by Bureau of Meteorology Australia. Lightning leader channels with long horizontal developments are successfully visualized. It is concluded that the horizontal long negative leaders in cloud-to-ground flashes progress along the boundary of positive charge region. When the leaders reach the end of the positive charge regions, they change their direction to downward. An innovative estimation for charge distributions neutralized by lightning flashes is tried out. Ascent of positive charge with Hector developments is noticed.
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for Young Scientists (B)
    Date (from‐to) : 2006 -2008 
    Author : MORIMOTO Takeshi
     
    研究機関の3ヶ年に亘り、毎年11月から1月にかけて、石川県河北郡内灘町を中心とする地域で冬季雷観測を実施した。冬季雷に特徴的な高構造物からの上向き放電で開始する雷放電に着目し、一連の雷放電現象であるにも関わらず、雷雲内の正負両極性の電荷を中和するような放電現象の観測に成功したり、連続電流発生時の電荷移動の推定に成功したりするなどの成果を挙げた。雷放電起源の高エネルギー粒子の発生を観測することによる雷放電への逃走絶縁破壊の影響を確認したことも特筆すべき成果である。
  • 高度製造技術と革新的設計の融合による汎用小型衛星の研究開発
    その他の研究制度
    Date (from‐to) : 2003 -2007
  • IT技術に基づく雷活動実時間監視システムとその情報網・電力網制御への応用
    科学研究費補助金
    Date (from‐to) : 2005 -2006
  • Real-time lightning monitoring system and its applications for power and communications network control
    Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (A)
    Date (from‐to) : 2004 -2006 
    Author : KAWASAKI Zenichiro; USHIO Tomoo; MORIMOTO Takeshi; WANG Daohung; FUNAKI Tsuyoshi; MATSUDA Takahiro
     
    This research is devoted to realize a real-time monitoring system for lightning activities in Kinki district. The principal equipments for the observations are VHF Broadband Digital Interferometer (DITF). DITF is a system to image precise lightning channels and monitor lightning activity widely. The feature of the system is its ultra-wide bandwidth (from 25MHz to 100MHz) and implicit redundancy for estimating VHF source location. Since it is known that VHF impulses are mainly radiated from the tip of breakdown, the locations for their sources are equivalent to imaging the lightning channel development. Moreover recent investigations suggest that locations of negative breakdown source may give us information on positive charge distribution inside thunderclouds as well A single DITF site provides the VHF impulse source mapping in 2D, namely azimuth and elevation. It means that we are able to image lightning channels in 2D without any data communication with other observations sites. This is a one of significant advantages of the system to other techniques for EM radiation source localization. First, we actualize the real-time display of the 2D mapping on this advantage and increases in computing capability. Next, application software for DITF data processing have been developing with new algorithm to improve its accuracy. The development has focused on the removing process for interferometry known as "fringe ambiguity", quickness of data processing, and easily operations. In DITF, waveforms of VHF impulses less than size of on-board memory in 1 s are stored as one dataset. In other words the maximum number of VHF impulses is 2000 in the case of the experimental system and the maximum duration is 1 s for one dataset. It takes less than 1 s to apply the mapping process for one dataset. If we process the data for every data acquisition immediately, the 2D mapping is displayed in at most 1 s on the A data transmitting system of 3D localization data by 3-station-DITF-network through the Internet has been also actualized. 2D data are delivered to data processing center and they are coordinated automatically. The applications for power and communications network control remains an issue.

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