MF研究者総覧

研究者データベース

詳細
宮本　淳(ミヤモト　アツシ)
大学院教育推進機構　教育プログラム推進部
教授
researchmap個人ページ
Last Updated :2023/09/05

基本情報

所属

  • 大学院教育推進機構　教育プログラム推進部

職名

  • 教授

学位

  • 博士（地球環境科学）（北海道大学）

ホームページURL

J-Global ID

研究キーワード

  • 教学IR   高等教育   氷   結晶組織   氷床コア   力学試験   X線ラウエ法   雪   格子定数   フィルン   氷床   転位密度   深さ依存性   南極   ドームふじ   X線回折   

研究分野

  • 人文・社会 / 高等教育学 / 大学院教育
  • 人文・社会 / 教育学
  • 人文・社会 / 科学教育
  • 自然科学一般 / 固体地球科学
  • 環境・農学 / 環境動態解析
  • ナノテク・材料 / 結晶工学
  • ナノテク・材料 / 応用物性

職歴

  • 2023年04月 - 現在 北海道大学 大学院教育推進機構 教授
  • 2022年04月 - 2023年03月 北海道大学 大学院教育推進機構 特任准教授
  • 2020年04月 - 2022年03月 北海道大学 高等教育推進機構 特任准教授
  • 2017年07月 - 2020年03月 北海道大学 総合IR室教学部門 特任准教授
  • 2013年 - 2017年07月 北海道大学 高等教育推進機構 特任准教授
  • 2010年 - 2013年 北海道大学 低温科学研究所 その他

研究活動情報

論文

  • Tomotaka Saruya, Shuji Fujita, Yoshinori Iizuka, Atsushi Miyamoto, Hiroshi Ohno, Akira Hori, Wataru Shigeyama, Motohiro Hirabayashi, Kumiko Goto-Azuma
    The Cryosphere 16 7 2985 - 3003 2022年07月27日 
    Abstract. The crystal orientation fabric (COF) of a polar ice sheethas a significant effect on the rheology of the ice sheet. With the aim ofbetter understanding the deformation regime of ice sheets, the workpresented here investigates the COF in the upper 80 % of the Dome FujiStation ice core in East Antarctica. Dielectric anisotropy (Δε) data were acquired as a novel indicator of the verticalclustering of COF resulting from vertical compressional strain within thedome. The Δε values were found to exhibit a generalincrease with depth, but with fluctuations over distances in the order of10–102 m. In addition, significant decreases in Δεwere found to be associated with depths corresponding to three major glacialto interglacial transitions. These changes in Δε areascribed to variations in the deformational history caused by dislocationmotion occurring from near-surface depths to deeper layers. Fluctuations inΔε over distances of less than 0.5 m exhibited a stronginverse correlation with Δε at depths greater thanapproximately 1200 m, indicating that they were enhanced during theglacial-interglacial transitions. The Δε data alsoexhibited a positive correlation with the concentration of chloride ions andan inverse correlation with the amount of dust particles in the ice core atgreater depths corresponding to decreases in the degree of c axis clustering.Finally, we found that fluctuations in Δε persisted toapproximately 80 % of the total depth of the ice sheet. These data suggestthat the factors determining the deformation of ice include theconcentration of chloride ions and the amount of dust particles, and thatthe layered contrast associated with the COF is preserved all the way fromthe near-surface to a depth corresponding to approximately 80 % of thethickness of the ice sheet. These findings provide important implicationsregarding further development of the COF under the various stress-strainconfigurations that the ice will experience in the deepest region,approximately 20 % of the total depth from the ice/bed interface.
  • Yutaka Kurosaki, Sumito Matoba, Yoshinori Iizuka, Masashi Niwano, Tomonori Tanikawa, Takuto Ando, Akira Hori, Atsushi Miyamoto, Shuji Fujita, Teruo Aoki
    Journal of Geophysical Research: Atmospheres 125 16 2020年08月27日
  • 日本における《カレッジ・インパクト理論》の有効性の検証−日本の一大学のIRデータを使って−
    細川敏幸, 山田邦雅, 宮本淳
    高等教育ジャーナル-高等教育と生涯学習- 27 45 - 54 2020年03月 [査読有り][通常論文]
  • IRデータによる学生層と大学層の形成と評価のシミュレーション
    山田邦雅, 宮本淳, 細川敏幸
    高等教育ジャーナル－高等教育と生涯学習－ 26 67 - 76 2019年03月 [査読無し][通常論文]
  • 学習状況調査アンケートの動向ー米国と韓国の現在ー
    細川敏幸, 山田邦雅, 宮本淳
    高等教育ジャーナル－高等教育と生涯学習－ 26 59 - 65 2019年03月 [査読無し][通常論文]
  • 米国高等教育機関における数学IRの訪問調査
    宮本淳, 山田邦雅, 細川敏幸
    高等教育ジャーナル－高等教育と生涯学習－ 26 77 - 81 2019年03月 [査読無し][通常論文]
  • 宮本 淳, 出口寿久, 伊藤一馬, 川西奈津美, 河野未幸, 鈴木里奈, 高原めぐみ, 中川紗百合, 柳川仁美, 細川敏幸
    高等教育ジャーナル－高等教育と生涯学習－ 25 49 - 54 北海道大学高等教育推進機構 2018年03月 [査読無し][通常論文]
  • 飯塚芳徳, 的場澄人, 藤田秀二, 新堀邦夫, 山崎哲秀, 宮本淳, 堀彰,斉藤健, 古川崚仁, 杉山慎, 青木輝夫
    低温科学 75 45 - 52 低温科学第75巻編集委員会 2017年03月 [査読有り][通常論文]
     
    グリーンランドにおける高涵養量域の圧密氷化過程の特徴の解明や近年の人為起源エアロゾルの変遷の解読を目的として，2015 年5 月にグリーンランド南東ドームにおいて，90.45 m の浅層コア掘削を実施した．掘削地点はタシーラク（アンマサリック）から185 km 北に位置している（SE-Dome；67.18°N，36.37°W，3170 m a.s.l.）．掘削孔の氷温は20 m 深において－20.9℃であった．2015 年8 月にコアが日本に輸送され，低温科学研究所の低温室において密度測定や電気伝導度測定などの初期コア解析が行われた．その結果，SE-Dome コアの氷化深度は83-86 m，涵養量は約1.0 m w.e. yr－1 であった．SE-Dome コアは氷床のドームとしては最も高涵養量の地域の一つである．圧密氷化過程を調べたところ，750 kg m－3 以上の密度域において，SE-Dome コアは通常の涵養量地域の浅層コアよりも変形しやすい特徴を持つことが分かった．In order to understand 1) temporal variations of anthropogenic aerosols from European regions under theIcelandic Low with high time resolution, and 2) the snow densification mechanism at a high accumulation dome inGreenland, we drilled a 90.45 m ice core in a high accumulation area of the southeastern Greenland Ice Sheet. Thedrilling site (SE-Dome; 67.18°N, 36.37°W, 3170 m a.s.l.) is located 185 km north of the town of Tasiilaq in southeasternGreenland. The ice temperature is -20.9℃ at 20 m depth, and the site has an average accumulation rate of 1.0 m w.e.yr-1 in water equivalent. The ice core exhibits distinct firn densification. The close-off density of 830 kg m-3 occursat 83.4-86.8 m depth, which is about 20 m shallower than predicted from an empirical model. In the region where thedensity ρ＞750 kg m-3, the densification appears faster than according to the empirical model.
  • Lee Heewon, Miyamoto Atsushi, Choi Jeung Yun
    Journal of Higher Education and Lifelong Learning 24 24 77 - 95 北海道大学高等教育推進機構 2017年03月 [査読無し][通常論文]
     
    The purpose of this study was to investigate the teaching and learning processes experienced byuniversity students in Korea and Japan, and compare and analyze the higher education systems of the twocountries. For this purpose, surveys were conducted in Seoul National University (SNU) and HokkaidoUniversity (HU) based on questionnaires developed by the Korea Educational Development Institute and theInstitutional Research Consortium of the universities, respectively. Approximately 800 students from eachuniversity participated. Each of the surveys contained questions in six categories known to affect academicachievement: the level of class participation, extracurricular activities, active learning, cooperative learning,interaction with professors and academic competencies. After the surveys were concluded, the commonquestions in the two surveys were identified and the results of these questions were compared and analyzed.We found that students from HU had relatively higher levels of interaction with the faculty members,collaborative learning experiences and study hours, but students in SNU scored relatively higher with regardto their attitude in class, and satisfaction with university support, and also had an overall higher score in termsof the average of the learning outcomes. The results of this study will contribute to the analysis of the statusof studentsʼ learning processes in the universities in South Korea and Japan, and provide insights into areasthat require improvement. They will also help develop concrete measures to improve the quality of highereducation in both countries
  • Kenji Kawamura, Ayako Abe-Ouchi, Hideaki Motoyama, Yutaka Ageta, Shuji Aoki, Nobuhiko Azuma, Yoshiyuki Fujii, Koji Fujita, Shuji Fujita, Kotaro Fukui, Teruo Furukawa, Atsushi Furusaki, Kumiko Goto-Azuma, Ralf Greve, Motohiro Hirabayashi, Takeo Hondoh, Akira Hori, Shinichiro Horikawa, Kazuho Horiuchi, Makoto Igarashi, Yoshinori Iizuka, Takao Kameda, Hiroshi Kanda, Mika Kohno, Takayuki Kuramoto, Yuki Matsushi, Morihiro Miyahara, Takayuki Miyake, Atsushi Miyamoto, Yasuo Nagashima, Yoshiki Nakayama, Takakiyo Nakazawa, Fumio Nakazawa, Fumihiko Nishio, Ichio Obinata, Rumi Ohgaito, Akira Oka, Jun'ichi Okuno, Junichi Okuyama, Ikumi Oyabu, Frederic Parrenin, Frank Pattyn, Fuyuki Saito, Takashi Saito, Takeshi Saito, Toshimitsu Sakurai, Kimikazu Sasa, Hakime Seddik, Yasuyuki Shibata, Kunio Shinbori, Keisuke Suzuki, Toshitaka Suzuki, Akiyoshi Takahashi, Kunio Takahashi, Shuhei Takahashi, Morimasa Takata, Yoichi Tanaka, Ryu Uemura, Genta Watanabe, Okitsugu Watanabe, Tetsuhide Yamasaki, Kotaro Yokoyama, Masakazu Yoshimori, Takayasu Yoshimoto
    SCIENCE ADVANCES 3 2 2017年02月 [査読有り][通常論文]
     
    Climatic variabilities on millennial and longer time scales with a bipolar seesaw pattern have been documented in paleoclimatic records, but their frequencies, relationships with mean climatic state, and mechanisms remain unclear. Understanding the processes and sensitivities that underlie these changes will underpin better understanding of the climate system and projections of its future change. We investigate the long-term characteristics of climatic variability using a new ice-core record from Dome Fuji, East Antarctica, combined with an existing long record from the Dome C ice core. Antarctic warming events over the past 720,000 years are most frequent when the Antarctic temperature is slightly below average on orbital time scales, equivalent to an intermediate climate during glacial periods, whereas interglacial and fully glaciated climates are unfavourable for a millennial-scale bipolar seesaw. Numerical experiments using a fully coupled atmosphere-ocean general circulation model with freshwater hosing in the northern North Atlantic showed that climate becomes most unstable in intermediate glacial conditions associated with large changes in sea ice and the Atlantic Meridional Overturning Circulation. Model sensitivity experiments suggest that the prerequisite for the most frequent climate instabilitywith bipolar seesaw pattern during the late Pleistocene era is associated with reduced atmospheric CO2 concentration via global cooling and sea ice formation in the North Atlantic, in addition to extended Northern Hemisphere ice sheets.
  • A Firn Densification Process in the High Accumulation Dome of Southeastern Greenland
    Yoshinori Iizuka, Atsushi Miyamoto, Akira Hori, Sumito Matoba, Ryoto Furukawa, Takeshi Saito, Shuji Fujita, Motohiro Hirabayashi, Satoru Yamaguchi, Koji Fujita, Nozomu Takeuchi
    Arctic, Antarctic, and Alpine Research 49 13 - 27 2017年01月 [査読有り][通常論文]
  • Hiroshi Ohno, Yoshinori Iizuka, Akira Hori, Atsushi Miyamoto, Motohiro Hirabayashi, Takayuki Miyake, Takayuki Kuramoto, Shuji Fujita, Takahiro Segawa, Ryu Uemura, Toshimitsu Sakurai, Toshitaka Suzuki, Hideaki Motoyama
    JOURNAL OF GEOPHYSICAL RESEARCH-EARTH SURFACE 121 7 1230 - 1250 2016年07月 [査読有り][通常論文]
     
    The deepest ice in inland Antarctica is expected to preserve the oldest ice records and to potentially contain microorganisms. However, little is known about the physicochemical conditions in the deepest part of ice sheets. This study investigates the physicochemical properties of the bottom section (3000-3035m) of the Dome Fuji inland ice core, which is located immediately above unfrozen bedrock. The ubiquitous presence of air hydrates and the water isotope composition of ice comparable to the upper main ice core show that the bottom ice is meteoric. However, ion concentrations exhibit abnormal drops at the greatest depths (approximately below 3033m). In the same depth range, microscopic investigations reveal that considerable relocation of air hydrates and microinclusions (water-soluble impurities) occurs, suggesting that the observed reduction in ion concentration results from the segregation of inclusions to ice grain boundaries and the subsequent discharge of chemicals through liquid-water veins. Principal component analysis of ion data supports the meteoric-ice hypothesis, suggesting that the bottom ice had similar original chemistry through all depths. Statistical analyses of chemical data suggest that the water-soluble impurities attached to hydrates or dust (water-insoluble), the ice-soluble chemical species (such as chlorine), and solid particles are less affected by this chemical displacement phenomenon. It is also noteworthy that in the bottom ice, impurity chemicals, which are limiting nutrients for ice-dwelling microorganisms, are concentrated largely to ice-hydrate interfaces, where oxygen, another vital matter for aerobic microorganisms, is also enriched.
  • 宮本淳, 徳井美智代, 山田邦雅, 細川敏幸
    高等教育ジャーナル─高等教育と生涯学習─ 23 23 79 - 85 北海道大学高等教育推進機構 2016年03月 [査読無し][通常論文]
  • 川村 賢二, 本山 秀明, 東 久美子, 藤田 秀二, 古川 晶雄, 中澤 文男, 青木 周司, 東 信彦, 阿部 彩子, 飯塚 芳徳, 植村 立, 内田 努, 大野 浩, 亀田 貴雄, 鈴木 利孝, 高田 守昌, 平林 幹啓, 藤田 耕史, 福井 幸太郎, 堀 彰, 堀内 一穂, 的場 澄人, 宮本 淳
    雪氷研究大会講演要旨集 2016 194  公益社団法人 日本雪氷学会／日本雪工学会 2016年
  • 徳井美智代, 宮本淳, 山田邦雅, 細川敏幸
    高等教育ジャーナル─高等教育と生涯学習─ 22 22 67 - 73 北海道大学高等教育推進機構 2015年03月 [査読無し][通常論文]
  • 大野 浩, 飯塚 芳徳, 宮本 淳, 川尻 竣三, 平松 雅宏, 八久保 晶弘
    雪氷研究大会講演要旨集 2015 224 - 224 公益社団法人 日本雪氷学会／日本雪工学会 2015年
  • 大野 浩, 岩花 剛, 堀 彰, 宮本 淳, 飯塚 芳徳, 八久保 晶弘, 南 尚嗣, 内田 昌男, ラリー・ ヒンズマン, 曽根 敏雄
    雪氷研究大会講演要旨集 2015 157 - 157 公益社団法人 日本雪氷学会／日本雪工学会 2015年
  • 安藤 厚, 細川 敏幸, 大沼 明, 山畑 倫志, 宮本 淳, 徳井 美智代, 山田 邦雅, 竹山 幸作
    高等教育ジャーナル : 高等教育と生涯学習 20 1 1 - 102 北海道大学高等教育推進機構 = Research Division for Higher Education, Institute for the Advancement of Higher Education, Hokkaido University 2013年06月 
    Five Japanese universities (Doshisha University, Hokkaido University, Osaka Prefecture University, Konan University and Kwansei Gakuin University) worked together in the 2009- 2011 Freshman and Senior Survey for quality assurance and enhancement of college teaching and learning. This activity was supported by a Grant-in-Aid from the Ministry of Education, Culture, Sports, Science and Technology (MEXT). Comparative analysis of the 2011 Freshman and Senior Survey focusing on Hokkaido University showed: 1) that general education was good with rich first-year experiences, 2) the credit cap system and encouragement of self-study were working well, 3) the impact of the comprehensive admissions and new general education program, 4) the benefits of general education at a multidisciplinary university, and 5) that the satisfaction, sense of fulfillment and adaptation to university learning were higher among women. In addition, improvement of the career education program is necessary. The Freshman and Senior Survey will be continued for five more years by eight universities with the support of a new MEXT Grant-in-Aid. Through this activity plan advancement of the Institutional Assessment Network is expected.
  • 連携5 大学「一年生・上級生調査2011 年」の北海道大学を中心とした比較分析（報告）─教学評価IR ネットワーク推進のために─
    安藤厚, 細川敏幸, 大沼明, 山畑倫志, 宮本淳, 徳井美智代, 山田邦雅, 竹山幸作
    高等教育ジャーナル─高等教育と生涯学習─ 22 67 - 73 2013年06月 [査読無し][通常論文]
  • 宮本 淳
    低温科学 71 59 - 68 北海道大学低温科学研究所 = Institute of Low Temperature Science, Hokkaido University 2013年03月 [査読有り][通常論文]
     
    氷結晶の方位, 特に氷床コア試料の結晶ｃ軸方位は, 氷床の変形履歴を反映し, 氷床の力学的性質を決定する主要因子として詳細に調べられてきた. 測定装置は, 多くの時間と労力, 操作に熟練を要するユニバーサル・ステージから発展し, 近年は自動測定装置が用いられている. 2000m を超えるような深層コアの解析には自動化された測定装置が有効に用いられているが, 氷床深部に存在する非常に強い単極大型などの特殊な結晶方位分布の詳細を明らかにするには, 十分な測定精度を有していない. そこで, 筆者らはＸ線を用いた半自動化された結晶方位測定装置を開発し, 高精度測定を実現した. 本稿では, この装置の開発について述べ, 研究への適用例について紹介する.Ice crystal c-axis orientation of ice core samples have been investigated in detail as a major controlling factor of the mechanical properties of ice sheets. The universal stage was a common measurement device for c-axis orientation. The measurement procedure using this d...
  • D. Dahl-Jensen, M. R. Albert, A. Aldahan, N. Azuma, D. Balslev-Clausen, M. Baumgartner, A. M. Berggren, M. Bigler, T. Binder, T. Blunier, J. C. Bourgeois, E. J. Brook, S. L. Buchardt, C. Buizert, E. Capron, J. Chappellaz, J. Chung, H. B. Clausen, I. Cvijanovic, S. M. Davies, P. Ditlevsen, O. Eicher, H. Fischer, D. A. Fisher, L. G. Fleet, G. Gfeller, V. Gkinis, S. Gogineni, K. Goto-Azuma, A. Grinsted, H. Gudlaugsdottir, M. Guillevic, S. B. Hansen, M. Hansson, M. Hirabayashi, S. Hong, S. D. Hur, P. Huybrechts, C. S. Hvidberg, Y. Iizuka, T. Jenk, S. J. Johnsen, T. R. Jones, J. Jouzel, N. B. Karlsson, K. Kawamura, K. Keegan, E. Kettner, S. Kipfstuhl, H. A. Kjær, M. Koutnik, T. Kuramoto, P. Köhler, T. Laepple, A. Landais, P. L. Langen, L. B. Larsen, D. Leuenberger, M. Leuenberger, C. Leuschen, J. Li, V. Lipenkov, P. Martinerie, O. J. Maselli, V. Masson-Delmotte, J. R. McConnell, H. Miller, O. Mini, A. Miyamoto, M. Montagnat-Rentier, R. Mulvaney, R. Muscheler, A. J. Orsi, J. Paden, C. Panton, F. Pattyn, J. R. Petit, K. Pol, T. Popp, G. Possnert, F. Prié, M. Prokopiou, A. Quiquet, S. O. Rasmussen, D. Raynaud, J. Ren, C. Reutenauer, C. Ritz, T. Röckmann, J. L. Rosen, M. Rubino, O. Rybak, D. Samyn, C. J. Sapart, A. Schilt, A. M.Z. Schmidt, J. Schwander, S. Schüpbach, I. Seierstad, J. P. Severinghaus, S. Sheldon, S. B. Simonsen, J. Sjolte, A. M. Solgaard, T. Sowers, P. Sperlich, H. C. Steen-Larsen, K. Steffen, J. P. Steffensen, D. Steinhage, T. F. Stocker, C. Stowasser, A. S. Sturevik, W. T. Sturges, A. Sveinbjörnsdottir, A. Svensson, J. L. Tison, J. Uetake, P. Vallelonga, R. S.W. Van De Wal, G. Van Der Wel, B. H. Vaughn, B. Vinther, E. Waddington, A. Wegner, I. Weikusat, J. W.C. White, F. Wilhelms, M. Winstrup, E. Witrant, E. W. Wolff, C. Xiao, J. Zheng
    Nature 493 7433 489 - 494 2013年01月24日 [査読有り][通常論文]
     
    Efforts to extract a Greenland ice core with a complete record of the Eemian interglacial (130,000 to 115,000 years ago) have until now been unsuccessful. The response of the Greenland ice sheet to the warmer-than-present climate of the Eemian has thus remained unclear. Here we present the new North Greenland Eemian Ice Drilling ('NEEM') ice core and show only a modest ice-sheet response to the strong warming in the early Eemian. We reconstructed the Eemian record from folded ice using globally homogeneous parameters known from dated Greenland and Antarctic ice-core records. On the basis of water stable isotopes, NEEM surface temperatures after the onset of the Eemian (126,000 years ago) peaked at 8 ± 4 degrees Celsius above the mean of the past millennium, followed by a gradual cooling that was probably driven by the decreasing summer insolation. Between 128,000 and 122,000 years ago, the thickness of the northwest Greenland ice sheet decreased by 400 ± 250 metres, reaching surface elevations 122,000 years ago of 130 ± 300 metres lower than the present. Extensive surface melt occurred at the NEEM site during the Eemian, a phenomenon witnessed when melt layers formed again at NEEM during the exceptional heat of July 2012. With additional warming, surface melt might become more common in the future. © 2013 Macmillan Publishers Limited. All rights reserved.
  • Satoshi Takeya, Kazumasa Honda, Yoshito Gotoh, Akio Yoneyama, Kazuhiro Ueda, Atsushi Miyamoto, Takeo Hondoh, Akira Hori, Duo Sun, Ryo Ohmura, Kazuyuki Hyodo, Tohoru Takeda
    Journal of synchrotron radiation 19 Pt 6 1038 - 42 2012年11月 [査読有り][通常論文]
     
    Diffraction-enhanced imaging (DEI) is a phase-contrast X-ray imaging technique suitable for visualizing light-element materials. The method also enables observations of sample-containing regions with large density gradients. In this study a cryogenic imaging technique was developed for DEI-enabled measurements at low temperature from 193 K up to room temperature with a deviation of 1 K. Structure-II air hydrate and structure-I carbon dioxide (CO(2)) hydrate were examined to assess the performance of this cryogenic DEI technique. It was shown that this DEI technique could image gas hydrate coexisting with ice and gas bubbles with a density resolution of about 0.01 g cm(-3) and a wide dynamic density range of about 1.60 g cm(-3). In addition, this method may be a way to make temperature-dependent measurements of physical properties such as density.
  • Satoshi Takeya, Kazumasa Honda, Yoshito Gotoh, Akio Yoneyama, Kazuhiro Ueda, Atsushi Miyamoto, Takeo Hondoh, Akira Hori, Duo Sun, Ryo Ohmura, Kazuyuki Hyodo, Tohoru Takeda
    JOURNAL OF SYNCHROTRON RADIATION 19 1038 - 1042 2012年11月 [査読有り][通常論文]
     
    Diffraction-enhanced imaging (DEI) is a phase-contrast X-ray imaging technique suitable for visualizing light-element materials. The method also enables observations of sample-containing regions with large density gradients. In this study a cryogenic imaging technique was developed for DEI-enabled measurements at low temperature from 193 K up to room temperature with a deviation of 1 K. Structure-II air hydrate and structure-I carbon dioxide (CO2) hydrate were examined to assess the performance of this cryogenic DEI technique. It was shown that this DEI technique could image gas hydrate coexisting with ice and gas bubbles with a density resolution of about 0.01 g cm(-3) and a wide dynamic density range of about 1.60 g cm(-3). In addition, this method may be a way to make temperature-dependent measurements of physical properties such as density.
  • Tsutomu Uchida, Atsushi Miyamoto, Takeo Hondoh
    Summaries of JSSI and JSSE Joint Conference on Snow and Ice Research 2011 165  2011年 [査読有り][通常論文]
  • 竹谷 敏, 後藤 義人, 米山 明男, 上田 和浩, 宮本 淳, 本堂 武夫, 堀 彰, 兵藤 一行, 武田 徹
    雪氷研究大会講演要旨集 2011 0 28 - 28 公益社団法人 日本雪氷学会／日本雪工学会 2011年 [査読有り][通常論文]
  • Ilka Weikusat, Atsushi Miyamoto, Sergio H. Faria, Sepp Kipfstuhl, Nobuhiko Azuma, Takeo Hondoh
    JOURNAL OF GLACIOLOGY 57 201 111 - 120 2011年 [査読有り][通常論文]
     
    Ice in polar ice sheets undergoes deformation during its flow towards the coast. Deformation and recrystallization microstructures such as subgrain boundaries can be observed and recorded using high-resolution light microscopy of sublimation-edged sample surfaces (microstructure mapping). Subgrain boundaries observed by microstructure mapping reveal characteristic shapes and arrangements. As these arrangements are related to the basal plane orientation, full crystallographic orientation measurements are needed for further characterization and interpretation of the subgrain boundary types. X-ray Laue diffraction measurements validate the sensitivity of different boundary types with sublimation used by microstructure mapping for the classification. X-ray Laue diffraction provides misorientation values of all four crystal axes. Line scans across a subgrain boundary pre-located by microstructure mapping can determine the rotation axis and angle. Together with the orientation of the subgrain boundary this yields information on the dislocation types. Tilt and twist boundaries composed of dislocations lying in the basal plane, and tilt boundaries composed of nonbasal dislocations were found. A statistical analysis shows that nonbasal dislocations play a significant role in the formation of all subgrain boundaries.
  • Atsushi Miyamoto, Ilka Weikusat, Takeo Hondoh
    JOURNAL OF GLACIOLOGY 57 201 103 - 110 2011年 [査読有り][通常論文]
     
    Ice crystal orientation fabric data from ice cores contain important information concerning the internal structure and the flow behaviour of ice sheets. When ice cores are recovered from the Antarctic and Greenland ice sheets, crystal orientation measurements are performed immediately to obtain fundamental physical property information. In the past, we have measured the c-axis orientation of ice crystals by a manual optical method using a universal stage. This method is very time-consuming, involving tedious work in a cold laboratory. Recently, automated systems have been developed that enable measurement of c-axis orientation, grain size and other microstructures. However, in order to detect the full crystal orientation of an ice crystal, we also need information on its a-axis orientation. A variety of other crystal orientation measurement methods have previously been discussed, but some shortcomings for ice-core studies cannot be neglected. We have developed a crystal-orientation analysing device using the Laue X-ray diffraction method. As this device can measure the orientations of all crystal axes with high accuracy, it is possible to obtain new microstructure information on natural ice crystals. For the first time, we are able to quantify very low subgrain misorientation angles in polar icecore samples, allowing us to investigate micro-deformation features of individual crystals. Here we discuss the analysis process, which is customized to measure standard ice thin sections, and show preliminary results.
  • Uchida Tsutomu, Miyamoto Atsushi, Shin'yama Atsushi, Hondoh Takeo
    JOURNAL OF GLACIOLOGY 57 206 1017 - 1026 2011年 [査読有り][通常論文]
     
    Air-hydrate crystals store most of the ancient air contained in deep ice sheets. We carried out microscopic observations of air-hydrate crystals below 2000 m depth within the ice core from Dome Fuji, Antarctica, to obtain their number and size distributions. We found that the number density continuously decreased with depth, whereas the average size increased, in contrast to findings from shallower depths. In addition, the characteristic perturbations in both number density and average size distribution with climatic changes almost disappeared, although they are clearly observed in shallow cores. These results indicate that the air-hydrate crystals grow considerably in deeper parts of the ice sheet, and this growth is accompanied by the diffusion of air molecules in the ice. The permeation coefficient of the air molecules in the ice sheet was estimated from the geometric parameters of the air-hydrate distributions. This is the first practical evidence comparable to the previous model estimations. It allows us to evaluate the impacts of the air-molecule migration in the ice sheet on the paleoclimatic information recorded in the deep ice cores.
  • Weikusat Ilka, Kipfstuhl Sepp, Faria Sérgio H., Azuma Nobuhiko, Miyamoto Atsushi
    Journal of Glaciology 55 191 461 - 472 International Glaciological Society 2009年06月 
    Subgrain boundaries revealed as shallow sublimation grooves on ice sample surfaces are a direct and easily observable feature of intracrystalline deformation and recrystallization. Statistical data obtained from the EPICA Dronning Maud Land (EDML) deep ice core drilled in East Antarctica cannot detect a depth region of increased subgrain-boundary formation. Grain-boundary morphologies show a strong influence of internal strain energy on the microstructure at all depths. The data do not support the classical view of a change of dominating recrystallization regimes with depth. Three major types of subgrain boundaries, reflecting high mechanical anisotropy, are specified in combination with crystal-orientation analysis.
  • 宮本 淳, Weikusat Ilka, 本堂 武夫
    雪氷研究大会講演要旨集 2009 22 - 22 公益社団法人 日本雪氷学会／日本雪工学会 2009年
  • Atsushi Miyamoto, Takeo Hondoh
    Summaries of JSSI and JSSE Joint Conference on Snow and Ice Research 2008 80  2008年 [査読有り][通常論文]
  • 宮本 淳, 本堂 武夫
    日本雪氷学会全国大会講演予稿集 2007 173 - 173 公益社団法人 日本雪氷学会 2007年
  • A bipolar comparison of deep ice cores from Antarctica(Dome Fuji) and Greenland(GRIP).
    Shoji, H, Miyamoto, A, Shimohara, K, Watanabe O, Fujii, Y, Kamiyama, K, Motoyama, H, Azuma, K, Igarashi, M, Takata, M, Kohno, M, Nakazawa, T, Aoki, S, Kawamura, K, Narita, H, Kawada, K, Azuma, N, Fujita, S, Clausen, H.B, Johnson, S.J
    Memoris of National Institute of Polar Research S  2007年 [査読有り][通常論文]
  • 宮本 淳, 本堂 武夫, 庄子 仁
    日本雪氷学会全国大会講演予稿集 2006 107 - 107 公益社団法人 日本雪氷学会 2006年
  • Atsushi Miyamoto, Hitoshi Shoji, Akira Hori, Takeo Hondoh, Henrik B. Clausen, Okitsugu Watanabe
    ANNALS OF GLACIOLOGY, VOL 42, 2005 42 47 - 52 2005年 [査読有り][通常論文]
     
    To better understand how ice fabric evolves in polar ice sheets, we use X-ray diffraction to measure ice crystal orientations. X-ray measurement equipment which can measure the orientation of the c axis and a axis of each crystal in a thin section with high measurement accuracy was developed. In this study, we present a-axes orientation distribution of the deep part of the GRIP (Greenland summit) ice core. At some depths, we find an anisotropic distribution of a-axes orientation. Long-term uniaxial compression tests are also carried out on the GRIP ice core to investigate the ice fabric evolution process. The c-axis orientation distribution develops into a stronger single maximum as the strain increases up to about 20% strain. We find that the a axes of each grain also tend to cluster close to nearly a mutual direction. We discuss the development process of ice fabrics, taking into consideration the distribution of the a-axis orientations. It is suggested that these fabrics may be attributed to a local simple shear deformation in the deep part of an ice sheet.
  • Hondoh Takeo, Narita Hideki, Hori Akira, Ikeda-Fukazawa Tomoko, Fujii-Miyamoto Michiko, Ohno Hiroshi, Shiraiwa Takayuki, Mae Shinji, Fujita Shuji, Fukazawa Hiroshi, Fukumura Taku, Shoji Hitoshi, Kameda Takao, Miyamoto Atsushi, Azuma Nobuhiko, Wang Yun, Kawada Kunio, Nishio Fumihiko, Motoyama Hideaki, Watanabe Okitsugu
    Memoirs of National Institute of Polar Research, Special Issue 57 63 - 71 2003年03月 [査読有り][通常論文]
     
    Recent results of physical analyses of the Dome Fuji ice core are summarized with special attention to new methods introduced in the present studies．Microphysical processes which affect the ice core records are reviewed to better understand the paIeoclimatic and paleoenvironmental signals stored.
  • Shoji Hitoshi, Miyamoto Atsushi, Shimohara Kimiko, Watanabe Okitsugu, Fujii Yoshiyuki, Kamiyama Kokichi, Motoyama Hideaki, Goto-Azuma Kumiko, Igarashi Makoto, Takata Morimasa, Kohno Mika, Fujita Shuji, Nakazawa Takakiyo, Aoki Shuji, Kawamura Kenji, Narita Hideki, Kawada Kunio, Azuma Nobuhiko, Saito Takashi, Clausen Henrik B, Johnsen Sigfus J
    Memoirs of National Institute of Polar Research, Special Issue 57 86 - 93 2003年03月 [査読有り][通常論文]
     
    Oxgen isotope ratio and chemistry profiles were compared to find the corresponding interstadials during the Wisconsin Ice Age between the GRIP (Greenland) and Dome Fuji (Antarctica) deep ice core data for the past one hundred and sixty thousand years. Eight interstadials in GRIPδ^<18>O profile were found to correspond to those in Dome Fuji δ^<18>O profile. Eleven interstadials in GRIPδ^<18>O profile were found to correspond to those in Dome Fuji chemistry (calcium, nitrate and sulfate) profile, which is better suited for the purpose of interstadial search than the δ^<18>O profile at Dome Fu...
  • Shimohara Kimiko, Miyamoto Atsushi, Hyakutake Kinji, Shoji Hitoshi, Takata Morimasa, Kipfstuhl Sepp
    Memoirs of National Institute of Polar Research, Special Issue 57 161 - 167 2003年03月 [査読有り][通常論文]
     
    Cloudy band stratigraphy was observed in the GRIP and NGRIP, Greenland ice cores. Gray value profiles obtained from the photographic recording were analyzed to extract annual layer signals. Simple counting of gray value peaks is effective enough when annual layer thickness is relatively small (smaller than approximately 20 mm), but smoothing of the gray value profile is needed when annual layer thickness is larger. Smoothing can be done by adopting a running mean over a range of half of annual layer thickness estimated from ice flow modeling. A comparison of the DEP profile with the gray va...
  • Miyamoto Atsushi, Shimohara Kimiko, Hyakutake Kinji, Shoji Hitoshi, Narita Hideki, Hondoh Takeo
    Memoirs of National Institute of Polar Research, Special Issue 57 168 - 177 2003年03月 [査読有り][通常論文]
     
    Mechanical anisotropy of ice core samples has been observed in various uniaxial compression tests. The c-axis orientation distribution is the primary influence on the mechanical behavior of ice cores. A strong single-maximum fabric pattern is observed in the deep parts of the ice sheet. In this region, polycrystalline ice is very hard along the vertical axis; however, it easily shears along the horizontal plane. Thus, by acquiring the distribution of c-axis orientations throughout the ice sheet, the mechanical anisotropy of ice sheet flow behavior can be understood. Analysis of fabric measu...
  • Miyamoto Atsushi, Shoji Hitoshi, Hyakutake Kinji
    Memoirs of National Institute of Polar Research, Special Issue 56 287 - 294 2002年03月 [査読有り][通常論文]
     
    Many tiny cracks are observed near the surface of deep ice cores drilled from polar ice sheets. These cracks probably form during the ice core drilling process at hydrostatic pressure, which increases linearly with depth. We studied crack formation in ice experimentally by deforming ice single crystals using a uniaxial compression apparatus with controlled hydrostatic pressure. The uniaxial compressive stress was applied to ice samples under a hydrostatic pressure of 20 Mpa at -18℃. A constant strain rate was set at 〜10^<-7>s^<-1>. The c-axis orientations of the ice single crystals were par...
  • Hyakutake Kinji, Moribe Atsushi, Miyamoto Atsushi, Shimohara Kimiko, Shoji Hitoshi
    Memoirs of National Institute of Polar Research, Special Issue 56 295 - 301 国立極地研究所 2002年03月 [査読有り][通常論文]
     
    Surface hollows appearing after microtome shaving were observed on poly-and single crystal specimens under an optical microscope in a cold room laboratory. Characteristic shell-shaped hollows appeared with their major axis perpendicular to the shaving direction. Fewer hollows appeared at specimen surfaces when the basal plane of the ice crystal was parallel or perpendicular to the specimen surface. The results observed could be easily interpreted if cleavage cracks form parallel or perpendicular to the basal plane near the blade edge during the microtome shaving process.

その他活動・業績

  • アセスメント・ポリシーの考え方—アセスメント・ポリシー研究会報告—
    細川敏幸, 山田邦雅, 宮本淳 高等教育ジャーナル-高等教育と生涯学習- 25 69 -73 2018年03月 [査読無し][通常論文]
  • 川村賢二, 川村賢二, 川村賢二, 本山秀明, 本山秀明, 東久美子, 東久美子, 藤田秀二, 藤田秀二, 古川晶雄, 古川晶雄, 中澤文男, 中澤文男, 青木周司, 東信彦, 阿部彩子, 阿部彩子, 飯塚芳徳, 植村立, 内田努, 大野浩, 亀田貴雄, 鈴木利孝, 高田守昌, 平林幹啓, 藤田耕史, 福井幸太郎, 堀彰, 堀内一穂, 的場澄人, 宮本淳 雪氷研究大会講演要旨集(Web) 2016 2016年
  • 飯塚 芳徳, 的場 澄人, 大藪 幾美, 山崎 哲秀, 門田 萌, 新堀 邦夫, 青木 輝夫, 斉藤 健, 宮本 淳, 古川 崚仁, 藤田 秀二, 堀 彰, 山口 悟, 大野 浩, 鈴木 利孝, 植村 立, 関 宰, 本山 秀明 雪氷研究大会講演要旨集 2015 190 2015年
  • 飯塚芳徳, 的場澄人, 大藪幾美, 山崎哲秀, 門田萌, 新堀邦夫, 青木輝夫, 斉藤健, 宮本淳, 古川崚仁, 藤田秀二, 堀彰, 山口悟, 大野浩, 鈴木利孝, 植村立, 関宰, 本山秀明 雪氷研究大会講演要旨集(Web) 2015 190(J‐STAGE) 2015年 [査読無し][通常論文]
  • 東久美子, 青木周司, 東信彦, 飯塚芳徳, 植竹淳, 川村賢二, 神田啓史, 倉元隆之, 小端拓郎, 笹公和, 佐藤基之, 瀬川高弘, 高村近子, 中澤高清, 平林幹啓, 藤井理行, 藤田秀二, 堀彰, 堀内一穂, 三宅隆之, 宮本淳, 本山秀明 雪氷研究大会講演要旨集 2010 2010年
  • Kumiko Goto-Azuma, Jun Uetake, Kenji Kawamura, Hiroshi Kanda, Takayuki Kuramoto, Takuro Kobashi, Takahiro Segawa, Chiikako Takamura, Motohiro Hirabayashi, Yoshiyuki Fujii, Shuji Fujita, Takayuki Miyake, Hideaki Motoyama, Shuji Aoki, Takakiyo Nakazawa, Nobuhiko Azuma, Motoyuki Sato, Yoshinori Iizuka, Atsushi Miyamoto, Kimikazu Sasa, Akira Hori, Kazuho Horiuchi Summaries of JSSI and JSSE Joint Conference on Snow and Ice Research 2010 4 2010年01月01日 [査読無し][通常論文]
  • T. Sakurai, A. Miyamoto, Y. Iizuka, T. Hondoh, T. Uchida, S. Fujita Summaries of JSSI and JSSE Joint Conference on Snow and Ice Research 2010 109 -109 2010年01月01日 [査読無し][通常論文]
  • 東 久美子, 東 信彦, 大野 浩, 香内 晃, 河野 美香, 藤田 秀二, 堀川 信一郎, 本堂 武夫, 宮本 淳 雪氷 : 日本雪氷協會雜誌 67 (4) 366 -371 2005年07月15日 [査読無し][通常論文]
  • 第7回国際南極雪氷シンポジウム報告
    堀彰, 藤井理行, 河村俊行, 前野英生, 宮本淳, 飯塚芳徳 雪氷 66巻1号、69-72 2004年 [査読無し][通常論文]
  • 宮本 淳 雪氷 : 日本雪氷協會雜誌 65 (6) 551 -552 2003年11月15日 [査読無し][通常論文]
  • 高田 守昌, 飯塚 芳徳, 庄子 仁, 宮本 淳, Kipfstuhl Sepp, 本堂 武夫, 藤田 秀二, 藤井 理行 南極資料 47 (3) 328 -337 2003年11月 [査読無し][通常論文]
     
    第二期ドームふじ氷床コアプロジェクトの現場解析において,簡便に光学層位を記録するため,専用装置を開発した.この装置は,二次元的な光の散乱強度を氷床コアサンプルの深さ方向に沿って連続的に測定する.我々は,この装置のハードウェアおよび制御ソフトウェアを開発した.この結果,経験のないオペレーターでも容易に測定可能な,自動測定装置が完成した.測定速度は5mm/sを想定しており,この場合,現場処理解析の基本長である1.5mのサンプルを約6分間で測定可能である.この装置は第44次越冬隊が南極ドームふじ観測拠点に搬入し,第45次夏隊から始まる深層コア掘削の現場解析処理に使用される予定である.
  • 藤田 秀二, 東 久美子, 飯塚 芳徳, 堀 彰, 宮本 淳 雪氷 61 (1) 51 -54 1999年01月15日 [査読無し][通常論文]
  • 白井 孝行, 宮本 淳, 本井 達夫, 牛尾 収輝, 藤井 理行, 小西 啓之 雪氷 60 (1) 59 -63 1998年01月15日 [査読無し][通常論文]
  • SHOJI Hitoshi, NARITA Hideki, MIYAMOTO Atsushi, WATANABE Okitsugu, CLAUSEN Henrik B., KIPFSTUHL Josef Proceedings of the NIPR Symposium on Polar Meteorology and Glaciology 11 249 -249 1997年11月 
    Mechanical property studies have been conducted on deep ice core samples to understand the flow dynamics of large polar ice sheets. Uniaxial compression tests were done both on the Dye 3 and GRIP ice core samples from Greenland. The stress axis is inclined 45 degree from core axis in order to have information on horizontal shear deformation behavior of an ice sheet. The results were analyzed by using an enhancement factor, E. C-axis orientation fabric is a dominant factor for E values and can be estimated from vertical compression strain (N. AZUMA and A. HIGASHI, 1985) if preferred orientation is developed by crystal rotation process without recrystalization. E values from Dye 3 and GRIP samples were plotted with normalized depth (=depth/ice thickness), which is a measure of vertical compression strain. Down to a depth around 60% of ice thickness, the E value stays constant around l, and increases below that depth as expected from the single maximum fabric in deeper places. Below a depth around 70% of ice thickness, E exceeds about 10 and E of GRIP ice samples is higher than that of Dye 3 samples in general. This difference could be attributed to chemical impurity contents and/or ice stratigraphic features such as cloudy bands.
  • SHOJI Hitoshi, MIYAMOTO Atsushi, NARITA Hideki Proceedings of the NIPR Symposium on Polar Meteorology and Glaciology 11 246 -246 1997年11月 
    Flow behavior of large ice sheets is affected mainly by c-axis orientation fabric, and the fabric formation is caused by the anisotropic characteristics in the plastic deformation property of ice crystal. There are three processes involved in fabric formation; i.e. crystal rotation (AZUMA and HIGASHI, 1985), recrystalization and polygonization. Two types of crystal fabric development with depth have been observed in deep polar ice cores. Type A shows crystal fabric changes from a random distribution near the surface to vertical cluster development with depth under vertical compression and to a strong single maximum pattern near the bottom under simple shear deformation (Camp Century, Dye 3,GRIP and Byrd ice cores). Type B shows fabric changes from a random distribution near the surface to a large girdle development with depth, where the c-axis direction is almost perpendicular to the uniaxial tensile strain axis along the ice flow direction (Mizuho and Vostok ice cores). To estimate vertical compressive strain, ε and uniaxial tensile strain, γ, the following equations were assumed : ε=-ln(y/H), γ=-2ln(y/H), where y is height from the bottom and H is ice thickness. For Type A cores, the c-axis lies mainly along the vertical core direction with depth and a single maximum fabric appears at depth for about ε=150%, except for Byrd core samples which shows single maximum fabric appearance for about ε=80%. For Type B cores, crystal fabrics developments with an increase in γ are quite similar to each other.
  • Watanabe Okitsugu, Shimada Wataru, Narita Hideki, Miyamoto Atsushi, Tayuki Kazushige, Hondoh Takeo, Kawamura Toshiyuki, Fujita Shuji, Shoji Hitoshi, Enomoto Hiroyuki, Kameda Takao, Kawada Kunio, Yokoyama Kotaro, 庄子 仁, 榎本 浩之, 亀田 貴雄 Proceedings of the NIPR Symposium on Polar Meteorology and Glaciology 11 1 -8 1997年11月 [査読無し][通常論文]
     
    To make a pilot-hole for deep core drilling at Dome Fuji Station, East Queen Maud Land, Antarctica, shallow ice core drilling was conducted to a depth of 112.59 m by electro-mechanical drill. Core logging, measurements of impermeability and bulk density were conducted in situ and most of another analysis was done in Japan．Much depth hoar developed at Dome Fuji Station. However, it did not influence the densification rate, which mainly depends on temperature. Air bubble close-off starts from about 90 m depth. Much accumulation at one time occurs during marine cyclones at Dome Fuji Station.
  • MIYAMOTO Atsushi, SHOJI Hitoshi, NARITA Hideki, WATANABE Okitsugu, CLAUSEN Henrik B, HONDOH Takeo Proceedings of the NIPR Symposium on Polar Meteorology and Glaciology 11 87 -93 1997年11月 [査読無し][通常論文]
     
    We conducted detailed mechanical property investigations of deep polar ice core samples. In order to understand the effect of cloudy band structure on deformation of ice core samples, uniaxial compression tests were carried out by using the GRIP ice core containing cloudy bands. The uniaxial compression tests were performed under the conditions of constant strain rate (Type A) and constant load (Type B) at -15℃. The enhancement factor (Es) correlates with the schmid factor (F) that indicates c-axis orientation development with F less than 0.46. The Es of ice specimens with F larger than 0.4...
  • MIYAMOTO Atsushi, HONDOH Takeo, SHOJI Hitoshi Proceedings of the NIPR Symposium on Polar Meteorology and Glaciology 10 152 -152 1996年09月 
    Ice cores contain important information on climatic conditions in the past. All data sets should be interpreted and discussed on the basis of a reliable core chronology. The uncertainly of ice core dating by a flow model increases for deeper parts of ice sheets. Nevertheless, in this pilot study we estimated a relation between depth and age at Dome Fuji Station, Antarctica, using the Dansgaard-Johnsen model (W. DANSGAARD and S. J. JOHNSEN : J. Glaciol., 8,215,1969) with past accumulation rate changes taken into consideration. The ice flow velocity profiles can be approximated and characterized with one parameter, h, the distance from the bedrock. The vertical strain rate is assumed to be constant from the surface down to the level h=h^* and, further, decreasing linearly to zero at the bedrock. A value of 1200m was adopted for h^* at Dome Fuji Station, which is the value used for the GRIP ice core analysis. Dome Fuji Station, Antarctica, and GRIP site, Greenland, are both located at the summit positions of the ice sheets and the ice thickness values are nearly equal to each other (about 3000m). Depth-age calculations were also performed for h^*=0 to study the influence of parameter h^*. Depths for the Holocene/Wisconsin boundary were obtained as 376 and 370m, respectively. This suggests that the Holocene/Wisconsin boundary is not so sensitive to the ice flow pattern at Dome Fuji Station. Depths for the Wisconsin/Sangamon boundary were also calculated at the assumption that the accumulation rates during the Wisconsin age period was 1/2 (case 1) and 2/3 (case 2) of its presentday values. The resultant estimates were about 1450m (case 1) and 1670m (case 2), respectively. This confirms that the accumulation rate during a glacial period is a major factor which determines a depth-age relation at deeper levels in large ice sheets in ice flow modeling.

受賞

  • 2017年01月 北海道大学 北海道大学平成28年度研究総長賞奨励賞
     
    受賞者: 宮本 淳
  • 2016年02月 北海道大学 北海道大学平成27年度研究総長賞奨励賞
     
    受賞者: 宮本 淳

共同研究・競争的資金等の研究課題

  • 文部科学省：科学研究費補助金(基盤研究(C), 基盤研究(C))
    研究期間 : 2010年 -2012年 
    代表者 : 宮本 淳
     
    本研究は、氷床深部のコア試料や人工単結晶氷試料を用いた実験的研究から氷体の結晶組織、力学的性質等を明らかにし、氷床の内部構造・物性の詳細を知ることを目的に推進している。本年度は標準試料となる単結晶氷試料の作成と力学試験、さらに北グリーンランド氷床深層掘削計画により得られたNEEMコアの結晶組織解析を中心に研究を進めた。単結晶氷試料の作成については、昨年度低温科学研究所技術部と共同で製作した育成装置の改良と実験条件の見直しを行った。新たに種氷を用いることにより、結晶方位を制御した試料の育成に成功し、力学試験に使用可能な試料を継続的に作成することが可能になった。また、この単結晶氷試料を使った力学試験を-15℃の温度条件下で行った。c軸が圧縮軸から45度傾くように一軸圧縮試験を行い、単結晶氷の基底面に最大分解せん断応力が働くように条件を設定した。その結果、変形量の大きいせん断変形部に粒径数mmの再結晶粒が発生した。それぞれの結晶軸方位を調べた結果c軸、a軸ともに揃った方位関係であることが明らかになった。この再結晶粒の方位は母結晶である元の単結晶氷の方位には一致せず、c軸はせん断面にほぼ鉛直で、ひとつのa軸が滑り方向にほぼ一致することもわかった。これは氷床深部のコアにおいて発見されているa軸方位分布を実験的に再現できたことを意味している。つまり、この特殊な結晶方位分布は、当初予想した...
  • 特別研究員奨励費
    研究期間 : 2000年 -2002年 
    代表者 : 宮本 淳

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