Study on physics and layers of ice cores containing information of climate change over the past 720 k-years, and study on the "oldest ice"

2021 Fiscal Year Annual Research Report

• Project/Area Number: 18H05294
• Research Institution: National Institute of Polar Research
• Principal Investigator: 藤田 秀二 国立極地研究所, 研究教育系, 教授 (30250476)
• Co-Investigator(Kenkyū-buntansha): 平林 幹啓 国立極地研究所, 研究教育系, 特任助手 (20399356) ; 飯塚 芳徳 北海道大学, 低温科学研究所, 准教授 (40370043) ; 大野 浩 北見工業大学, 工学部, 准教授 (80634625)
• Project Period (FY): 2018-06-11 – 2023-03-31
• Keywords: 南極 / アイスコア / 気候変動 / 古気候 / 氷床

Outline of Annual Research Achievements

当初計画に従い、以下の項目の研究を遂行した。前年度の計画項目の継続となった。
Ⅰ．アイスコアの物理層位の計測：①ミリ波誘電率テンソルの計測を2400m深から深い側に延伸する計測を前年度の続きとして続行した。② ①とあわせ、結晶Ｃ軸方位の直接計測とを実施し比較を実施した。③ミリ波誘電テンソルにかかる研究成果の論文化したⅡ．連続融解計測装置系（CFA）を用いたアイスコアの化学層位計測：①2020年度までに開発した小型融解ヘッドと中型融解ヘッドの試験を実施した。解析待ちサンプルで、優先度を決めて、CFA解析をすすめ、ナトリウム、カルシウム、ケイ素の濃度について連続高時間分解能の解析を実施した。Ⅲ. 塩微粒子の層位にかかる研究：不純物の存在状態の検知計測を、ラマン分光散乱を用いて継続した。Ⅳ. アイスコアの信号形成にかかるプロセスにかかる研究：前年度には、氷床に閉じ込められてから数百年程度以内の深度約100-120m深の気泡をラマン分光散乱で解析し、気泡中の酸素と窒素の分別比を実測し、初報論文を出版した。それに続き2021年度はさらに事例を増やした。Ⅴ. ドームふじアイスコアの固体電気伝導度解析：DEPデータの解析データを用いて、過去5000年間の氷床表面の質量収支を解明した論文を出版した。Ⅵ. 氷床探査用レーダの観測データとアイスコアデータとの比較：2018年度までに取得した高性能のレーダの解析を継続し、氷床の大深部に存在するアイスコアの層構造との対比を実施した。初報論文として氷床の詳細な基盤地形についての新知見をまとめた論文を出版した。さらには現地の氷床動力学モデルの研究を構築し出版に至った。Ⅶ.アイスコア間の気候変動イベントの年代差の抽出作業に関しては、DFアイスコアの高分解能連続コア解析に対応する欧州側（ドームCコア）のデータが揃っていない状況から、比較作業が進捗していない。

Current Status of Research Progress

2: Research has progressed on the whole more than it was originally planned.

Reason

以下の７項目を総合的にみたとき、順調に論文化まで進捗した項目と、順調とは言えない１項目（Ⅶ）がある。
Ⅰ．アイスコアの物理層位の計測：ミリ波誘電テンソルにかかるデータを氷床全層にわたって揃えることを実現し、まず氷床の８割分の深度に相当する2,400m分の論文出版とデータ出版を実現した。氷床の物理層構造の全層にわたる理解に向けて進捗している。さらにデータは継続して取得しており、全層分の論文出版とデータ出版の準備に至っている。Ⅱ．連続融解計測装置系（CFA）を用いたアイスコアの化学層位計測を、新型ヘッドを用いて確実に進捗されており、ナトリウム、カルシウム、ケイ素の濃度について連続高時間分解能の解析を実施しデータを蓄積しており、計画に沿った研究を実行している。最終年度、本課題に向けての出版作業をすすめる。Ⅲ. 塩微粒子の層位にかかる研究：不純物の存在状態の検知計測を継続しデータ取得を実現している。Ⅳ. アイスコアの信号形成にかかるプロセスにかかる研究：氷床に閉じ込められてから数百年程度以内の深度約100-120m深の気泡をラマン分光散乱で解析し、気泡中の酸素と窒素の分別比を実測し論文を出版したほか、さらに事例を増やしている。Ⅴ. ドームふじアイスコアの固体電気伝導度解析結果を他のアイスコアと年代同期し、そのデータを用いて、過去5000年間の氷床表面の質量収支を解明した応用論文の出版を実現した。Ⅵ. 氷床探査用レーダの観測データとアイスコアデータとの比較を活用し、初報論文として氷床の詳細な基盤地形についての新知見をまとめた論文を出版した。さらには現地の氷床動力学モデルの研究を構築し出版に至った。Ⅶ.アイスコア間の気候変動イベントの年代差の抽出作業に関しては、DFアイスコアの高分解能連続コア解析に対応する欧州側（ドームCコア）のデータが揃っていない状況から、比較作業が進捗していない。

Strategy for Future Research Activity

今後以下の対応をすすめる。
Ⅰ．アイスコアの物理層位の計測：ミリ波誘電テンソル計測にかかるデータを氷床全層にわたって揃え論文出版とデータ出版を実現する。Ⅱ．連続融解計測装置系（CFA）を用いたアイスコアの化学層位計測：最終年度、本課題に向けての論文とデータ双方の出版作業をすすめる。Ⅲ. 塩微粒子の層位にかかる研究：不純物の存在状態の検知計測を継続し連続融解計測装置系（CFA）との比較を実施する。Ⅳ. アイスコアの信号形成にかかるプロセスにかかる研究：データ取得作業をさらなる論文に反映させる。Ⅴ. ドームふじアイスコアの固体電気伝導度解析結果を他のアイスコアと年代同期：連続融解計測装置系（CFA）とあわせ、比較作業の高度化をはかる。Ⅵ. 氷床探査用レーダの観測データとアイスコアデータとの比較：ミリ波誘電テンソル計測にかかるデータとレーダデータの比較を全層で実施する。Ⅶ.アイスコア間の気候変動イベントの年代差の抽出作業：DFアイスコアの高分解能連続コア解析に対応する欧州側（ドームCコア）のデータが揃っていない状況に変化がありうるか確認する。

Research Products

• [Journal Article] Temporal variations of surface mass balance over the last 5000 years around Dome Fuji, Dronning Maud Land, East Antarctica (2023)
  • Author(s): Ikumi Oyabu, Kenji Kawamura, Shuji Fujita, Ryo Inoue, Hideaki Motoyama, Kotaro Fukui, Motohiro Hirabayashi, Yu Hoshina, Naoyuki Kurita, Fumio Nakazawa, Hiroshi Ohno, Konosuke Sugiura, Toshitaka Suzuki, Shun Tsutaki, Ayako Abe-Ouchi, Masashi Niwano, Frederic Parrenin, Fuyuki Saito, Masakazu Yoshimori
  • Journal Title: Climate of the Past Volume: 19(2) Pages: 293-321
  • DOI: 10.5194/cp-19-293-2023
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Accumulation rate, volcanic tie points, ECM, DEP, nssSO4, density and chronology from shallow ice cores around Dome Fuji, East Antarctica (2023)
  • Author(s): Oyabu Ikumi, Kawamura Kenji, Fujita Shuji, Inoue Ryo, Fukui Kotaro, Hirabayashi Motohiro, Hoshina Yu, Kurita Naoyuki, Nakazawa Fumio, Ohno Hiroshi, Sugiura Konosuke, Suzuki Toshitaka, Tsutaki Shun, Abe-Ouchi Ayako, Niwano Masashi, Parrenin Frederic, Saito Fuyuki, Yoshimori Masakazu
  • Journal Title: Arctic Data archive System (ADS), Japan Volume: ^ Pages: -
  • DOI: 10.17592/001.2022081901
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Antarctic Bedmap data: FAIR sharing of 60 years of ice bed, surface and thickness data (2022)
  • Author(s): Alice C Framand and others
  • Journal Title: Earth System Science Data Discussions Volume: - Pages: 1-25
  • DOI: 10.5194/essd-2022-355
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] A one-dimensional temperature and age modeling study for selecting the drill site of the oldest ice core around Dome Fuji, Antarctica (2022)
  • Author(s): Takashi Obase, Ayako Abe-Ouchi, Fuyuki Saito, Suji Fujita, Kenji Kawamura, Hideaki Motoyamahun Tsutaki, Sh
  • Journal Title: The Cryosphere Discussions Volume: - Pages: 1-24
  • DOI: 10.5194/tc-2022-204
  • Peer Reviewed / Open Access
• [Journal Article] High-resolution subglacial topography around Dome Fuji, Antarctica, based on ground-based radar surveys over 30 years (2022)
  • Author(s): Shun Tsutaki, Shuji Fujita, Kenji Kawamura, Ayako Abe-Ouchi, Kotaro Fukui, Hideaki Motoyama, Yu Hoshina, Fumio Nakazawa, Takashi Obase, Hiroshi Ohno, Ikumi Oyabu, Fuyuki Saito, Konosuke Sugiura, Toshitaka Suzuki
  • Journal Title: The Cryosphere Volume: 16(7) Pages: 2967-2983
  • DOI: 10.5194/tc-16-2967-2022
  • Peer Reviewed / Open Access
• [Journal Article] Development of crystal orientation fabric in the Dome Fuji ice core in East Antarctica: implications for the deformation regime in ice sheets (2022)
  • Author(s): Tomotaka Saruya, Shuji Fujita, Yoshinori Iizuka, Atsushi Miyamoto, Hiroshi Ohno, Akira Hori, Wataru Shigeyama, Motohiro Hirabayashi, Kumiko Goto-Azuma
  • Journal Title: The Cryosphere Volume: 16(7) Pages: 2985-3003
  • DOI: 10.5194/tc-16-2985-2022
  • Peer Reviewed / Open Access
• [Journal Article] Dielectric anisotropy as indicator of crystal orientation fabric in Dome Fuji ice core: method and initial results (2022)
  • Author(s): Tomotaka Saruya, Shuji Fujita, Ryo Inoue
  • Journal Title: Journal of Glaciology Volume: 68(267) Pages: 65-76
  • DOI: 10.1017/jog.2021.73
  • Peer Reviewed / Open Access
• [Journal Article] Dome Fuji, Antarctica Core DF2 Dielectric Anisotropy Measurements (2022)
  • Author(s): Saruya Tomotaka, Fujita Shuji
  • Journal Title: Arctic Data archive System (ADS), Japan Volume: - Pages: -
  • DOI: 10.17592/001.2022062101
  • Peer Reviewed / Open Access
• [Journal Article] Surface Mass Balance Controlled by Local Surface Slope in Inland Antarctica: Implications for Ice sheet Mass Balance and Oldest Ice Delineation in Dome Fuji (2021)
  • Author(s): Brice Van Liefferinge, Drew Taylor, Shun Tsutaki, Shuji Fujita, Prasad Gogineni, Kenji Kawamura, Kenichi Matsuoka, Geir Moholdt, Ikumi Oyabu, Ayako Abe‐Ouchi, Abhishek Awasthi, Christo Buizert, Jean‐Charles Gallet, Elisabeth Isaksson, Hideaki Motoyama, Fumio Nakazawa, Hiroshi Ohno and others
  • Journal Title: Geophysical Research Letters Volume: 48(24) Pages: e2021GL094966
  • DOI: 10.1029/2021gl094966
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Fractionation of O2/N2 and Ar/N2 in the Antarctic ice sheet during bubble formation and bubble-clathrate hydrate transition from precise gas measurements of the Dome Fuji ice core (2021)
  • Author(s): Ikumi Oyabu, Kenji Kawamura, Tsutomu Uchida, Shuji Fujita, Kyotaro Kitamura, Motohiro Hirabayashi, Shuji Aoki, Shinji Morimoto, Takakiyo Nakazawa, Jeffrey P Severinghaus, Jacob D Morgan
  • Journal Title: The Cryosphere Volume: 15(12) Pages: 5529-5555
  • DOI: 10.5194/tc-15-5529-2021
  • Peer Reviewed / Open Access
• [Journal Article] Surface heights over a traverse route from S16 to Dome Fuji, East Antarctica as measured by kinematic GNSS surveys in 2012-2013 and 2018-2019 (2021)
  • Author(s): Tsutaki Shun, Fukui Kotaro, Hattori Akihisa, Okuno Jun'ichi, Fujita Shuji, Kawamura Kenji
  • Journal Title: Polar Data Journal Volume: 5 Pages: -
  • DOI: 10.20575/00000033
  • Peer Reviewed / Open Access
• [Journal Article] Pure rotational Raman spectroscopy applied to N2/O2 analysis of air bubbles in polar firn (2021)
  • Author(s): Hiroshi Ohno, Yoshinori Iizuka, Shuji Fujita
  • Journal Title: Journal of Glaciology Volume: 67 Pages: 903
  • DOI: 10.1017/jog.2021.40
  • Peer Reviewed / Open Access
• [Journal Article] Antarctic shallow ice cores (NDF, NDFN, DFSE, DFNW) data: Density, chronology, permittivity, DEP, 0-20 m (2021)
  • Author(s): Fujita Shuji, Oyabu Ikumi, Kawamura Kenji, Nakazawa Fumio, Buizert Christo, Van Liefferinge Brice, Taylor Drew, Tsutaki Shun, Gogineni Prasad, Matsuoka Kenichi, Moholdt Geir, Abe-Ouchi Ayako, Awasthi Abhishek, Gallet Jean-Charles, Isaksson Elisabeth, Ohno Hiroshi, O'Neill Charles, Pattyn Frank, Sugiura Konosuke
  • Journal Title: Arctic Data archive System (ADS), Japan Volume: - Pages: -
  • DOI: 10.17592/001.2021102101
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Surface heights over a traverse route from S16 to Dome Fuji, East Antarctica as measured by kinematic GNSS surveys in 2012-2013 and 2018-2019 (2021)
  • Author(s): Tsutaki Shun, Fukui Kotaro, Hattori Akihisa, Okuno Jun'ichi, Fujita Shuji, Kawamura Kenji
  • Journal Title: Arctic Data archive System (ADS), Japan Volume: - Pages: -
  • DOI: 10.17592/001.2021082301
  • Peer Reviewed / Open Access
• [Journal Article] Ice thickness around Dome Fuji, Antarctica, based on JARE ground-based radar surveys: JARE54 data (2021)
  • Author(s): Tsutaki Shun, Fujita Shuji, Kawamura Kenji, Abe-Ouchi Ayako, Fukui Kotaro, Hoshina Yu, Nakazawa Fumio, Obase Takashi, Ohno Hiroshi, Oyabu Ikumi, Saito Fuyuki, Sugiura Konosuke, Suzuki Toshitaka
  • Journal Title: Arctic Data archive System (ADS), Japan Volume: - Pages: -
  • DOI: 10.17592/001.2021110907
  • Peer Reviewed / Open Access
• [Presentation] Causes and nature of deep radio echo internal layers at Dome Fuji- insights from site surveys of the 3rd DF deep ice core (2023)
  • Author(s): Shuji Fujita
  • Organizer: International Workshop on Ice Core Physics and Ice Sheet Dynamics (Onsen Meeting)
  • Int'l Joint Research
• [Presentation] Improvement of the dielectric tensor measurement as a method to measure density, 3D porous structure and crystal orientation fabric of ice cores: Realization of high spatial resolution measurement and its impacts (2023)
  • Author(s): Shuji Fujita, Tomotaka Saruya, Ryo Inoue
  • Organizer: International Workshop on Ice Core Physics and Ice Sheet Dynamics (Onsen Meeting)
  • Int'l Joint Research
• [Presentation] Formation of layered firn within near-surface depths around Dome Fuji, East Antarctica from physical and chemical analyses of multiple firn cores (2022)
  • Author(s): Ryo Inoue, Shuji Fujita, Kenji Kawamura, Motohiro Hirabayashi, Kumiko Goto-Azuma, Ikumi Oyabu, Fumio Nakazawa, Hideaki Motoyama
  • Organizer: The 13th Symposium on Polar Science, hosted by the National Institute of Polar Research (NIPR)
  • Int'l Joint Research
• [Presentation] Development of crystal orientation fabric in the Dome Fuji ice core in East Antarctica: implications for the deformation regime in ice sheets (2022)
  • Author(s): Tomotaka Saruya, Shuji Fujita, Yoshinori Iizuka, Atsushi Miyamoto, Hiroshi Ohno, Akira Hori, Wataru Shigeyama, Motohiro Hirabayashi, Kumiko Goto-Azuma
  • Organizer: The 13th Symposium on Polar Science, hosted by the National Institute of Polar Research (NIPR)
  • Int'l Joint Research
• [Presentation] Improvement of the dielectric tensor measurement as a method to measure density, 3D porous structure and crystal orientation fabric of ice cores: realization of high spatial resolution measurement and its impacts (2022)
  • Author(s): Shuji Fujita, Tomotaka Saruya, Ryo Inoue
  • Organizer: The 13th Symposium on Polar Science, hosted by the National Institute of Polar Research (NIPR), Nov 16, 2022
  • Int'l Joint Research
• [Presentation] Common preparation for quadrangular prism samples for physical property measurements and CFA (2022)
  • Author(s): Shuji Fujita, Tomotaka Saruya
  • Organizer: EGRIP Physical Property Consortium Meeting
  • Int'l Joint Research
• [Presentation] Improvement of the dielectric tensor measurement as a method to measure density, 3D porous structure and crystal orientation fabric of ice cores: realization of high spatial resolution measurement and its impacts (2022)
  • Author(s): Shuji Fujita, Tomotaka Saruya, Ryo Inoue
  • Organizer: International Partnership for Ice Core Sciences (IPICS) the 3rd Open Science Conference in Crans-Montana, Switzerland, Oct 2, 2022
  • Int'l Joint Research
• [Presentation] On formation of stratified firn near surface around Dome Fuji, East Antarctica, using physicochemical analyses (2022)
  • Author(s): Ryo Inoue, Shuji Fujita, Kenji Kawamura, Jun Ogata, Ayaka Yonekura, Kaori Fukuda, Kumiko Goto-Azuma, Motohiro Hirabayashi, Kyotaro Kitamura, Hideaki Motoyama, Fumio Nakazawa, Ikumi Oyabu
  • Organizer: International Partnership for Ice Core Sciences (IPICS) the 3rd Open Science Conference in Crans-Montana, Switzerland, Oct 2, 2022
  • Int'l Joint Research
• [Presentation] Dating of the ice core from south-east dome, Greenland (2022)
  • Author(s): Mahiro Sasage, Yoshinori Iizuka, Sakiko Ishino, Shuji Fujita, Kaoru Kawakami, Akira Hori, Takeshi Saito, Mai Matsumoto, Keita Takasugi, Sumito Matoba, Shohei Hattori, Ryu Uemura, Kazuho Horiuchi, Saaya Hamamoto
  • Organizer: International Partnership for Ice Core Sciences (IPICS) the 3rd Open Science Conference in Crans-Montana, Switzerland, Oct 2, 2022
  • Int'l Joint Research
• [Presentation] Development of crystal orientation fabric in the Dome Fuji ice core in East Antarctica: implications for the deformation regime in ice sheets (2022)
  • Author(s): Saruya, T, Fujita, S, Iizuka, Y, Miyamoto, A, Ohno, H, Hori, A, Shigeyama, W, Hirabayashi, M, Goto-Azuma, K
  • Organizer: International Partnership for Ice Core Sciences (IPICS) the 3rd Open Science Conference in Crans-Montana, Switzerland, Oct 2, 2022
  • Int'l Joint Research