Geodetic, physical oceanographic, and seismological study of the Japan Sea

• Project/Area Number: 17K05621
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Solid earth and planetary physics
• Research Institution: Hokkaido University
• Principal Investigator: Heki Kosuke 北海道大学, 理学研究院, 教授 (30280564)
• Project Period (FY): 2017-04-01 – 2020-03-31
• Project Status: Completed (Fiscal Year 2019)
• Budget Amount: ¥4,030,000 (Direct Cost: ¥3,100,000、Indirect Cost: ¥930,000); Fiscal Year 2019: ¥1,300,000 (Direct Cost: ¥1,000,000、Indirect Cost: ¥300,000); Fiscal Year 2018: ¥1,170,000 (Direct Cost: ¥900,000、Indirect Cost: ¥270,000); Fiscal Year 2017: ¥1,560,000 (Direct Cost: ¥1,200,000、Indirect Cost: ¥360,000)
• Keywords: 日本海 / GRACE / 衛星海面高度計 / GNSS / 季節変化 / 日本海東縁地震 / 海底圧力変化 / アルゴフロート / 海面高度計 / 重力衛星 / 日本海東縁 / 地震活動 / 海水荷重変動 / 衛星重力計測 / 地震発生の季節性 / 季節的地殻変動 / 重力時間変化 / Argo float / 永年変化 / 年周地殻変動 / 重力 / 地殻変動 / 地震

Outline of Final Research Achievements

I developed a technique to combine various sensors for a particula sea, such as the satellite gravimetry (GRACE satellites), ocean altimetry (e.g. JASON satellites), and Algo Float for in-situ measurements of the sea water temperature and salinity profiles. Combination of these data enables us to discern if the observed sea level change comes from thermosteric changes or real ocean mass changes (ocean bottom pressure changes). These results were verified by comparing with seasonal or secular crustal movements measured by global navigation satellite system (GNSS) receivers deployed near the coast of the studied oceanic area. I applied the method to the Sea of Japan and the Gulf of Carpentaria, northern Australian coast, and found significant seasonal oceanic mass changes in these oceanic areas.

Academic Significance and Societal Importance of the Research Achievements

日本海の海面高が20cmを超える季節変化を見せることは験潮儀等のデータから知られていた。本研究では重力衛星による海水質量計測、衛星海面高度計による海面高計測、その場観測による海水の熱膨張の推定、の三者を組み合わせてその原因を探り、日本海の海面高の季節変化はその大部分が熱膨張によるものであることを示した。しかし衛星重力データはわずかながらも有意な海水質量の季節変化を示し、それに起因する海底圧力変化が日本海東縁で発生する逆断層地震が初夏に集中する原因である可能性を示した。同様の手法をオーストラリア北部カーペンタリア湾に応用し、大きな海面高季節変化が季節風の吹き寄せによるものであることを解明した。

Research Products

• [Journal Article] Heterogeneous oceanic mass distribution in GRACE observations and its leakage effect (2020)
  • Author(s): Yi, S. and K. Heki
  • Journal Title: Geophysical Journal International Volume: 221 Issue: 1 Pages: 603-616
  • DOI: 10.1093/gji/ggaa022
  • NAID: 120006960644
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Substantial meltwater contribution to the Brahmaputra revealed by satellite gravimetry (2019)
  • Author(s): Yi, S., C. Song, K. Heki, S. Kong, Q. Wang, and L. Chang
  • Journal Title: The Cryosphere Discuss Volume: -
  • DOI: 10.5194/tc-2019-211
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] The potential of GRACE gravimetry to detect the heavy rainfall-induced impoundment of a small reservoir in the upper Yellow River (2017)
  • Author(s): Yi, S., C. Song, Q. Wang, K. Heki, and W. Sun
  • Journal Title: Water Resources Research Volume: 53 Issue: 8 Pages: 6562-6578
  • DOI: 10.1002/2017wr020793
  • NAID: 120006382302
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Acceleration in the global sea level rise: 2005-2016 (2017)
  • Author(s): Yi, S., K. Heki, and Q. Qian
  • Journal Title: Geophysical Research Letters Volume: 44 Issue: 23 Pages: 11905-11913
  • DOI: 10.1002/2017gl076129
  • Peer Reviewed / Int'l Joint Research
• [Presentation] Geodesy sharpens you up (2019)
  • Author(s): Kosuke Heki
  • Organizer: International Union of Geodesy and Geophysics 総会
  • Int'l Joint Research / Invited
• [Presentation] オーストラリア北側の海洋での海水準変動について (2019)
  • Author(s): 徳井雄太、日置幸介
  • Organizer: 日本地球惑星科学連合講演会
• [Presentation] Sea level in northern Australian coast (2019)
  • Author(s): Tokui, Y. and K. Heki
  • Organizer: International Union of Geodesy and Geophysics 総会
  • Int'l Joint Research
• [Presentation] オーストラリア北側海域の海面高度および海水質量の変化 (2019)
  • Author(s): 徳井雄太、日置幸介
  • Organizer: 日本測地学会秋季講演会
• [Presentation] Seasonal crustal deformation in NE Japan and sea level budget of the Japan Sea (2018)
  • Author(s): Kosuke Heki
  • Organizer: American Geophysical Union, 2018 Fall Meeting
  • Int'l Joint Research
• [Presentation] 日本海のSea Level Budget: GRACEとArgoと海面高度計 (2018)
  • Author(s): 日置幸介
  • Organizer: 日本地球惑星科学連合講演会
• [Presentation] 潮位と地殻変動：宇宙技術で何が変わったか (2018)
  • Author(s): 日置幸介
  • Organizer: 2017年度地殻変動研究集会
• [Presentation] Water mass variation in the Japan Sea from satellite gravimetry: Comparison with seasonal movements of GNSS stations (2017)
  • Author(s): Doto, S. and K. Heki
  • Organizer: Japan Geoscience Union, 2017 Meeting (joint with American Geophysical Union)
  • Int'l Joint Research
• [Presentation] Seasonal water mass variation in the Japan Sea from satellite gravimetry: Comparison with GNSS and seasonality in earthquake occurrences (2017)
  • Author(s): Doto, S. and K. Heki
  • Organizer: IAG-IASPEI 2017 Joint Scientific Assembly
  • Int'l Joint Research
• [Presentation] 東北日本の季節的地殻変動再訪：日本海の海水荷重と積雪荷重の変動 (2017)
  • Author(s): 日置幸介、道藤俊
  • Organizer: 日本測地学会周期講演会
• [Book] 図説 地球科学の事典 第5-6章 地球重力場と時間変化 (2018)
  • Author(s): 鳥海光弘他多数(研究代表者の日置幸介を含む）
  • Total Pages: 248
  • Publisher: 朝倉書店
  • ISBN: 9784254160727
• [Book] 動く地球の測りかた (2017)
  • Author(s): 河野宣之、日置幸介
  • Total Pages: 124
  • Publisher: 東海大学出版部
  • ISBN: 9784486021285