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Dynamics of the Ryukyu Current System and its role in the material circulation in the North Pacific

Research Project

Project/Area Number 15H03725
Research Category

Grant-in-Aid for Scientific Research (B)

Allocation TypeSingle-year Grants
Section一般
Research Field Meteorology/Physical oceanography/Hydrology
Research InstitutionKagoshima University

Principal Investigator

Nakamura Hirohiko  鹿児島大学, 農水産獣医学域水産学系, 教授 (50284914)

Co-Investigator(Kenkyū-buntansha) 仁科 文子  鹿児島大学, 農水産獣医学域水産学系, 助教 (80311885)
加古 真一郎  鹿児島大学, 理工学域工学系, 助教 (60709624)
ナ ハンナ  北海道大学, 理学(系)研究科(院), その他 (40726171)
Research Collaborator Zhu Xiao-Hua  
Park Jae-Hun  
Min Hong Sik  
Na Hanna  
Project Period (FY) 2015-04-01 – 2019-03-31
Project Status Completed (Fiscal Year 2018)
Budget Amount *help
¥17,420,000 (Direct Cost: ¥13,400,000、Indirect Cost: ¥4,020,000)
Fiscal Year 2018: ¥2,860,000 (Direct Cost: ¥2,200,000、Indirect Cost: ¥660,000)
Fiscal Year 2017: ¥2,860,000 (Direct Cost: ¥2,200,000、Indirect Cost: ¥660,000)
Fiscal Year 2016: ¥2,990,000 (Direct Cost: ¥2,300,000、Indirect Cost: ¥690,000)
Fiscal Year 2015: ¥8,710,000 (Direct Cost: ¥6,700,000、Indirect Cost: ¥2,010,000)
Keywords琉球海流 / 黒潮 / 中規模渦 / 季節変動 / 北太平洋中層水 / 栄養塩 / 琉球海流系 / 経年変動 / 係留観測 / 国際共同観測 / 北太平洋午子面循環 / JCRYCSS / JKRYCSS / 北太平洋子午面循環
Outline of Final Research Achievements

The main results are as follows: 1) The Ryukyu Current was observed in its upstream area through the Japan, China and Korea joint collaboration research. As a result, a quasi-permanent undercurrent with a ~20 cm/s velocity core was identified at ~500 m depth. The intensity of this velocity core was not affected by impingements of westward-propagating mesoscale eddies, suggesting that the undercurrent, i.e., the Ryukyu Current, is not an organization of such eddy impingements. This result was supported by the analysis of a mesoscale eddy trucking dataset. 2) Based on data analysis and numerical experiments, the reason why seasonal velocity variations of the Kuroshio and Ryukyu Current are out of phase was clarified. Namely, the local process due to the East Asian Monsoon is responsible for the seasonal velocity variation of the upper-layer Kuroshio, while the remote process due to the curl of interior wind stresses is responsible for that of the lower-layer Kuroshio and Ryukyu Current.

Academic Significance and Societal Importance of the Research Achievements

琉球海流の形成理論については,筆者らが提案した陸棚波理論(Nakamura et al., 2007)は存在するものの,中規模渦が琉球海流の形成に寄与しているか否かという基本的な問いは未解決であった。本研究の結果は,源流域の琉球海流の形成に,同緯度帯を西進してくる中規模渦は寄与していないことを示しており,形成理論を確立する上で大きな前進をもたらしたと言える。さらに,黒潮と琉球海流の流速の季節変動研究から,黒潮の表層流速の季節変動に対する東アジアモンスーンの重要性が指摘され,黒潮研究の新たなパラダイムを開拓した。これらの2点は,海洋物理学における大きな学術的意義と言える。

Report

(5 results)
  • 2018 Annual Research Report   Final Research Report ( PDF )
  • 2017 Annual Research Report
  • 2016 Annual Research Report
  • 2015 Annual Research Report
  • Research Products

    (43 results)

All 2019 2018 2017 2016 2015 Other

All Int'l Joint Research (8 results) Journal Article (6 results) (of which Int'l Joint Research: 4 results,  Peer Reviewed: 6 results) Presentation (28 results) (of which Int'l Joint Research: 14 results,  Invited: 2 results) Book (1 results)

  • [Int'l Joint Research] SIO(中国)

    • Related Report
      2018 Annual Research Report
  • [Int'l Joint Research] KIOST/Inha University/Souel National University(韓国)

    • Related Report
      2018 Annual Research Report
  • [Int'l Joint Research] SIO, State Ocean Administration(中国)

    • Related Report
      2017 Annual Research Report
  • [Int'l Joint Research] KIOST/Inha Univ.(韓国)

    • Related Report
      2017 Annual Research Report
  • [Int'l Joint Research] SIO, State Oceanic Administration(中国)

    • Related Report
      2016 Annual Research Report
  • [Int'l Joint Research] KIOST/Inha Univ.(韓国)

    • Related Report
      2016 Annual Research Report
  • [Int'l Joint Research] SOI, SOA(China)

    • Related Report
      2015 Annual Research Report
  • [Int'l Joint Research] KIOST(韓国)

    • Related Report
      2015 Annual Research Report
  • [Journal Article] Tidal and residual currents across the northern Ryukyu Island chain observed by ferryboat ADCP2017

    • Author(s)
      Liu Zhao-Jun、Nakamura Hirohiko、Zhu Xiao-Hua、Nishina Ayako、Dong Menghong
    • Journal Title

      Journal of Geophysical Research: Oceans

      Volume: 122 Issue: 9 Pages: 7198-7217

    • DOI

      10.1002/2017jc012876

    • Related Report
      2017 Annual Research Report
    • Peer Reviewed / Int'l Joint Research
  • [Journal Article] 黒潮の流路・流量変動の研究─源流域から九州東岸まで─2017

    • Author(s)
      中村啓彦
    • Journal Title

      海の研究

      Volume: 26 Pages: 113-147

    • NAID

      130007482641

    • Related Report
      2017 Annual Research Report
    • Peer Reviewed
  • [Journal Article] Tidal currents and Kuroshio transport variations in the Tokara Strait estimated from ferryboat ADCP data2017

    • Author(s)
      Zhu, X.-H., H. Nakamura, M. Dong, A. Nishina, and T. Yamashiro
    • Journal Title

      Journal of Geophysical Research-Oceans

      Volume: 122 Issue: 3 Pages: 2120-2142

    • DOI

      10.1002/2016jc012329

    • Related Report
      2016 Annual Research Report
    • Peer Reviewed / Int'l Joint Research
  • [Journal Article] Deep ventilation in the Okinawa Trough induced by Kerama Gap overflow2016

    • Author(s)
      Nishina, A., H. Nakamura, J.-H. Park, D. Hasegawa, Y. Tanaka, S. Seo, and T. Hibiya
    • Journal Title

      Journal of Geophysical Research

      Volume: 121 Issue: 8 Pages: 6092-6102

    • DOI

      10.1002/2016jc011822

    • Related Report
      2016 Annual Research Report
    • Peer Reviewed / Int'l Joint Research
  • [Journal Article] Seasonal cycle of volume transport through Kerama Gap revealed by a 20-year global HYbrid Coordinate Ocean Model reanalysis2015

    • Author(s)
      Yu, Z., E. J. Metzger, P. Thoppil, H. E. Hurlburt, L. Zamudio, O. M. Smedstad, H. Na, H. Nakamura, J.-H. Park
    • Journal Title

      Ocean Modelling

      Volume: 96 Pages: 203-213

    • DOI

      10.1016/j.ocemod.2015.10.012

    • Related Report
      2015 Annual Research Report
    • Peer Reviewed / Int'l Joint Research
  • [Journal Article] Local wind effect on the Kuroshio path state off the southeastern coast of Kyushu2015

    • Author(s)
      Nakamura H., R. Hiranaka, A. Daisuke, and T. Saito,
    • Journal Title

      Journal of Oceanography

      Volume: 71 Issue: 5 Pages: 575-596

    • DOI

      10.1007/s10872-015-0309-1

    • Related Report
      2015 Annual Research Report
    • Peer Reviewed
  • [Presentation] The Joint Kuroshio-Ryukyu Current System Study and a rapid report about mooring observations southeast of Miyakojima2019

    • Author(s)
      Zhu, X.-H., H. Nakamura, J.-H. Park, R. Zhao, A. Nishina, C. Zhang, C. Jeon, H. Na, Z.-N. Zhu, H.-S. Min
    • Organizer
      JpGU Meeting 2019
    • Related Report
      2018 Annual Research Report
    • Int'l Joint Research
  • [Presentation] Characteristics of water in the southern Okinawa Trough2019

    • Author(s)
      Nishina, A., H. Nakamuara, J.-H. Park, X.-H. Zhu, H.-S. Min, and H. Na
    • Organizer
      JpGU Meeting 2019
    • Related Report
      2018 Annual Research Report
    • Int'l Joint Research
  • [Presentation] Impact of the mesosacle eddies on the western boundary current over the entire western North Pacific2019

    • Author(s)
      Kako S., and H. Nakamuar
    • Organizer
      JpGU Meeting 2019
    • Related Report
      2018 Annual Research Report
    • Int'l Joint Research
  • [Presentation] A numerical study on the dynamics of seasonal velocity variation in the East China Sea2019

    • Author(s)
      Zhang, Z.-L., H. Nakamura, and Zhu X.-H
    • Organizer
      JpGU Meeting 2019
    • Related Report
      2018 Annual Research Report
    • Int'l Joint Research
  • [Presentation] Temporal and spatial velocity variations over the Kuroshio Extension, Kuroshio and Ryukyu Current System in 1982-20142019

    • Author(s)
      Qiao, Y., H. Nakamura, and A, Nishina
    • Organizer
      JpGU Meeting 2019
    • Related Report
      2018 Annual Research Report
    • Int'l Joint Research
  • [Presentation] Structure and variability of the Kuroshio current in the Tokara Strait2019

    • Author(s)
      Z. Liu, H. Nkamaura, X.-H. Zhu, A. Nishina, X. Guo, and M. Dong
    • Organizer
      JpGU Meeting 2019
    • Related Report
      2018 Annual Research Report
    • Int'l Joint Research
  • [Presentation] Near-inertial waves advected by the Kuroshio from observation and simulation2019

    • Author(s)
      Jeon, C., J.-H. Park, H. Nakamura, A. Nishina, X.-H. Zhu, D.-G. Kim, H.-S. Min, S.-K. Kang, H. Na, N. Hirose, and Y. Choi
    • Organizer
      JpGU Meeting 2019
    • Related Report
      2018 Annual Research Report
    • Int'l Joint Research
  • [Presentation] Bottom Pressure in the East China Sea -Observation and modeling2019

    • Author(s)
      Zheng, H., X.-H. Zhu, H. Nakamura, J.-H. Park, C. Jeon, R. Zhao, A. Nishina, C. Zhang, H. Na, Z.-N. Zhu, H.-S. Min
    • Organizer
      JpGU Meeting 2019
    • Related Report
      2018 Annual Research Report
    • Int'l Joint Research
  • [Presentation] Relationship of the Kuroshio with the current fields in the East China Sea from observations and model results2019

    • Author(s)
      Min, H.-S., C. Hwang, D.-G. Kim, H. Nakamura, A. Nishina, X.-H. Zhu, J.-H. Park, C. Jeon, H. Na, and N. Hirose
    • Organizer
      JpGU Meeting 2019
    • Related Report
      2018 Annual Research Report
    • Int'l Joint Research
  • [Presentation] Seasonal variation of near-inertial internal wave energy and associated water masses modification in the Okinawa Trough2018

    • Author(s)
      Nakamura, H., N. Kudo, A. Nishina, and T. Nakano
    • Organizer
      JpGU Meeting 2018
    • Related Report
      2018 Annual Research Report
    • Int'l Joint Research
  • [Presentation] 沖縄トラフ中深層の栄養塩輸送2018

    • Author(s)
      仁科文子,中村啓彦,横川太一,川口慎介
    • Organizer
      JpGU Meeting 2018
    • Related Report
      2018 Annual Research Report
  • [Presentation] Seasonal velocity variation over the entire Kuroshio path -Data analysis and numerical simulation -2018

    • Author(s)
      Zhang, Z.-l., H. Nakamura, and X.-H., Zhu
    • Organizer
      日本海洋学会2018年度秋季大会
    • Related Report
      2018 Annual Research Report
  • [Presentation] 九州南方海域の亜表層に出現する低塩分水塊の分布と移流経路2018

    • Author(s)
      米森陽祐,仁科文子,中村啓彦,長谷川大介
    • Organizer
      日本海洋学会2018年度秋季大会
    • Related Report
      2018 Annual Research Report
  • [Presentation] Microstructure and mooring observations in the Kerama Gap2018

    • Author(s)
      Inoue, R., H. Nakamura, T. Tanaka, and I. Yasuda
    • Organizer
      2018 Ocean Science Meeting
    • Related Report
      2017 Annual Research Report
    • Int'l Joint Research
  • [Presentation] Seasonal change in vertical mixing inferred from water-mass modification along PN repeat hydrographic section in East China Sea2017

    • Author(s)
      Kudo, N., H. Nakamura, A. Nishina, and T. Nakano
    • Organizer
      International Symposium “Ocean Mixing Processes: Impact on Biogeochemistry, Climate and Ecosystem”
    • Place of Presentation
      東京大学(東京都・文京区)
    • Year and Date
      2017-03-16
    • Related Report
      2016 Annual Research Report
  • [Presentation] Seasonal transport variaiton over the entire Kuroshio region2017

    • Author(s)
      Zhenlong Zhang and Hirohiko Nakamura
    • Organizer
      JpGU-AGU joint meeting 2017
    • Related Report
      2017 Annual Research Report
    • Int'l Joint Research
  • [Presentation] 沖縄トラフ北部の近慣性内部波エネルギー、乱流混合、水塊特性の季節変動2017

    • Author(s)
      中村啓彦
    • Organizer
      2017年度九州沖縄地区合同シンポジウム「乱流混合と海洋環境」
    • Related Report
      2017 Annual Research Report
  • [Presentation] 東シナ海の黒潮と琉球海流系の観測 ―変動特性から生物生産まで―2017

    • Author(s)
      中村啓彦
    • Organizer
      国立科学博物館 総合研究黒潮グループ勉強会
    • Related Report
      2017 Annual Research Report
    • Invited
  • [Presentation] KH-16-7ケラマ海裂における観測速報2017

    • Author(s)
      中村啓彦,安田一郎
    • Organizer
      東京大学大気海洋研究所共同利用研究集会
    • Place of Presentation
      東京大学大気海洋研究所(千葉県・柏市)
    • Related Report
      2016 Annual Research Report
  • [Presentation] 黒潮流路・流量の季節変動の研究 ―源流域から日本南岸まで―2017

    • Author(s)
      中村啓彦
    • Organizer
      東京大学大気海洋研究所共同利用研究集会
    • Place of Presentation
      東京大学大気海洋研究所(千葉県・柏市)
    • Related Report
      2016 Annual Research Report
  • [Presentation] 季節風が励起する台湾北東沖の黒潮小蛇行の数値実験2016

    • Author(s)
      平中陸・中村啓彦
    • Organizer
      日本海洋学会2016年度春季大会
    • Place of Presentation
      東京大学本郷キャンパス(東京都文京区)
    • Year and Date
      2016-03-15
    • Related Report
      2015 Annual Research Report
  • [Presentation] Seasonality of the entire Kuroshio in the velocity field2016

    • Author(s)
      Zhang, Z., H. Nakamura, D. Ambe, R. Hiranaka, and T. Saito
    • Organizer
      日本海洋学会2016年度春季大会
    • Place of Presentation
      東京大学本郷キャンパス(東京都文京区)
    • Year and Date
      2016-03-15
    • Related Report
      2015 Annual Research Report
  • [Presentation] 南西諸島周辺海域の海水循環,乱流混合と物質循環2016

    • Author(s)
      中村啓彦・仁科文子
    • Organizer
      水産海洋シンポジウム
    • Place of Presentation
      東京大学本郷キャンパス(東京都文京区)
    • Year and Date
      2016-03-14
    • Related Report
      2015 Annual Research Report
  • [Presentation] 西岸境界域での北太平洋中層水の変質過程2016

    • Author(s)
      楊季蓮・中村啓彦・張振龍
    • Organizer
      日本海洋学会2016年度春季大会
    • Place of Presentation
      東京大学本郷キャンパス(東京都文京区)
    • Year and Date
      2016-03-14
    • Related Report
      2015 Annual Research Report
  • [Presentation] Studies on the current system around the Okinawa Trough using Training Ship Kagoshima-maru2016

    • Author(s)
      Nakamura, H.
    • Organizer
      Workshop on Typhoon-Ocean Interaction in the Northwest Pacific, Isabu Typhoon/Ocean Program
    • Place of Presentation
      Seoul、Korea
    • Year and Date
      2016-02-02
    • Related Report
      2015 Annual Research Report
    • Int'l Joint Research / Invited
  • [Presentation] 加古真一郎,田井益美,中村啓彦,高山勝己2016

    • Author(s)
      FORA-WNP30を用いた琉球海流の時空間変動特性に関する研究
    • Organizer
      日本海洋学会2016年度秋季大会
    • Place of Presentation
      鹿児島大学(鹿児島県・鹿児島市)
    • Related Report
      2016 Annual Research Report
  • [Presentation] Seasonal variation of the Kuroshio and its relationship with local wind stress2015

    • Author(s)
      Zhang, Z., H. Nakamura, D. Ambe, R. Hiranaka, and T. Saito
    • Organizer
      日本海洋学会2015年度秋季大会
    • Place of Presentation
      愛媛大学(愛媛県松山市)
    • Year and Date
      2015-09-29
    • Related Report
      2015 Annual Research Report
  • [Presentation] Local wind effect on the Kuroshio path state off the southeastern coast of Kyushu2015

    • Author(s)
      Nakamura, H., R. Hiranaka, D. Ambe, and T. Saito
    • Organizer
      18th Pacific-Asian Marginal Seas Meeting
    • Place of Presentation
      那覇市ぶんかテンブス館(沖縄県那覇市)
    • Year and Date
      2015-04-21
    • Related Report
      2015 Annual Research Report
    • Int'l Joint Research
  • [Book] 鹿児島の島々―文化と社会・産業・自然―: 第20章 黒潮2016

    • Author(s)
      中村啓彦
    • Total Pages
      291
    • Publisher
      南方新社
    • Related Report
      2015 Annual Research Report

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Published: 2015-04-16   Modified: 2022-08-30  

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