Ocean heat content variability in the western tropical Pacific region through the Mid-Pleistocene climate transition

• Project/Area Number: 15K21221
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Environmental dynamic analysis; Stratigraphy/Paleontology
• Research Institution: Kanazawa University
• Principal Investigator: Sagawa Takuya 金沢大学, 自然システム学系, 助教 (40448395)
• Project Period (FY): 2015-04-01 – 2018-03-31
• Project Status: Completed (Fiscal Year 2017)
• Budget Amount: ¥4,030,000 (Direct Cost: ¥3,100,000、Indirect Cost: ¥930,000); Fiscal Year 2017: ¥910,000 (Direct Cost: ¥700,000、Indirect Cost: ¥210,000); Fiscal Year 2016: ¥1,430,000 (Direct Cost: ¥1,100,000、Indirect Cost: ¥330,000); Fiscal Year 2015: ¥1,690,000 (Direct Cost: ¥1,300,000、Indirect Cost: ¥390,000)
• Keywords: 熱帯太平洋 / 第四紀 / 古水温復元 / 浮遊性有孔虫 / 氷期－間氷期サイクル / 赤道太平洋暖水塊 / マグネシウム／カルシウム / 古海洋学

Outline of Final Research Achievements

Calcification depth of planktonic foraminifera, Pulleniatina obliquiloculata, is estimated using sediment trap samples moored in the central and western equatorial Pacific. It is confirmed that Mg/Ca thermometry of this species is useful for reconstructing thermocline temperature in this regions. Past sea surface and thermocline temperatures were reconstructed by Mg/Ca thermometry of two planktonic foraminiferal species using a sediment core retrieved from the Ontong Java Plateau. Reconstructed temperatures showed glacial-interglacial change as well as variability in much longer timescale. The results suggest that the ocean-atmosphere interaction played significant role in long-term temperature regulation in the western tropical Pacific region.

Research Products

• [Int'l Joint Research] Rutgers University/University of Hawaii(米国)
• [Int'l Joint Research] University of Hawaii(米国)
• [Journal Article] International Ocean Discovery Program Expedition 363 Preliminary Report, Western Pacific Warm Pool ~Neogene and Quaternary records of Western Pacific Warm Pool paleoceanography~ (2017)
  • Author(s): Yair Rosenthal, Ann E. Holbourn, Denise K. Kulhanek, Takuya Sagawa, and the Expedition 363 Scientists
  • Journal Title: IODP Preliminary Report Volume: －
  • DOI: 10.14379/iodp.pr.363.2017
  • Open Access / Int'l Joint Research
• [Journal Article] Evolution of the North Pacific Subtropical Gyre during the past 190kyr through the interaction of the Kuroshio Current with the surface and intermediate waters (2016)
  • Author(s): Yurika Ujiie, Hirofumi Asahi, Takuya Sagawa, and Franck Bassinot
  • Journal Title: Paleoceanography Volume: - Issue: 11 Pages: 1498-1513
  • DOI: 10.1002/2015pa002914
  • Peer Reviewed / Int'l Joint Research
• [Presentation] 温室効果ガスの放射強制力に応答した西太平洋暖水塊の表層水温変動 (2018)
  • Author(s): 佐川 拓也、向田 圭佑、山崎 俊嗣、久保田 好美、黒田 潤一郎
  • Organizer: 日本地球惑星科学連合2018年大会
• [Presentation] Different CO2 history recorded in boron isotope ratio of two surface dwelling planktonic foraminifers (2018)
  • Author(s): K. Kubota, Y. Yokoyama, T. Ishikawa, T. Sagawa, M. Ikehara, T. Yamazaki
  • Organizer: Goldschmidt 2018
  • Int'l Joint Research
• [Presentation] Did the western equatorial Pacific contribute to atmospheric CO2 rise during the last deglaciation? (2017)
  • Author(s): K. Kubota, Y. Yokoyama, T. Ishikawa, T. Sagawa, and T. Yamazaki
  • Organizer: Goldschmidt 2017
  • Int'l Joint Research
• [Presentation] Mg/Ca of planktonic foraminifer Pulleniatina obliquiloculata as a thermocline temperature proxy: results from sediment trap experiments in the equatorial Pacific (2017)
  • Author(s): T. Sagawa, T. Saito, T. Irino
  • Organizer: AGU 2017 Fall Meeting
  • Int'l Joint Research
• [Presentation] Deglacial Western Equatorial Pacific pCO2 Reconstruction Using Boron Isotopes of Planktonik Foraminiferas (2017)
  • Author(s): K. Kubota, Y. Yokoyama, T. Ishikawa, T. Sagawa, M. Ikehara, T. Yamazaki
  • Organizer: AGU 2017 Fall Meeting
  • Int'l Joint Research