Propagation of temperature/salinity variability in the mid-latitude Pacific

• Project/Area Number: 16K17800
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Meteorology/Physical oceanography/Hydrology
• Research Institution: Hokkaido University
• Principal Investigator: SASAKI YOSHINORI 北海道大学, 理学研究院, 准教授 (50604815)
• Project Period (FY): 2016-04-01 – 2020-03-31
• Project Status: Completed (Fiscal Year 2019)
• Budget Amount: ¥3,380,000 (Direct Cost: ¥2,600,000、Indirect Cost: ¥780,000); Fiscal Year 2018: ¥910,000 (Direct Cost: ¥700,000、Indirect Cost: ¥210,000); Fiscal Year 2017: ¥1,170,000 (Direct Cost: ¥900,000、Indirect Cost: ¥270,000); Fiscal Year 2016: ¥1,300,000 (Direct Cost: ¥1,000,000、Indirect Cost: ¥300,000)
• Keywords: 海洋物理・陸水学 / 十年スケール変動 / 中緯度海洋 / サブダクション

Outline of Final Research Achievements

Subduction and migration of density-compensated temperature and salinity water-mass anomalies on isopycnals are examined in the subtropical gyre of the South Pacific using an observational dataset. The present results demonstrate that density-compensated anomalies are found to follow two pathways from the subtropical region to the tropical region. It is revealed that the advection by the South Equatorial Countercurrent (SECC) divides these two pathways. Hence, SECC plays a key role in determining whether a density-compensated anomaly propagates through the interior region or the western boundary region.

Academic Significance and Societal Importance of the Research Achievements

本研究で得られた結果は，海洋内部の等密度面上の水温・塩分変動は，海洋内部の海流の構造を強く反映していることを示している．また南赤道反流は風応力により駆動され海洋上層のみに存在する比較的弱い海流であり，空間解像度の低い観測データや数値モデルでは，その東西方向の分布がうまく再現されない．したがって，数値モデルを用いて中緯度海洋の熱帯域への影響を正しく見積もるには，南赤道反流の再現が重要であることを示唆する．

Research Products

• [Int'l Joint Research] ハワイ大国際太平洋研究センター(米国)
• [Journal Article] Atmospheric response to interannual variability of sea surface temperature front in the East China Sea in early summer (2018)
  • Author(s): Yoshi N. Sasaki and Yamada Yuko
  • Journal Title: Climate Dynamics Volume: 印刷中 Issue: 7-8 Pages: 2509-2522
  • DOI: 10.1007/s00382-017-4025-y
  • Peer Reviewed
• [Journal Article] Interannual to decadal variability of the upper-ocean heat content in the western North Pacific and its relationship to oceanic and atmospheric variability (2018)
  • Author(s): Hanna Na, K.-Y. Kim, Shoshiro Minobe, and Yoshi N. Sasaki
  • Journal Title: Journal of Climate Volume: 印刷中 Issue: 13 Pages: 5107-5125
  • DOI: 10.1175/jcli-d-17-0506.1
  • Peer Reviewed / Int'l Joint Research
• [Presentation] Two pathways of subsurface spiciness anomalies in the subtropical South Pacific (2020)
  • Author(s): Sasaki Y. N. and Y. Iwai
  • Organizer: 2020 Ocean Sciences Meeting
  • Int'l Joint Research
• [Presentation] Observations of spiciness anomaly propagation in the South Pacific (2018)
  • Author(s): Sasaki Y. N. and Y. Iwai
  • Organizer: ISEE Workshop
  • Int'l Joint Research
• [Presentation] Decadal variability of the Kuroshio extension in a high-resolution ocean-atmosphere coupled model (2018)
  • Author(s): Sasaki, Y. N., R. Kimura and S. P. Bishop
  • Organizer: JpGU Meeting 2018
  • Int'l Joint Research
• [Presentation] Atmospheric Response to Interannual Variability of Sea Surface Temperature Front in the East China Sea in Early Summer (2018)
  • Author(s): Sasaki, Y. N., and Y. Yamada
  • Organizer: 2018 Ocean Sciences Meeting
  • Int'l Joint Research
• [Presentation] 高解像度大気海洋結合モデルによる黒潮続流の10年変動の解析． 2017年度日本海洋学会秋季大会 (2017)
  • Author(s): 木村 亮介，佐々木 克徳，S. P. Bishop
  • Organizer: 2017年度日本海洋学会秋季大会
• [Presentation] Argoデータによる南太平洋亜熱帯域から熱帯域へのspiciness偏差の伝播 (2017)
  • Author(s): 佐々木 克徳，岩井 悠馬
  • Organizer: 2017年度日本海洋学会秋季大会
• [Presentation] Trend of surface to subsurface salinity in the South Pacific from Argo observation (2016)
  • Author(s): Y. Iwai, and Y. N. Sasaki
  • Organizer: The 19th Hokkaido University-Seoul National University Joint Symposium
  • Place of Presentation: 北海道大学(北海道・札幌市)
  • Year and Date: 2016-11-25
  • Int'l Joint Research
• [Presentation] 梅雨期の東シナ海黒潮における大気海洋相互作用の船舶観測(その2) (2016)
  • Author(s): 佐々木 克徳, 森 信行, 見延 庄士郎, 中村 啓彦, 仁科 文子, 岩﨑 慎介, 磯辺 篤彦
  • Organizer: 2016年度日本海洋学会秋季大会
  • Place of Presentation: 鹿児島大学(鹿児島県・鹿児島市)
  • Year and Date: 2016-09-12