Study of decadal to multi-decadal variability in ocean by using 4-dimensional variational data assimilation method

2015 Fiscal Year Final Research Report

• Project/Area Number: 25800269
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Meteorology/Physical oceanography/Hydrology
• Research Institution: Japan Agency for Marine-Earth Science and Technology
• Principal Investigator: OSAFUNE Satoshi 国立研究開発法人海洋研究開発機構, 地球環境観測研究開発センター, 技術研究員 (50638723)
• Research Collaborator: MASUDA Shuhei ; SUGIURA Nozomi ; DOI Toshimasa
• Project Period (FY): 2013-04-01 – 2016-03-31
• Keywords: 北太平洋 / 長期変動 / データ同化 / 太平洋十年規模振動 / 潮汐18.6年振動

Outline of Final Research Achievements

By using a state-of-the-art four-dimensional variational data assimilation system, and a long-term ocean state estimation data set produced by the system, I investigated long-term ocean variability in the mid-to-high-latitude North Pacific, its underlying mechanisms, and its influence on climate. I evaluated the applicability of the data set for climate research, and suggested that the subsurface signal of the Pacific Decadal Oscillation (PDO) is related to the variation in formation of mode waters. In addition, I conducted a comparative numerical experiment using the system, and showed that the 18.6-year modulation of the localized strong tidal mixing can significantly contribute to the sea surface temperature anomalies related to PDO. These results leads to better understanding of the importance of the mid-to-high-latitude ocean in climate system.

Free Research Field

海洋物理