Mechanism of rapid sea surface temperature warming in the Kuroshio region and its impact on coastal environment

2022 Fiscal Year Final Research Report

• Project/Area Number: 19K03978
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 17020:Atmospheric and hydrospheric sciences-related
• Research Institution: Japan, Meteorological Research Institute
• Principal Investigator: Usui Norihisa 気象庁気象研究所, 全球大気海洋研究部, 主任研究官 (50370333)
• Co-Investigator(Kenkyū-buntansha): 広瀬 成章 気象庁気象研究所, 全球大気海洋研究部, 研究官 (20748074)
• Project Period (FY): 2019-04-01 – 2023-03-31
• Keywords: 黒潮 / 対馬暖流 / 水温上昇 / 大蛇行 / 東シナ海 / 日本海貯熱量 / 沿岸水位 / 急潮

Outline of Final Research Achievements

Focusing on variations and interrelationships of the Kuroshio, its extension (KE), and the Tsushima Warm Current, and their effects on water temperature changes around Japan including coastal waters and marginal seas, the followings are clarified. (1) A remarkable warming trend of subsurface temperature over the East China Sea leads to enhanced latent heat release during summer. (2) The recent low Kuroshio transport results in the historical long-duration Kuroshio large meander in 2017. (3) The relationship between the Kuroshio and the past unusually high sea-level events at the south coast of Japan. (4) Synchronized variation mechanism of KE, Japanese coastal sea level, Tsushima Warm Current, and the ocean heat content in the Japan Sea. (5) The mechanism of Kyucho events at Cape Muroto and the Echizen Coast, and its relationship with the Kuroshio and the Tsushima Warm Current, respectively.

Free Research Field

海洋物理学

Academic Significance and Societal Importance of the Research Achievements

東シナ海の亜表層水温の顕著な高温化と夏季潜熱放出の強化は、九州周辺の豪雨に寄与している可能性があり、気象予測や防災情報の高度化に資する。これまで個々に研究されてきた、黒潮、黒潮続流、対馬暖流を結びつけるメカニズムを提案し、日本沿岸水位も含めて3つの海流系を統合した新たな見方を提示した。歴史的長期間持続の黒潮大蛇行の長期化要因を明らかにした。高い再現性を有するデータ同化モデルを用いることで、これまで再現が困難であった、異常潮位や急潮現象を再現し、そのメカニズムを明らかにした。