Characteristics of the summer-autumn Kuroshio intrusion into the South China Sea induced by cyclonic mesoscale eddies

Fan Chengyang; Sun Zhongbin; Xu Zhouqing; Xie Meijie; Shang Gong; Zhang Zhiwei

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Fan Chengyang，Sun Zhongbin，Xu Zhouqing, et al. Characteristics of the summer-autumn Kuroshio intrusion into the South China Sea induced by cyclonic mesoscale eddies[J]. Haiyang Xuebao，2025, 47(x)：1–14

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Characteristics of the summer-autumn Kuroshio intrusion into the South China Sea induced by cyclonic mesoscale eddies

Fan Chengyang^1
,,
Sun Zhongbin^{1, 2, 3},
Xu Zhouqing¹,
Xie Meijie¹,
Shang Gong¹,
Zhang Zhiwei^{1, 2, 3
,
,}

1.
Key Laboratory of Physical Oceanography/College of Oceanic and Atmospheric Sciences, Ocean University of China, Qingdao 266100, China
2.
Key Laboratory of Ocean Observation and Information of Hainan Province, Sanya Oceanographic Institution, Ocean University of China, Sanya 572024, China
3.
Sanya Oceanographic Laboratory, Sanya 572024, China

Received Date: 2024-09-18
Rev Recd Date: 2025-02-18

Available Online: 2025-04-11

Abstract

Abstract

The intrusion of the Kuroshio into the South China Sea (SCS) has important effects on its circulation, thermohaline balance, mesoscale eddies and local climate. Kuroshio intrusion into the SCS predominantly occurs in winter and is relatively weaker during the summer-autumn (May–October). However, an analysis of observational data in the northeastern SCS in 2023 reveals that cyclonic mesoscale eddies on the western side of the Luzon Strait can significantly enhance summer-autumn Kuroshio intrusion into the SCS. The maximum observed salinity in the northeastern SCS reached 34.80. Further analysis integrating satellite altimetry and reanalysis data confirms that cyclonic eddies can induce Kuroshio intrusion into the SCS during the summer-autumn. The advection of the cyclonic eddies transported 3.05×10¹³ m³ of Kuroshio water into the SCS. A statistical analysis further identifies 25 occurrences of cyclonic eddy-induced Kuroshio intrusion into the SCS from 1993 and 2023. Over the 31 years, the additional summer-autumn water flux induced by cyclonic eddies has reached approximately 0.29 Sv, accounting for 8.1% of the total upper-layer flux in the Luzon Strait during summer and autumn. The north-south velocity asymmetry of cyclonic eddies is likely the primary mechanism enhancing Kuroshio intrusion into the SCS. These findings highlight the significant role of cyclonic eddy-induced Kuroshio intrusion during summer and autumn in facilitating water exchange between the SCS and the Northwest Pacific.
- cyclonic mesoscale eddies,
- Kuroshio invades South China Sea,
- summer-autumn,
- water flux

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References(48)

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