The Linkage of Kuroshio Intrusion and Mesoscale Eddy Variability in the Northern South China Sea: Subsurface Speed Maximum

Wang, Qiang; Zeng, Lili; Chen, Ju; He, Yuehui; Zhou, Weidong; Wang, Dongxiao

doi:10.1029/2020gl087034

Cited by 25 publications

(21 citation statements)

References 59 publications

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“…Because of the limited spatial and temporal coverage of the observations, we also use the 6 years output from the Hybrid Coordinate Ocean Model (HYCOM) + Navy Coupled Ocean Data Assimilation global 1/12° Analysis (GLBv0.08; Cummings & Smedstad, 2013), from 2013 to 2018, to examine the processes that lead to the observed deep‐flow variability. This data set covers a sufficiently long period to resolve the intraseasonal motions and has been validated to reproduce multiscale processes in the SCS (e.g., Shu et al., 2014; Sun et al., 2020; Wang, Zeng, Chen, et al., 2020). The 3‐h data set has a horizontal resolution of about 8.4–9.2 km at 5°–25°N and 41 vertical levels from 0 to 5,500 m (1,000, 1,250, 1,500, 2,000, 2,500, 3,000, 4,000, 5,000, and 5,500 m for the deep layer).…”

Section: Methodsmentioning

confidence: 99%

“…The Kuroshio intrusion into the NSCS is mainly confined to the upper 500 m (J. Tian et al., 2006; Q. Yang et al., 2010; Zhang et al., 2015) and usually occurs in three characteristic forms (Figure 2b; Nan et al., 2011a). The instability associated with the Kuroshio near the Luzon Strait can result in frequent mesoscale eddy shedding (Zhang et al., 2013, 2017), which has been suggested to contribute greatly to the eddy activity and intraseasonal variability of the upper‐layer flow in the NSCS (Chen et al., 2011; Wang, Zeng, Chen, et al., 2020; Wang, Zhou, et al., 2020; Xiu et al., 2010). In this study, we demonstrate that the Kuroshio intrusion and related eddies in the upper layer also contribute to the intraseasonal variability of the deep flow in the NSCS.…”

Section: Introductionmentioning

confidence: 99%

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Influence of the Kuroshio Intrusion on Deep Flow Intraseasonal Variability in the Northern South China Sea

et al. 2021

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Interactions between the open ocean and marginal seas have been suggested to be critical to the redistribution and dissipation of global energy. Here, we propose a mechanism for the upper open ocean influencing the deep flow in marginal seas that hinges on the formation and propagation of topographic Rossby waves (TRWs). Observations and high‐resolution simulations suggest substantial intraseasonal variability with periods of 5–60 days associated with the deep flow over continental slopes of the northern South China Sea (NSCS). These fluctuations generally account for over 40% of the total deep kinetic energy variability and the number can reach 70% over the slopes to the west of the Luzon Strait, southwest of the Dongsha Islands, and northeast of the Xisha Islands. By examining the spatiotemporal features of the fluctuations, we demonstrate that the intraseasonal variability of the deep flow in the NSCS is closely associated with TRWs. Using a recently developed multiscale energetics analysis in combination with a ray tracing model, we show that the energy sources of TRWs can be traced back to the east of the Dongsha Islands, where the Kuroshio intrusion and related eddies energize the TRWs primarily through pressure work. These waves propagate westward across the NSCS and drive the intraseasonal variability of the deep flow over continental slopes. Our findings highlight an energy pathway from the open ocean western boundary current to the abyssal marginal sea that could modulate regional circulation as well as exchanges between major ocean basins.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Influence of the Kuroshio Intrusion on Deep Flow Intraseasonal Variability in the Northern South China Sea

et al. 2021

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“…Due to the complex topography, orographic wind jets, variable wind stress curl pattern, and instability of the Kuroshio intrusion (Liu and Su, 1992;Li et al, 1998;Wang et al, 2000;Yang and Liu, 2003;Wang et al, 2020), mesoscale eddies are active in the northern South China Sea (SCS; Huang, 1992;Zhang, 1994;Su et al, 1999;Chen, 2010;Xiu et al, 2010;Chen et al, 2011;He et al, 2018).…”

Section: Introductionmentioning

confidence: 99%

How Much Heat and Salt Are Transported Into the South China Sea by Mesoscale Eddies?

2021

Self Cite

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Eddy-induced transport through the Luzon Strait critically affects the physical and biological properties of the South China Sea (SCS). The eddy-induced volume, heat and salt transport are comprehensively evaluated based on the South China Sea Physical Oceanic Dataset (SCSPOD) observations. To avoid the bias involved in extreme eddy events, 76 shedding anticyclonic eddies, 46 shedding cyclonic eddies, 29 locally formed anticyclonic eddies and 40 locally formed cyclonic eddies from 1993 to 2018 are taken into account and merged into composites. The total annual intrusions of volume, heat and salt contributed by all four types of eddies are 0.77 Sv, 8.78×10 -4 PW and 7.88×10 4 kg•s -1 , respectively. The statistical analysis shows that annual eddy-induced intrusion accounts for 11.3%~38.9% of the upper-layer Luzon Strait transport, which highlights the non-negligible role of eddies in water exchange through the Luzon Strait.

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“…For example, the eddy impinging on the Kuroshio may alter its axis, from a leaping path that flows directly northward across the LS to a penetrating path that loops toward the SCS (D. Yuan et al., 2019). This Kuroshio‐eddy interaction may induce an eddy‐shedding event, which offers a route for water exchange between the Kuroshio and the SCS (Z. Zhang et al., 2017) and impacts upper layer circulation in the SCS (Lin et al., 2016; Wang et al., 2019, 2020; Xu and Oey, 2014, 2015; Z. Zhang et al., 2013).…”

Section: Introductionmentioning

confidence: 99%

Variations of the Kuroshio in the Luzon Strait Revealed by EOF Analysis of Repeated XBT Data and Sea‐Level Anomalies

Zhu

Guo

et al. 2021

JGR Oceans

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The Kuroshio in the Luzon Strait (KLS) has long been a focus of research for its complex ocean dynamics; however, it is poorly understood owing to a lack of long‐term in situ observations. Empirical orthogonal function (EOF) analyses were applied to quarterly expendable bathythermograph data (XBT, with a spatial resolution of 10–20 km in the Kuroshio region and 33 km in the other regions) and sea‐level anomaly (SLA) data, to examine the variations of the KLS. The first EOF modes of water temperature and SLA represent seasonal variations. The volume transport of the KLS referring to a 700 m depth reaches its maximum in warm months (19.4 Sv, July–September) and its minimum in cold months (17 Sv, January–March). This variation is similar to that east of Taiwan but is opposite to that east of Luzon, although the Luzon Strait is only 2° distant from the area east of Luzon. The outflow (1.3 Sv) from the South China Sea (SCS) to the Kuroshio in the warm months and the Kuroshio intrusion into the SCS in the cold months are responsible for this seasonal contrast. The second EOF modes of water temperature and SLA are related to the latitudinal movement of the Kuroshio recirculation on a time scale of 2–24 months. Lag correlation and wavelet analysis demonstrate that this mode is triggered by the westward‐propagating SLA along 21°–24°N and is affected by the downstream propagation of low‐frequency variation (mostly annual to biennial) from the North Equatorial Current bifurcation area.

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The Linkage of Kuroshio Intrusion and Mesoscale Eddy Variability in the Northern South China Sea: Subsurface Speed Maximum

Cited by 25 publications

References 59 publications

Influence of the Kuroshio Intrusion on Deep Flow Intraseasonal Variability in the Northern South China Sea

Influence of the Kuroshio Intrusion on Deep Flow Intraseasonal Variability in the Northern South China Sea

How Much Heat and Salt Are Transported Into the South China Sea by Mesoscale Eddies?

Variations of the Kuroshio in the Luzon Strait Revealed by EOF Analysis of Repeated XBT Data and Sea‐Level Anomalies

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