Topographic Beta Spiral and Onshore Intrusion of the Kuroshio Current

Yang, Dezhou; Huang, Rui Xin; Yin, Baoshu; Feng, Xingru; Chen, Haiying; Qi, Jia; Xu, Lingjing; Shi, Yunfeng; Cui, Xuan; Gao, Guandong; Benthuysen, Jessica A.

doi:10.1002/2017gl076614

Cited by 44 publications

(37 citation statements)

References 24 publications

(38 reference statements)

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“…It causes the upper KSSW left‐hand spiral, dragging the deeper KSSW upwelling and intruding into ECS shelf. These results demonstrate the theory of topographic beta spiral by Yang et al (), explaining why the colder, oxygen‐poorer, and nutrient‐richer water from deeper layer can be observed on the continental shelf.…”

Section: Discussionsupporting

confidence: 87%

Intrusion Pattern of the Offshore Kuroshio Branch Current and Its Effects on Nutrient Contributions in the East China Sea

Wang

Song

et al. 2018

JGR Oceans

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During the autumn season of 2014 (October–November), nutrient samples and nitrogen and oxygen isotope samples from the East China Sea (ECS) were collected and analyzed, and auxiliary physical parameters were determined. Distinctive high‐salinity water column conditions with significant haloclines and pycnoclines similar to those observed during the spring were detected at the bottom of the ECS during the autumn. These water column conditions were attributed to the intrusion of the Kuroshio Subsurface Water (KSSW), which then separated into two currents, including the Offshore Kuroshio Branch Current (OKBC). Compared with spring, this intrusion transported higher phosphorus (P) concentrations onto the ECS continental shelf in autumn. However, according to multiple analyses, biogeochemical nitrogen processes are unable to explain the variations in the P concentrations (increase) while assuming that each distinctive water column is consistent. Identifying the water columns by their salinities and P concentrations revealed that the northern ECS water column was similar to the deep KSSW while the southern ECS water column was similar to the shallow KSSW. Therefore, we speculate that the distinctions among the seasonal variations of P‐enriched water masses were attributable to the different intrusion positions of the Kuroshio. The shift of the KSSW intrusion location moved toward the northeast during the autumn relative to the spring. This shift, which was proved by the oceanic vortex data, caused the deeper KSSW water upwelled to the ECS and formed the OKBC, thereby supplying additional P during the autumn.

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Section: Discussionsupporting

confidence: 87%

Intrusion Pattern of the Offshore Kuroshio Branch Current and Its Effects on Nutrient Contributions in the East China Sea

Wang

Song

et al. 2018

JGR Oceans

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“…Northeast of Taiwan, the surface Kuroshio intrusion current returns to the main stream of the Kuroshio Current, while the KSSW can be transported into the near-shore region off the Zhejiang Province by a submarine nearshore Kuroshio branch current that flows along the bottom of the ECS continental shelf. After reaching the submarine cannon off the Changjiang River mouth and Zhejiang coastal area, the Kuroshio branch current upwells as a result of favorable summer winds bringing subsurface water into the euphotic layer (Xu et al, 2018;Yang et al, 2012Yang et al, , 2018. From examination of the model experiment where nutrient input from the Kuroshio Current was removed (experiment KC = 0), the Kuroshio Current appears to be associated with maintaining levels of all three nutrients in the subsurface shelf water and PO 4 levels in the surface water (Figures 12c, 12f, and 12l).…”

Section: 1029/2020jg005727mentioning

confidence: 99%

Riverine and Oceanic Nutrients Govern Different Algal Bloom Domain Near the Changjiang Estuary in Summer

Yang

Greenwood

et al. 2020

JGR Biogeosciences

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The Changjiang Estuary and adjacent sea area in the East China Sea suffer from frequent harmful algal blooms. However, the relative importance of riverine nutrient input from the Changjiang River and oceanic nutrient input from the Taiwan Warm Current and Kuroshio Current to the development and distribution of summer phytoplankton blooms in this area remains unclear. To address this problem, we deployed a coupled physical-biological model. The coupled model successfully reproduces the main hydrographic and biogeochemical features in this domain. Both satellite observations and model results show two regions of elevated chlorophyll concentrated in this site. Simulated results show that harmful algal blooms in the region north of the Zhoushan Islands are mainly driven by riverine nutrients from the Changjiang River, while algal blooms in the region south of the Zhoushan Islands are mainly controlled by nutrients from the open ocean. Nutrient input, particularly phosphate, from the Kuroshio subsurface water contributes most to the accumulation of dinoflagellate biomass and chlorophyll in the southern region, while the Taiwan Warm Current has less influence. This has implications for nutrient control and land management practices: Although reducing riverine nutrient loads may significantly reduce phytoplankton growth north of the Zhoushan Islands, it will have little effect in the area to the south. Plain Language Summary Blooms of microscopic algae that can be harmful to marine ecosystems and commercial fisheries are increasingly common during the summer months in the Changjiang Estuary and adjacent sea area in the East China Sea. The Changjiang River is traditionally considered as the dominant source of nutrients driving these harmful algal blooms. In this study, we show that although this appears to be true for algal blooms occurring to the north and northeast of the river estuary, algal blooms that occur along the coast to the south of the river estuary are mainly regulated by nutrient input from the open ocean. Intrusion of the Kuroshio subsurface water to the south of the Changjiang Estuary is shown to be particularly important in supplying the dissolved phosphate necessary for the algae in the southern region to bloom in large quantities.

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“…A cyclonic eddy-like velocity anomaly takes place northeast of Taiwan, and the shoreward transport decreases, which gives decreased chlorophyll around the Zhoushan Islands and Yangtze Estuary. Meanwhile, we can also find that the increased inflow from the Taiwan Warm Current take place and supplies some phosphate along the Fujian coasts (Yang et al, 2018a). This can explain that the chlorophyll in the north of Taiwan is not obviously decreased in Figure 12(b).…”

Section: Possible Mechanism For Mic Kipt Influence On Ecs Chlorophyllmentioning

confidence: 84%

Boundary Phosphate Transport of the East China Sea and Its Influence on Biological Process

Lin¹,

Wang²,

Xiu³

et al. 2019

GEP

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The East China Sea (ECS) is one of the largest marginal seas in the Northwest Pacific, and also one of the most productive regions of the global ocean. Using a three-dimensional Pacific physical-biological model, we investigate the interannual variation of phosphate transport via Kuroshio intrusion (KIPT) in the eastern boundary of the East China Sea (ECS) and its influence on the ECS biological process during 1997 to 2016. The KIPT into the ECS mainly occurs in the northeast of Taiwan and southwest of Kyushu, with stronger interannual variability in the northeast of Taiwan. The variation of the KIPT is more significant in the near-bottom water, and is dominated by volume transport. On the interannual timescale, the KIPT changes in response to the shift of the Kuroshio axis and to the bottom upwelling in the ECS eastern boundary. When the Kuroshio axis is closer to (farther away from) the ECS shelf, the strength of the bottom upwelling increases (decreases). This process induces more (less) significant topographic beta spiral, which causes an anticyclonic (cyclonic) eddy-like bottom velocity feature in the northeast of Taiwan. Eventually, more phosphate is transported to the ECS inner shelf, which increases chlorophyll concentration around the Zhoushan Islands and Yangtze Estuary but reduces chlorophyll concentration in the ECS outer shelf. Conversely, the chlorophyll increases in the ECS outer shelf but decreases around the Zhoushan Islands and Yangtze Estuary when there is less phosphate transport. This study highlights the importance of Kuroshio intrusion in connecting the inner and outer shelves of the ECS on the interannual timescale. Phosphate transport into the East China Sea via Kuroshio intrusion shows

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Topographic Beta Spiral and Onshore Intrusion of the Kuroshio Current

Cited by 44 publications

References 24 publications

Intrusion Pattern of the Offshore Kuroshio Branch Current and Its Effects on Nutrient Contributions in the East China Sea

Intrusion Pattern of the Offshore Kuroshio Branch Current and Its Effects on Nutrient Contributions in the East China Sea

Riverine and Oceanic Nutrients Govern Different Algal Bloom Domain Near the Changjiang Estuary in Summer

Boundary Phosphate Transport of the East China Sea and Its Influence on Biological Process

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