Development of upwelling on pathway and freshwater transport of <scp>P</scp>earl <scp>R</scp>iver plume in northeastern <scp>S</scp>outh <scp>C</scp>hina <scp>S</scp>ea

Chen, Zhaoyun; Jiang, Yuwu; Liu, James T.

doi:10.1002/2016jc012411

Cited by 20 publications

(16 citation statements)

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“…The summer southwesterly wind is widely regarded as the main driving mechanism for coastal upwelling in the NSCS according to the classical Ekman theory (Gu et al, ; Hu et al, ; Hu & Wang, ; Li, ; Shaw, ; Su, ). The spatial distribution of the NSCS coastal upwelling intensity is controlled by the orientation of the monsoon winds and the wide shelf topography (Chen et al, , ; Gan et al, ; Su & Pohlmann, ). Gan et al () found that the cold, dense bottom water advecting from outer Shanwei outcrops near the shore of Shantou because of the alongshore gradient force induced by the alongshore topography and coastal line.…”

Section: Introductionmentioning

confidence: 99%

The Contribution of Local Wind and Ocean Circulation to the Interannual Variability in Coastal Upwelling Intensity in the Northern South China Sea

Shu

Wang

Feng³

et al. 2018

JGR Oceans

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Using in situ data, satellite observations, and model outputs, we analyzed the interannual variability in coastal upwelling intensity in the northern South China Sea. Comparing coastal upwelling observed from three cruises during the summers of 2008 and 2016, we found that coastal upwelling was stronger during 2016 compared to 2008, although the local upwelling favorable wind was stronger in 2008. The stronger near-bottom cross-shelf current and shallower thermocline in the slope resulted in stronger upwelling intensity during the summer of 2016. The topographic position index (TPI), which is defined by the sea surface temperature difference between one center cell and its neighbors, was used to quantify the interannual variability in upwelling. Stronger (weaker) upwelling intensity occurred during the summers of ) when the local wind was more favorable (less favorable) to coastal upwelling. The correlation coefficient between the area-weighted TPI and alongshore wind speed was À0.60, thereby confirming that local wind is the primary dynamical factor controlling the interannual variability in upwelling intensity. The correlation coefficient between the area-weighted TPI and the eastward boundary current transport averaged between the 75-and 100-m isobaths on the shelf was À0.42, indicating that the interannual variability in large-scale circulation in the northern South China Sea also contributes to the interannual variability in upwelling intensity. The anomalously shallow thermocline in the summer of 2016 was likely associated with the strong 2015-2016 El Niño event through planetary wave propagations.Plain Language Summary Coastal upwelling, transporting deep, cold, saline, and nutrient-rich water to the surface result in high levels of primary production and fishery production. The coast of the northern South China Sea (NSCS) features seasonal coastal upwelling during the boreal summer. The summer southwesterly wind is widely regarded as the main driving mechanism for coastal upwelling in the NSCS. Previous studies have shown that the interannual variability in coastal upwelling intensity is largely controlled by the interannual variability in local winds in the NSCS, which is closely related to the El Niño-Southern Oscillation. Based on in situ data, we found that the upwelling was much stronger during 2016 than during 2008, though the local wind was more favorable to upwelling during 2008, which indicated that local wind is not the sole factor controlling the interannual variability in upwelling intensity in the NSCS. Further studies showed that, beside the locale wind, the interannual variability in shelf circulation could also contribute to the interannual variability in coastal upwelling intensity due to the topographically induced upwelling (induced by the interaction between northeastward large-scale current and alongshore variable topography) in the NSCS. In addition, thermocline depth variation on interannual time scale likely influences the coastal upwelling intensity in the NSCS.

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Section: Introductionmentioning

confidence: 99%

The Contribution of Local Wind and Ocean Circulation to the Interannual Variability in Coastal Upwelling Intensity in the Northern South China Sea

Shu

Wang

Feng³

et al. 2018

JGR Oceans

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“…2 , Supplementary Fig. 5 ), this mode demonstrates the cold-water intrusion related to the wind, which leads to upwelling near the coast 37 , 42 , 43 . The contour plot of eigenweightings indicates the thickening of the cold water in the lower column that gradually extended upward into shallower depths (the red patch in Fig.…”

Section: Discussionmentioning

confidence: 94%

“…After exiting the funnel-shaped Pearl River Estuary (PRE), the terrestrial effluent affected the characteristics and biogeochemistry of water masses along the pathway of the plume 36 . The northeastward dispersal of the Pear River plume largely depends on the wind field and coastal currents 37 , 42 , 43 . Under the prevailing upwelling-favorable monsoon winds, the buoyant river plume is trapped and propagating northeastward further along the upwelling front because of the strong cross-shore temperature gradient.…”

Section: Introductionmentioning

confidence: 99%

“…Although the plume dynamics and circulation systems in this region have been well documented 37 , 38 , 41 , 43 , most studies are based on model simulations as well as spatial observation along transects. This might cause the time and space aliasing issues from the observations and, consequently, lose the temporal variability of the water-mass signatures under the plume-ambient water interaction on the river plume pathway.…”

Section: Introductionmentioning

confidence: 99%

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Encountering shoaling internal waves on the dispersal pathway of the pearl river plume in summer

Lee

Liu

Lee

et al. 2021

Sci Rep

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Fundamentally, river plume dynamics are controlled by the buoyancy due to river effluent and mixing induced by local forcing such as winds and tides. Rarely the influence of far-field internal waves on the river plume dynamics is documented. Our 5-day fix-point measurements and underway acoustic profiling identified hydrodynamic processes on the dispersal pathway of the Pearl River plume. The river plume dispersal was driven by the SW monsoon winds that induced the intrusion of cold water near the bottom. The river effluent occupied the surface water, creating strong stratification and showing on-offshore variability due to tidal fluctuations. However, intermittent disruptions weakened stratification due to wind mixing and perturbations by nonlinear internal waves (NIWs) from the northern South China Sea (NSCS). During events of NIW encounter, significant drawdowns of the river plume up to 20 m occurred. The EOF deciphers and ranks the contributions of abovementioned processes: (1) the stratification/mixing coupled by wind-driven plume water and NIWs disruptions (81.7%); (2) the variation caused by tidal modulation (6.9%); and (3) the cold water intrusion induced by summer monsoon winds (5.1%). Our findings further improve the understanding of the Pearl River plume dynamics influenced by the NIWs from the NSCS.

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“…Due to a lack of sufficient observations, detection and analysis of the intraseasonal signal in the river plume are difficult. Remote sensing offers a unique method to study the sea surface salinity (SSS) associated with various oceanic and climatological phenomena [28][29][30]. Launched in January 2015, NASA's Soil Moisture Active Passive (SMAP) platform and mission provide unique and complementary observations to study floods and discharged freshwater in coastal estuarine regions [31,32].…”

Section: Madden-julian Oscillation-related Offshore Transport Of the mentioning

confidence: 99%

High-Frequency Variations in Pearl River Plume Observed by Soil Moisture Active Passive Sea Surface Salinity

Liao

Wang

et al. 2020

Remote Sensing

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River plumes play an important role in the cross-margin transport of phytoplankton and nutrients, which have profound impacts on coastal ecosystems. Using recently available Soil Moisture Active Passive (SMAP) sea surface salinity (SSS) data and high-resolution ocean color products, this study investigated summertime high-frequency variations in the Pearl River plume of China and its biological response. The SMAP SSS captures the intraseasonal oscillations in the offshore transport of the Pearl River plume well, which has distinct 30–60 day variations from mid-May to late September. The offshore transport of freshwater varies concurrently with southwesterly wind anomalies and is roughly in phase with the Madden–Julian Oscillation (MJO) index in phases 1–5, thus implying that the MJO exerts a significant influence. During MJO phases 1–2, the southwest wind anomalies in the northeastern South China Sea (SCS) enhanced cross-shore Ekman transport, while the northeast wind anomalies during MJO phases 3–5 favored the subsequent southwestward transport of the plume. The high chlorophyll-a concentration coincided well with the low-salinity water variations, emphasizing the important role of the offshore transport of the Pearl River plume in sustaining biological production over the oligotrophic northern SCS. The strong offshore transport of the plume in June 2015 clearly revealed that the proximity of a cyclonic eddy plays a role in the plume’s dispersal pathway. In addition, heavy rainfall related to the landfall of tropical cyclones in the Pearl River Estuary region contributed to the episodic offshore transport of the plume.

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Development of upwelling on pathway and freshwater transport of Pearl River plume in northeastern South China Sea

Cited by 20 publications

References 44 publications

The Contribution of Local Wind and Ocean Circulation to the Interannual Variability in Coastal Upwelling Intensity in the Northern South China Sea

The Contribution of Local Wind and Ocean Circulation to the Interannual Variability in Coastal Upwelling Intensity in the Northern South China Sea

Encountering shoaling internal waves on the dispersal pathway of the pearl river plume in summer

High-Frequency Variations in Pearl River Plume Observed by Soil Moisture Active Passive Sea Surface Salinity

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