scholarly journals Physical Modulation to the Biological Productivity in the Summer Vietnam Upwelling System

2018 ◽  
Author(s):  
Wenfang Lu ◽  
Enhui Liao ◽  
Xiao-Hai Yan ◽  
Lie-Yauw Oey ◽  
Wei Zhuang ◽  
...  
Keyword(s):  
Kinetic Energy ◽  
South China Sea ◽  
Ocean Circulation ◽  
South China ◽  
Coastal Upwelling ◽  
Current System ◽  
Coupled Model ◽  
Biological Productivity ◽  
China Sea ◽  
Upwelling System

Abstract. Biological productivity in the summer Vietnam boundary upwelling system in the western South China Sea, as in many coastal upwelling systems, is strongly modulated by wind. However, the role of ocean circulation and mesoscale eddies has not been elucidated. Here we show a close spatio-temporal covariability between primary production and kinetic energy. High productivity is associated with high kinetic energy, which accounts for ~ 15 % of the production variability. Results from a physical-biological coupled model reveal that the elevated kinetic energy and intensified circulation can be explained by the separation of the upwelling current system. The separated current forms an eastward jet into the interior South China Sea, and the associated southern gyre traps nutrient and favors productivity. When separation is absent, the model shows weakened circulation and eddy activity, with ~ 21 % less nitrate inventory and ~ 16 % weaker primary productivity.

scholarly journals Physical modulation to the biological productivity in the summer Vietnam upwelling system

Ocean Science ◽  
2018 ◽  
Vol 14 (5) ◽  
pp. 1303-1320 ◽  
Author(s):  
Wenfang Lu ◽  
Lie-Yauw Oey ◽  
Enhui Liao ◽  
Wei Zhuang ◽  
Xiao-Hai Yan ◽  
...  
Keyword(s):  
Kinetic Energy ◽  
South China Sea ◽  
Ocean Circulation ◽  
South China ◽  
Coastal Upwelling ◽  
Coupled Model ◽  
Biological Productivity ◽  
High Productivity ◽  
China Sea ◽  
Upwelling System

Abstract. Biological productivity in the summer Vietnam boundary upwelling system in the western South China Sea, as in many coastal upwelling systems, is strongly modulated by wind. However, the role of ocean circulation and mesoscale eddies has not been elucidated. Here, we show a close spatiotemporal covariability between primary production and kinetic energy. High productivity is associated with high kinetic energy, which accounts for ∼15 % of the production variability. Results from a physical–biological coupled model reveal that the elevated kinetic energy is linked to the strength of the current separation from the coast. In the low production scenario, the circulation is not only weaker but also shows weak separation. In the higher production case, the separated current forms an eastward jet into the interior South China Sea, and the associated southern recirculation traps nutrients and favors productivity. When separation is absent, the model shows weakened circulation and eddy activity, with ∼21 % less nitrate inventory and ∼16 % weaker primary productivity.

scholarly journals Intensification of Downslope Nutrient Transport and Associated Biological Responses Over the Northeastern South China Sea During Wind-Driven Downwelling: A Modeling Study

2021 ◽  
Vol 8 ◽  
Author(s):  
Aiqin Han ◽  
Jianping Gan ◽  
Minhan Dai ◽  
Zhongming Lu ◽  
Linlin Liang ◽  
...  
Keyword(s):  
South China Sea ◽  
Water Column ◽  
South China ◽  
Coastal Upwelling ◽  
Nutrient Transport ◽  
Field Measurements ◽  
Time Lags ◽  
Biological Productivity ◽  
China Sea ◽  
Northeastern South China Sea

Coastal downwelling is generally considered to have a limited biological effect compared with coastal upwelling. In this study, downslope transport of nearshore, nutrient-enriched waters during downwelling is found to induce distinct biological productivity in the water column over the northeastern South China Sea (NSCS). By conducting a process-driven study over a widened shelf with intensified downwelling in the NSCS, we investigated the biophysical processes associated with strong nutrient enrichment in the water column of downwelled waters. These processes and underlying mechanisms are largely unreported and remain unclear. Field measurements and a three-dimensional coupled physical-biological model incorporating nitrate (N), phytoplankton (P), zooplankton (Z), and detritus (D) were utilized to investigate distinct cross-shore nutrient transport over the uniquely widened NSCS shelf. We revealed that intensified downwelling circulation, dynamically induced by the widened shelf topography, enhanced chlorophyll a and biological productivity in a strip of well-mixed water over the inner shelf as well as in the downwelled water over the mid-shelf. Strong time lags and spatial differences existed among N, P, and Z because of the physical transport and the ensuing biogeochemical response. The intensified downslope transport of nutrient-rich coastal water formed distinct cross-shore wedge-shaped P, Z, and D structures, while N was rapidly consumed in the water column. This study illustrates the underlying coupled physical-biogeochemical processes associated with the observed biogeochemical response to wind-driven downwelling circulation over the variable shelf, which are commonly found in coastal oceans worldwide.

scholarly journals Correlation of Near-Inertial Wind Stress in Typhoon and Typhoon-Induced Oceanic Near-Inertial Kinetic Energy in the Upper South China Sea

Atmosphere ◽  
2019 ◽  
Vol 10 (7) ◽  
pp. 388
Author(s):  
Li ◽  
Xu ◽  
Liu ◽  
He ◽  
Chen ◽  
...  
Keyword(s):  
Kinetic Energy ◽  
South China Sea ◽  
Wind Energy ◽  
Wind Stress ◽  
South China ◽  
Translation Speed ◽  
China Sea ◽  
Typhoon Track ◽  
Upper South ◽  
Inertial Currents

The correlation of near-inertial wind stress (NIWS) in typhoon and typhoon-induced oceanic near-inertial kinetic energy (NIKE) in the upper South China Sea (SCS) is investigated through reanalysis data and an idealized typhoon model. It is found that the typhoon-induced oceanic near-inertial currents are primarily induced by the NIWS, which may contribute to about 80% of the total NIKE induced by typhoon. The intensities and distributions of NIWS in most typhoons are consistent with the magnitudes and features of NIKE. The NIWS and the NIKE along the typhoon track have positive correlations with the maximum wind speed of a typhoon, but there is an optimal translation speed for NIWS, at which the wind energy of the near-inertial band reaches its maximum. In the idealized typhoon model, a cluster of high-value centers of NIWS appear along the typhoon track, but there is only one high-value center for the near-inertial currents. The maximum NIWS arrives about 15 hours prior to the maximum near-inertial current. The distribution of NIWS is apparently asymmetric along the typhoon track, which may be due to the smaller eastward component of wind energy.

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