Winter phytoplankton bloom induced by subsurface upwelling and mixed layer entrainment southwest of Luzon Strait

Enhanced Chlorophyll Concentrations Induced by Kuroshio Intrusion Fronts in the Northern South China Sea

“…The LZB water in winter is close to the SCS water, while the water to the north is close to the Kuroshio water (Figure 2), dictated by Kuroshio intrusion paths in winter (Caruso et al, 2006;Nan et al, 2011Nan et al, , 2015. Unlike the previous work mainly focusing on the effects of mesoscale and large-scale processes (e.g., Chen et al, 2007;Lu et al, 2015;Wang et al, 2010), our results illustrate that the enhanced productivity in the LZB region is associated with the fronts induced by Kuroshio intrusion in winter and particularly frontal upwelling, which provides new insights into the impact of Kuroshio on the SCS ecosystem. The mechanism for generating upwelling in the frontal region can be explained by frontogenesis (Figure 4) such that the interaction between surface currents can enhance shear and straining, which sharpens the preexisting horizontal density gradient.…”

“…These high chlorophyll patches vary in 1-10 km distance in space and on daily basis in time, which is consistent with frontal features (Figure 1). Several mechanisms have been proposed to investigate the LZB dynamics, such as the monsoon-driven coastal upwelling (Qiu et al, 2012;Wang et al, 2010), the winter mixing (Lu et al, 2015), mesoscale eddies (Chen et al, 2007), remote advection from the coast (Liu et al, 2002;Lu et al, 2015), and upwelling caused by currents, such as the Luzon costal current (LCC) (Chen et al, 2006;Hu et al, 2000;Shaw et al, 1996). However, these studies mainly focused on the effects of large and mesoscale processes based on observations and model outputs with resolutions too coarse to resolve patchy phytoplankton dynamics and actually missed the underlying mechanisms for the occurrence of the extremely high chlorophyll.…”

Progress on upwelling studies in the China seas

“…J . Wang et al ., 2010; Zhao et al ., ]. In the Luzon Strait, the winter bloom occurs during the relaxation period of intensified northeasterly winds when the deepened mixed layer starts to shoal, and the advection of relative vorticity primarily contributes to the subsurface upwelling that supplies nutrients to the region below the mixed layer [ Lu et al ., ].…”

Seasonal variability of surface phytoplankton in the Northern South China Sea: A one-dimensional coupled physical-biogeochemical modeling study

“…coastal upwelling, basin scale to mesoscale eddies) primarily forced under the monsoon winds. Tang et al (1999) and Wang et al (2010) investigated the winter phytoplankton bloom phenomena occurred off the southwest of Luzon Strait in winter using both satellite derived data and shipboard measurements. They suggested that the phytoplankton bloom was mainly attributed to the winter upwelling occurring there (Shaw and Chao, 1994;Shaw et al, 1996).…”