Modeling long‐term change of planktonic ecosystems in the northern <scp>S</scp>outh <scp>C</scp>hina <scp>S</scp>ea and the upstream <scp>K</scp>uroshio <scp>C</scp>urrent

Li, Qian P.; Wang, Yanjun; Dong, Yuan; Gan, Jianping

doi:10.1002/2014jc010609

Cited by 30 publications

(41 citation statements)

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“…The vertical diffusion negatively influences the nitracline steepness. The modeled time series distributions of nitrate gradients and diffusive nitrate fluxes in the northern SCS and the upstream Kuroshio Current showed similar results (Li et al, 2015). Beckmann and Hense (2007) conducted a sensitivity analysis of both vertical diffusivity and nutrient concentration at the bottom boundary to examine the vertical phytoplankton and nutrient profiles in oligotrophic oceans, and their numerical results support the relations presented in Eq.…”

Section: Steepness Of the Nitraclinementioning

confidence: 52%

“…In some oligotrophic oceans, the SCML will be deeper than the SBML due to the effect of photoacclimation on the vertical distribution of chlorophyll (Fennel and Boss, 2003). For example, Li et al (2015) showed that the modeled maximum nitrate gradient (nitracline) occurred below the depth of the SCML in the northern SCS, and then we can deduce that the nitracline depth is also deeper than the depth of the SBML. In the Mediterranean Sea, Bahamón et al (2003) found that the nitracline occurred below the depth of the SCML at 88 % of the stations (50 out of 57 stations).…”

Section: Data Sourcesmentioning

confidence: 94%

“…We assume that surface diffusivity (K v1 ) and subsurface diffusivity (K v2 ) (Lande and Wood, 1987;Hodges and Rudnick, 2004) are constant and K v1 is large enough to homogenize the chlorophyll and nitrogen Li et al (2015).…”

Section: Dynamic Equationsmentioning

confidence: 99%

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Analytical solution of the nitracline with the evolution of subsurface chlorophyll maximum in stratified water columns

et al. 2017

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Abstract. In a stratified water column, the nitracline is a layer where the nitrate concentration increases below the nutrient-depleted upper layer, exhibiting a strong vertical gradient in the euphotic zone. The subsurface chlorophyll maximum layer (SCML) forms near the bottom of the euphotic zone, acting as a trap to diminish the upward nutrient supply. Depth and steepness of the nitracline are important measurable parameters related to the vertical transport of nitrate into the euphotic zone. The correlation between the SCML and the nitracline has been widely reported in the literature, but the analytic solution for the relationship between them is not well established. By incorporating a piecewise function for the approximate Gaussian vertical profile of chlorophyll, we derive analytical solutions of a specified nutrient-phytoplankton model. The model is well suited to explain basic dependencies between a nitracline and an SCML. The analytical solution shows that the nitracline depth is deeper than the depth of the SCML, shoaling with an increase in the light attenuation coefficient and with a decrease in surface light intensity. The inverse proportional relationship between the light level at the nitracline depth and the maximum rate of new primary production is derived. Analytic solutions also show that a thinner SCML corresponds to a steeper nitracline. The nitracline steepness is positively related to the light attenuation coefficient but independent of surface light intensity. The derived equations of the nitracline in relation to the SCML provide further insight into the important role of the nitracline in marine pelagic ecosystems.

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Section: Steepness Of the Nitraclinementioning

confidence: 52%

Section: Data Sourcesmentioning

confidence: 94%

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Analytical solution of the nitracline with the evolution of subsurface chlorophyll maximum in stratified water columns

et al. 2017

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“…Here we study the temporal variability of export production (EP) at a pelagic station of XS (Figure ) with a 1‐D physical‐biogeochemical coupling model (Li et al, ). We evaluate the model results by comparing them with the time series data of XS, including the satellite sea surface temperature (SST) and sea surface chlorophyll‐ a (SSChla) from January 2000 to December 2014, the IPP from January 2005 to December 2014, and the sinking POC flux by a moored sediment‐trap from August 2012 to September 2014.…”

Section: Introductionmentioning

confidence: 99%

Temporal Change of Export Production at Xisha of the Northern South China Sea

Chen

2018

JGR Oceans

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Physical‐biological interaction within the upper ocean influences fixed organic carbon with various efficiencies leading to spatial and temporal change of carbon export in the ocean, which is important for global biogeochemical dynamics but is inadequately understood in the northern South China Sea (NSCS). Here the temporal variations of primary and export production are investigated using a 1‐D physical‐biogeochemical coupling model at a pelagic station of Xisha (XS) in the NSCS. At this station, the model reproduces the satellite sea surface observations, the depth‐integrated primary production, and the sinking flux of particulate organic carbon at 500 m from a moored sediment trap. By synthesizing these results, we investigate the long‐term dynamics of the biological pump with the focus on export production. We compared our results at XS with that at A Long‐Term Oligotrophic Habitat Assessment (ALOHA) in the North Pacific subtropical gyre. While the surface export at XS is greater than ALOHA, the stronger subsurface remineralization at XS has resulted in a similar week biological pump as ALOHA. The high surface export and subsurface flux attenuation at XS are caused by its physical dynamics that support a stronger upward nitrate flux than ALOHA. We also find a time lag of about 20 days between primary production and export production at XS, which has led to the large variability of export ratios in the subsurface layers. Further analyses suggest that the temporal variations of primary and export productions are largely driven by the change of turbulent mixing and Ekman pumping that control the vertical nutrient fluxes into the upper ocean.

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“…(Tian et al, 2009;Liu and Lozovatsky, 2012;Yang et al, 2014). It was also suggested that phytoplankton blooms off the west coast of the nSCS could be induced by wind stress curl-driven upwelling during the spring inter-monsoon season (Wang and Tang, 2014), which would cause a local uplift of isopycnals leading to nutrient injection into the euphotic zone with subsequent changes of community structure and productivity (Rykaczewski and Checkley, 2008;Li et al, 2015). By modifying the surface wind stress and wind stress curl via air-sea coupling, the eddy-induced Ekman pumping (Gaube et al, 2013) was important for phytoplankton production in the nSCS during the inter-monsoon transition period (Lin et al, 2010).…”

Section: Introductionmentioning

confidence: 99%

Phytoplankton dynamics driven by vertical nutrient fluxes during the spring inter-monsoon period in the northeastern South China Sea

Dong

Wang

2016

Biogeosciences

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Abstract.A field survey from the coastal ocean zones to the offshore pelagic zones of the northeastern South China Sea (nSCS) was conducted during the inter-monsoon period of May 2014 when the region was characterized by prevailing low-nutrient conditions. Comprehensive field measurements were made for not only hydrographic and biogeochemical properties but also phytoplankton growth and microzooplankton grazing rates. We also performed estimations of the vertical turbulent diffusivity and diffusive nutrient fluxes using a Thorpe-scale method and the upwelling nutrient fluxes by Ekman pumping using satellite-derived wind stress curl. Our results indicated a positive correlation between the integrated phytoplankton chlorophyll a and vertical nutrient fluxes in the offshore region of the nSCS during the study period. We generally found an increasing role of turbulent diffusion but a decreasing role of curl-driven upwelling in vertical transport of nutrients from the coastal ocean zones to the offshore pelagic zones. Elevated nutrient fluxes near Dongsha Islands supported high new production leading to net growth of the phytoplankton community, whereas the low fluxes near the southwest of Taiwan had resulted in a negative net community growth leading to decline of a surface phytoplankton bloom. Overall, phytoplankton dynamics in the large part of the nSCS could be largely driven by vertical nutrient fluxes including turbulent diffusion and curl-driven upwelling during the spring inter-monsoon period.

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Modeling long‐term change of planktonic ecosystems in the northern South China Sea and the upstream Kuroshio Current

Cited by 30 publications

References 50 publications

Analytical solution of the nitracline with the evolution of subsurface chlorophyll maximum in stratified water columns

Analytical solution of the nitracline with the evolution of subsurface chlorophyll maximum in stratified water columns

Temporal Change of Export Production at Xisha of the Northern South China Sea

Phytoplankton dynamics driven by vertical nutrient fluxes during the spring inter-monsoon period in the northeastern South China Sea

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