Typhoon Effects on the Vertical Chlorophyll Distribution on the Northern Shelf of the South China Sea

Abstract

Typhoons are known to induce strong ocean mixing and upwelling, bringing cold and nutrient-rich subsurface water to the surface layer. Cold subsurface water can generally lead to a decrease in sea surface temperature (SST) to the right of the typhoon track (Dickey et al., 1998;Price, 1981). The nutrient-rich subsurface water that is injected into the upper layer can stimulate phytoplankton growth and increase primary production (e.g., Babin et al., 2004;Lin et al., 2003;Walker et al., 2005). Reduced turbulence due to typhoon-induced submesoscale processes and rainfall has also been suggested to be able to induce phytoplankton blooms in the open ocean (Huang & Oey, 2015;Lin & Oey, 2016).Typhoons occur frequently in the South China Sea (SCS), with approximately 14 occurrences per year (Lin et al., 2003). In stratified seasons, phytoplankton growth in the upper layer of the SCS is generally limited due to low nutrient conditions in the open ocean (Chen et al., 2004). The passage of typhoons and the associated mixing and upwelling are thus important to the primary production and biogeochemical cycles of the SCS (G.

Impact of typhoons on the ecological environment of the Pearl River Estuary in the summer of 2021—a study of an algal bloom event

“…The northeast current, influenced by the summer southwest monsoon, causes the flow of the PRP toward the northeast of the estuary (Gan et al, 2010), and the passage of typhoons disrupts the flow dynamics, resulting in an amplified impact of the PRP on the western side of the estuary (Supplementary Figure S3). These findings highlight the dominance of the advection process driven by typhoons in the occurrence of algal blooms, which dissipate as the flow field changes (Zhao et al, 2009;Fang et al, 2022;Feng et al, 2022). However, unlike the findings from previous studies, the temporal fluctuations in the Chla and NO3 concentrations appeared nearly synchronous, emphasizing direct Chla transport rather than a process of nutrientinduced phytoplankton growth.…”

“…The CoSiNE model was initially developed to simulate marine geochemical processes in the equatorial Pacific Ocean (Chai et al, 2002) and has been applied at various spatial scales, including the North Pacific Ocean (Xiu and Chai, 2012), SCS (Pan et al, 2017) and PRE (Fang et al, 2022). Additionally, the model has been applied to study the responses of marine ecosystems to typhoon events (Pan et al, 2017;Fang et al, 2022). The parameter settings of the biogeochemical model for this study can be found in Table 1.…”

“…This runoff carries substantial amounts of nutrients, resulting in notable ecological features in the Pearl River estuary (PRE), such as eutrophication, algal blooms, and hypoxia (Harrison et al, 2008;Lai and Yin, 2014;Lu and Gan, 2015). Furthermore, the PRE is frequently impacted by typhoons with an average of about 3 typhoons passing through the PRE each year, which cause changes in the extent of the Pearl River plume (PRP) because of the change of flow field caused by wind field and the increase of Pearl River discharge (Wang and Zhang, 2021;Fang et al, 2022;Feng et al, 2022). These interactions between typhoons and the Pearl River runoff have obvious implications for the marine ecosystem in the region.…”

“…Numerical simulations using biogeochemical models have been an effective method for studying the responses of oceans to typhoons, especially under extreme weather conditions (Pan et al, 2017;Zhang et al, 2021), and it provide continuous time series and large-scale data for comprehensive analysis. These simulations have shown that phytoplankton growth in nearshore areas is influenced by various factors, including mixing and nutrient input (Fang et al, 2022;Feng et al, 2022;Li et al, 2022). In addition, the impacts on upwelling and plumes vary under different typhoon trajectories or intensities (Pan et al, 2012;Chen et al, 2023), and the factors that contribute to coastal algae blooms also differ, such as typhoon wind pumps and transportation of terrestrial material by precipitation, with algal blooms primarily dependent on nutrient supply (Liu et al, 2021;Chen et al, 2023;Lao et al, 2023b, Lao et al, 2023cChen et al, 2024).…”

The Investigation of the Response Mechanism of SST and Chlorophyll to Super Typhoon “Rey” in the South China Sea

“…The concentration of Chl-a near the shore is influenced by monsoon patterns, upwelling events, and the influx of coastal rivers. Consequently, a pronounced increase in Chl-a concentration occurs in proximity to the shoreline, whereas variations in daily sea surface wind speed far from the coast do not significantly impact Chl-a levels [30,31]. Before the typhoon, the average concentration of Chl-a in the South China Sea study area was 0.37 mg/L (Table 4).…”