Association between the Biophysical Environment in Coastal South China Sea and Large-Scale Synoptic Circulation Patterns: The Role of the Northwest Pacific Subtropical High and Typhoons

Synoptic weather conditions can modulate short-term variations in the marine biophysical environment. However, impact of large-scale synoptic circulation patterns (LSCPs) on chlorophyll-a (chl-a) and sea surface temperature (SST) South China Sea (SCS) remains unclear. Using a T-mode principal component analysis method, four types LSCP related to Northwest Pacific subtropical high are objectively identified over SCS for summers 2015–2018. Type 1 exhibits lower chl-a concentration <0.3 mg m?3 offshore southern Vietnam with respect other three types. For 2, zone (>0.3 m?3) along coast Guangdong widest areas coverage. The bloom jet formed is most obvious under 3. Under 4, narrowest, while middle lowest (<0.1 m?3). These type differences mostly caused by various monsoon circulations, local ocean mesoscale processes resultant localized precipitation, wind vectors, photosynthetically active radiation SST. In particular, precipitation land helps transport nutrients from shore, which conducive increase chl-a. will dilute upper seawater reduce Typhoons pump deeper surface, therefore make positive contribution areas; however, they also disturb shallower water hinder growth phytoplankton, making negative near Guangdong. general, our findings provide better understanding impact: responses environments LSCPs.