[A-OS19] Marine ecosystems and biogeochemical cycles: theory, observation and modeling

[AOS19-P06] Spatial and temporal variability of biological carbon pump in the northern South China Sea

*Jia-Jang Hung¹, Zong-Ying Lin, Ching-Han Tung, Shao-Hung Peng, Yen-Hui Lin (1.Department of Oceanography, National Sun Yat Sen University, Kaohsiung, Taiwan)

Keywords:Biological carbon pump, Spatial and temporal variability, Northern South China Sea

The marine biological carbon pump (BCP) consists mainly of active and passive fluxes, which transfers organic carbon produced in the euphotic zone to the deep ocean, may be critical in controlling the air-sea flux of atmospheric CO₂. Here we report the spatial and temporal variability of BCP in the northern South China Sea (NSCS) through a moderately long period of investigation including an observation in the time-series station (SEATS). The spatial variability of BCP was large in the NSCS, ranging from 25.6 mg C m^-2 d^-1 to 93.4 mg C m^-2 d^-1 for active fluxes and from 66.8 mg C m^-2 d^-1 to 155 mg C m^-2 d^-1 for passive fluxes. Vertical diffusion flux of DOC was very small compared to both active and passive fluxes. The magnitude of flux was generally lower in the central basin with a calm weather condition and higher in the Dongsha shelf influenced by the shoaling processes of internal waves. Both active and passive fluxes were apparently determined by the inventories of nutrients and chlorophyll a in the euphotic zone. In terms of temporal variability of BCP in the SEATS Station, the difference of BCP magnitude was significant between summer and winter seasons but less in inter-annual variability. The internal forcing and climatic conditions are likely critical factors in driving the spatial and temporal variability of BCP in the NSCS.