Primary Research Of Air-sea Carbon Flux By Carbon Cycle Model In The Northern South China Sea

A carbon cycle model was set up to study air-sea carbon flux in the northern South China Sea. The model takes into account the processes including the air-sea carbon flux, the hydrodynamis, the ecological dynamics. The model contains three major parts: hydrodynamic part, ecological part and air-sea carbon flux part. Hydrodynamic component, ecological component and air-sea carbon flux component were correspondingly set up three sub-models.The model simulated the distribution and variety about air-sea carbon flux in the northern South China Sea. Meanwhile three numerical experiments were designed to research the response characteristics of air-sea carbon flux to environmental factors. The main results were summarized as follows:(1) The different characters of the variations about air-sea carbon flux were displayed in several representative points in the northern South China Sea. Both the pCO₂ and air-sea carbon flux showed strong seasonal signals. Their seasonal variations had larger amplitude in the Pearl River estuary than in the others.(2) In winter and in summer, both pCO₂ and air-sea carbon flux had distinctive patterns in the northern South China Sea. In winter, the ocean pCO₂ was less than the atomspheric one, and the sea-air carbon flux was negative, and thus annual mean sea-air carbon flux was about -0.3 mol m^-2 y^-1. The northern South China Sea was the weak sink to atmospheric CO₂. In summer, the ocean pCO₂ was more than the atomspheric one, and the sea-air carbon flux was positive, and thus annual mean sea-air carbon flux was about 0.9 mol m^-2 y^-1. The northern South China Sea was the weak source to atmospheric CO₂. The whole year average of the air-sea carbon flux was about 0.3 mol m^-2 y^-1, generally speaking, the northern South China Sea was the weak sink of air CO2.(3) Both pCO₂ and air-sea carbon flux were found dominated by the loadings in the Pearl River estuary, and that their distributions were very complicated.(4) The biology effect in the northern South China Sea was very weak. The ocean primary production was dominated by nutrient availablity. (5) The hydrodynamics was the dominant factor for the pCO₂ and sea-air carbon flux in the northern South China Sea.