||Internal waves occur frequently near Dongsha Atoll in the South China Sea. Vertical mixing induced by these waves may entrain cold nutrient-rich water from subsurface layer to surface layer, and resulting in high concentration of chlorophyll due to enhanced photosynthesis. A numerical study on the impact of internal waves on biogeochemistry in Dongsha area is executed. MODIS chlorophyll data is used to validate the relationship among nutrient, phytoplankton and zooplankton.|
When NPZ model runs 200 days, there is a significant interaction between any two of nutrient, phytoplankton and zooplankton (nutrient vs. phytoplankton, nutrient vs. zooplankton, or phytoplankton vs. zooplankton) and there is no interaction with the left one.The sum of the concentration of nutrient, phytoplankton and zooplankton are called NPZ mode threshold value. When the sum of three concentrations reaches NPZ mode threshold value, there will be a significant interaction among nutrient, phytoplankton and zooplankton. If the maximum growth rates of phytoplankton (Vm) are set to be 1, 2, and 3, the NPZ mode threshold values are about 1.6~2.0, 2.1~2.2, and 2.2~2.5 m mol N m-3, respectively.
In this study, the variation of the biomasses corresponding to nutrient, phytoplankton and zooplankton is simulated by an interacting Nutrient-Phytoplankton-Zooplankton (NPZ) model. The results show that the chlorophyll blooms in two days after cold water intrusion. Three days after the bloom, the concentration of zooplankton reaches its peak value.