Upwelling of cold water in the South Yellow Sea alleviates phosphorus and silicon limitations

Abstract Upwelling in the South Yellow Sea is a phenomenon that plays an important role in nutrient transport and biological productivity. Based on remote sensing data from 2000 to 2022 and in situ observations from 2012 to 2022, we investigated the interannual variability of cold‐water mass frontal upwelling and its contribution to the transport of nutrients in the South Yellow Sea. The results showed that the upwelling positions during summer were consistent with the fronts of the cold‐water masses. The influence of upwelling on nutrient distribution and transport varied interannually, and the El Niño‐Southern Oscillation during winter might influence the intensity of summer frontal upwelling by modulating summer winds. Nutrient fluxes via upwelling from 2012 to 2022 were estimated: 0.08 × 10 8 –25.9 × 10 8 mol month −1 of dissolved inorganic nitrogen, 0.003 × 10 8 –0.67 × 10 8 mol month −1 of dissolved inorganic phosphate, and 0.12 × 10 8 –40.8 × 10 8 mol month −1 of dissolved silicate. Nutrient fluxes during summer were comparable to the summer inputs from the Changjiang River. The dissolved inorganic nitrogen/dissolved inorganic phosphate ratio in frontal upwelling decreased from 38.6 in 2012 to 20.0 in 2022, and the dissolved silicate/dissolved inorganic nitrogen ratio increased from 0.93 in 2012 to 2.48 in 2022. Nutrient composition and fluxes carried by upwelling can alleviate the limitations of both phosphorus and silicon in the South Yellow Sea. Upwelling nutrients in the frontal zone of the Yellow Sea Cold Water Mass could promote local phytoplankton growth and contribute to the development of Ulva prolifera .