Coccolithophores, originating in the Late Triassic, are one of the most successful marine calcifying algae living in modern oceans. Coccoliths are the calcareous fossil remnants left in marine sediments after coccolithophores die. These calcite scales record the conditions of the surface ocean (e.g., primary productivity, seawater temperature, and carbonate chemistry) and are expected to be a promising subject in paleoceanographic and paleoclimatic studies. Hence, a comprehensive understanding of the ecology and phenology of living coccolithophores, as well as their interactions with other plankton groups, is needed to develop better constraints on their uses in paleoenvironmental studies. Here we show modern coccolithophore production through the coccolith fluxes from sediment traps at a ~500‐m water depth from 2013 to 2015 in the northern South China Sea. In addition to the expected seasonality of the coccolithophore production that occurs during winter seasons due to the strong water mixing induced by monsoon winds, a two‐stage mode for the coccolithophore production is also recognized in relatively “coastal” waters. The first stage includes the production of Gephyrocapsa oceanica in December, when the macronutrient inventory is built, and the second stage describes the growth of Emiliania huxleyi in late February with the depletion of silicate nutrients. This two‐stage mode originates from subtle differences in the nutrient assimilation ability between the two species. In addition, coccolithophore production is significantly influenced by the decadal oceanic events (i.e., El Niño) in the northern South China Sea.

The static and dynamic characteristics of the EDM machine as the main machining unit directly influence the machining accuracy and stability. For a particular type of the EDM machine, the three-dimensional model was built with SolidWorks and the finite element method was employed with the ANSYS Workbench to analyze the static and dynamic characteristics of the machine. The results show that the stiffness of the ram and vertical guide (Z-axis) in the Y and Z directions is the weak side of the machine. The analytical method is proved to be effective for the optimization of the machine design.

The strontium‐to‐calcium (Sr/Ca) ratio of coral is widely used as a paleothermometer for tropical sea surface temperature (SST) at subannual resolutions. The fidelity of Sr/Ca‐derived SST estimates largely depends on the properties of the monthly age model selected. Here, we develop a revised monthly age model for coral Sr/Ca estimation from the northern South China Sea based on specific tie points and evaluate the impacts of different age models on SST reconstruction. Our results indicate that our revised monthly age model reduces conversion errors by up to nearly 20%–30% relative to previously reported values, thereby improving the precision of seasonal SST estimates and enabling better paleoclimate interpretations, such as El Niño–Southern Oscillation variability. The revised monthly age model provides a generalized approach for developing more robust seasonal resolution Sr/Ca–SST reconstructions in other regions.