南海的热带气旋(TC)活动对南海沿岸尤其是我国华南地区的经济和生活有着直接的影响，因此提高南海TC活动预报不仅具有科学意义也有重要的社会意义。近年来，对南海TC的频数和路径方面的预报能力有所提高，但是对强度尤其是强度迅速变化（RI）的预报则仍然没有显著的改善。申请人已有的关于季节内振荡（ISO)对南海和西太平洋TC活动的影响研究揭示了ISO对TC活动变化的重要性。尤其，南海处于印太暖池的中心区域，是ISO北传支的主要途径海域。因此本项目采用观测、统计方法和数值模拟相结合的方法研究ISO活动对南海TC RI的影响，从能量分析角度量化ISO各要素对TC RI影响的贡献。本项目的研究将为提高南海TC强度预报的改善提供理论依据。

Tropical cyclones (TCs) in the South China Sea (SCS) have direct impact on the economic and human activities along the SCS coast, especially southern China, therefore, improving the prediction skill of TC in the SCS has significance both scientifically and socially. In recent years, there are some improvements in the capability of predicting TC genesis and tracks, however, little progress has been made regarding the prediction of TC intensity, especially rapid intensification (RI). Previous works done by the applicant have revealed that ISO has strong impact on the TC tracks and intensity. More importantly, the SCS is located in the center of Indo-Pacific warm pool, and is also the area through which ISO propagate northward. The project will study the impact of ISO on TC RI based on observation, statistic methods and modal simulation and quantify the contribution of individual component related to ISO on the TC RI. The finding from this project can provide scientific and theoretic foundation for the prediction of TC intensity.