西北太平洋热带气旋潜在生成指数的改进

Improvement of tropical cyclone genesis potential index in the western North Pacific Basin

热带气旋潜在生成指数(GPI,Genesis Potential Index)是热带气旋生成可能性大小的空间分布函数,利用大尺度环境场可以应用于热带气旋活动的季节预报,并且可以评估全球气候变化对热带气旋活动的影响。但是目前的GPI基本都是针对全球热带气旋活动构建的,没有考虑到热带气旋不同活动地区及其内部的差异。本研究考虑到南海和西北太平洋热带气旋生成的不同特点,分别构建了适用于南海(5～25°N,100～120°E)和西北太平洋(5～40°N,120～180°E)的热带气旋GPI。改进后的GPI对南海和西北太平洋区域热带气旋生成具有较好的模拟能力,不仅能很好地模拟南海和西北太平洋热带气旋生成频数空间分布的气候特征(相似系数为0.67),而且能够较好地模拟热带气旋生成在年际时间尺度上的空间分布特征。

The tropical cyclone genesis potential index （GPI） that is currently used for seasonal forecast of tropical cyclone activity and the associated impact of global warming has been developed on the global scale without considering regional differences in tropical cyclone activity. Based on the best -track data from the Joint Typhoon Warning Center and NCEP/NCAR reanalysis data, this study focuses on the improvement of the GPI in the western North Pacific basin. In particular, the difference of tropical cy- clone formation between the South China Sea and the western North Pacific is examined and taken into account in the new GPI. In the study, GPI is developed for the SCS （5 -25°N,100 -120 °E） and the WNP （5-40°N,120- 180°E）, respectively. The improved GPI can simulate better the climate and interannual time scale spatial distribution than previous GPIs.