中国夏季东北冷涡强度的定量化分析

本文利用NCEP/NCAR发布的1981~2010年全球日平均再分析位势高度场资料对东北冷涡进行检索并提取其平均态, 在此基础上定义东北冷涡的偏离指数, 并探讨其对东北冷涡强度特征的描述。结果表明: (1) 东北冷涡500 hPa闭合中心位势高度的概率分布近似为高斯分布, 以其期望值提取的东北冷涡平均态具有东北冷涡的共性, 表现出明显的大气斜压性及有利于系统维持和发展的温压配置关系特征; (2) 基于东北冷涡平均态定义的东北冷涡偏离指数不仅能够表征东北冷涡偏离平均态的程度, 还包含了低压面积的信息, 即能够直观地显示东北冷涡的强弱特征。

The Quantitative Research on Cold Vortex in Summer over Northeast China

Using daily reanalysis data, released by NCEP/NCAR, about geopotential height from 1981 to 2010 (30 years in total) to retrieve and analyze the cold vortex over Northeast China (CVONC), to extract and analyze the average state of CVONC, the authors define a deviation index on CVONC and discuss its rationality to depict the intensity of CVONC. It shows that: (1) the probability distribution of CVONC's geopotential height of occlusive center at 500 hPa is similar to the Gaussian normal distribution, and the average state of CVONC extracted by the expected value of Gaussian normal distribution hold general characters of CVONC; (2) the definition of deviation index on CVONC based on its average state could represent not only the deflected degree from the average state of CVONC, but also some information about the areas of low pressure, which means that it could indicate the intensity characteristics of CVONC directly.