华东地区热带气旋汛频数异常时的环流分析

该文是为应用统计释用预报方法对影响华东地区的热带气旋（ATC）汛频数预报所做的前期研究工作。研究发现:（1）影响华东地区的热带气旋汛频数的局地性异常变化是汛平均环流半球性调整的结果；（2）汛平均环流中的大气长波既反映了月平均环流的特征又和汛频数的变化存在着较好的关系，特别在异常年，其天气系统和相关地区也比较稳定；（3） 利用影响华东地区的热带气旋汛频数和环流变化的关系建立了汛频数的统计预报方程。在短期气候数值形势预报准确的基础上，应用统计释用预报方法所得的准确率为70%左右，若能预报出汛平均环流的异常变化，则可确定ATC汛频数的特多年或特少年。

Analysis of Circulation Field During the Abnormal Frequency of the Tropical Cyclone Affecting East China in the Flood Season

Before forecasting the frequency of the tropical cyclones affecting East China in the flood season by using statistical interpretation forecasting method, a series of earlier stage researches are made. It's found that: (1)Abnormal frequency variation of the tropical cyclone affecting East China is caused by the adjustment of mean monthly circulation of the Northern Hemisphere in flood season; (2)The long wave reflecting the characteristics of mean monthly circulation has a good relation to the abnormal frequency variation, especially in abnormal years the weather system and the correlation area are stable; (3) Using the correlation analysis the statistical forecast equation for the frequency variation of the tropical cyclone is set up.Based on the correct short range numerical forecast for climatic situation the accuracy is about 70% using statistical interpretation forecast method, and if the abnormal variation of mean monthly circulation could be predicted, the trend of abnormal frequency variation could be predicted.