近50 a ENSO时频特征及其与南海台风的相关性

Study on ENSO Time-frequency Characteristics in Recent 50 Years and Its Correlation with Typhoon in the South China Sea

【目的】分析表征ENSO事件的特征值和南海台风活动的多时间尺度结构特征及其相关关系。【方法】采用日本气象厅东京台风中心(JMA)1967-2016年西北太平洋TC最佳路径数据集,统计分析了近50 a来南海台风活动月频数。同时又采用Morlet小波变换、交叉小波变换、小波相干等方法,分析了近50 a来ENSO事件时频变化特征及其与南海台风相关性。【结果与结论】ENSO循环具有2-6 a的主周期;7-10月南海台风活动最为频繁,其频数时间序列存在准2 a尺度周期;ENSO指数与南海台风活动频数的相关表现在多个时间尺度上。1970-1978年、1995-2000年,ONI指数和南海台风活动频数在2-6 a周期尺度上具有较好的相关关系,并且南海台风活动频数变化先于ONI指数半个周期。1980-1985年间,在1.5-3 a的周期尺度上SOI指数和南海台风活动频数具有较好的相关关系,且两序列同步变化。

【Objective】 This paper attempts to analyze the characteristic value of the ENSO events and the multitime-scale structural features of the South China Sea typhoon activity and their correlations. 【Methods】Using the Japan Meteorological Agency＇s（JMA） 1967 – 2016 TC best path data set of the Pacific Northwest, the monthly frequency of typhoon activity in the South China Sea during the past 50 years was statistically analyzed. At the same time, Morlet wavelet transform, cross wavelet transform, wavelet coherence and other methods were used to analyze the time-frequency characteristics of ENSO events in the past 50 years and its correlation with typhoon in the South China Sea. 【Results and Conclusions】The results show that the ENSO cycle had has a main period of 2 – 6 a, with the most frequent typhoon activity in the South China Sea. and its frequency time series has a quasi-2 a scale cycle, The correlation between the ENSO index and the frequency of South China Sea typhoon activity was on multiple time scales. In 1970 – 1978 and 1995 – 2000, the ONI index and the South China Sea typhoon activity frequency had a good correlation on the 2 – 6 a cycle scale, and the frequency of changes in the South China Sea typhoon activity preceded the ONI index by half a cycle. From 1980 to 1985, there was a good correlation between the SOI index and the frequency of South China Sea typhoon activity on the scale of 1.5-3 years, and the two sequences changed simultaneously.