西北太平洋热带气旋累积能量与ENSO相关性的年代际变化

Decadal Shift in the Relationship between Accumulated Cyclone Energy of Tropical Cyclones in the Northwest Pacific and ENSO

摘要: 文章利用中国气象局发布的热带气旋(TC)最佳路径数据资料，以及NCEP/NCAR大气再分析数据，分析了盛季(7~9月份)、后季(10~11月份)西北太平洋(WNP)TC累积气旋能量(ACE)与ENSO事件相关性的年代际变化。发现WNP TC盛季ACE与ENSO的相关性在1980年发生了年代际的突变，二者相关性由不显著变为显著的正相关。TC后季ACE与ENSO的相关性在1990年前后发生了年代际的突变，相关性由不相关变为显著的正相关。盛季、后季二者相关性年代际转变发生的事件不同，影响机制也不同。盛季ACE与ENSO相关性发生转变的主要原因是连续型ENSO在1980年之前发生频次较高，减弱了ENSO对ACE的影响。后季ACE与ENSO相关性发生转变的原因主要是1990年之前，El Niño多为东太平洋型，在WNP激发的环流异常为偶极子型分布，不能影响ACE的总量，1990年之后，El Niño发生时异常对流的位置偏西，WNP大部分区域被气旋式异常环流控制，有利于TC的生成和加强，因此TC ACE与ENSO有较好的相关性。

Abstract: This paper utilizes the best track data of tropical cyclones from the China Meteorological Administration, along with NCEP/NCAR reanalysis atmospheric data, to analyze the decadal shift in the relationship between the Accumulated Cyclone Energy (ACE) of tropical cyclones (TC) in the Northwest Pacific (WNP) during the peak (July-September) and late (October-November) seasons and ENSO events. It was found that the correlation between WNP TC ACE during the peak season and ENSO underwent a decadal shift in 1980, changing from non-significant to a significant positive correlation. The correlation between late-season TC ACE and ENSO also experienced a decadal shift around 1990, changing from no correlation to a significant positive correlation. The decadal shifts in correlation during the peak and late seasons occurred at different times and were driven by different mechanisms. The shift in the correlation between peak season TC ACE and ENSO is primarily due to the high frequency of continuous-type ENSO events before 1980, which weakened the influence of ENSO on ACE. The reason for the shift in the correlation between late-season TC ACE and ENSO is mainly because before 1990, El Niño was predominantly of the Eastern Pacific type, and the circulation anomalies it triggered in the WNP were of a dipole distribution, which did not affect the total ACE. After 1990, the position of anomalous convection during El Niño events shifted westward, and most of the WNP was controlled by cyclonic anomaly circulation, which was conducive to the generation and strengthening of TCs, hence the better correlation between TC ACE and ENSO.