影响广西热带气旋与海洋大气低频振荡的关联性分析

Analysis of the correlation between the Tropical Cyclone Affecting Guangxi and the Oceanic Atmospheric Low Frequency Oscillation

使用1951—2020年热带气旋资料、NCEP/NCAR再分析、PDO指数、NOAA OLR、副热带高压指数等资料,从海洋大气低频振荡角度分析影响广西热带气旋气候异常可能原因。结果表明,90年代以来影响广西热带气旋年际变化幅度增大,表现出向极端异常变化的趋势。从印度洋到西太平洋存在明显的MJO向东传播,对流抑制位相较弱、持续时间短,对流增强位相较强,影响广西热带气旋偏多。反之,从印度洋到西太平洋无MJO活动或强度较弱,存在较强的低频对流抑制带向东传播、持续时间长,较强的低频对流带位于东太平洋,影响广西热带气旋偏少。影响广西热带气旋减少趋势与PDO指数增大有密切的联系,可能与在印度洋、太平洋海温增暖背景下副热带高压强度偏强及西伸脊点偏西有关。

The p ossible causes of tropical cyclone climate anomalies affecting Guangxi were analyzed by using tropical cyclones data, NCEP/NCAR reanalysis data, PDO index data of Japan Meteorological Agency,NOAA OLR data and subtropical high index data of National Climate Center from 1951 to 2020. The results show that the interannual variation range of tropical cyclones affecting Guangxi has increased since 1990 s, showing a trend of extreme anomaly. From the Indian Ocean to the Western Pacific, there is an obvious eastward propagation of MJO, the convective suppression phase is weak, the duration is short, the convective enhancement phase is strong, and there are more tropical cyclones affecting Guangxi. On the contrary, when no MJO activity or its intensity is weak from the Indian Ocean to the Western Pacific, a strong low-frequency convection suppression zone propagates eastward for a long time, and the strong low-frequency convection zone is in the Eastern Pacific, there are few tropical cyclones affecting Guangxi. The decreasing trend of the tropical cyclone affecting Guangxi is closely related to the increase of PDO index, which may be related to the strong intensity of subtropical high and the west extension of ridge point under the background of Indian Ocean and Pacific SST warming and climate change.