冬季北太平洋风暴轴的年代际变化

Interdecadal Variations of North Pacific Storm Tracks in Winter

摘要:

对1948—2004 NCEP/NCAR 500 hPa高度场资料进行滤波后,采用累积距平、Morlet小波分析、合成分析等方法,研究了风暴轴中心的强度、经纬度以及面积指数的年代际变化。结果表明,56 a来北太平洋风暴轴的中心强度平均约为32 dagpm²,中心位置约在172°W、44.5°N。小波分析表明,冬季北太平洋风暴轴的中心强度和面积都存在着18 a的年代际变化周期。此外,风暴轴中心强度与面积指数有很好的正相关关系。总的来说,风暴轴中心强度增强(减弱)时期,一般对应着风暴轴面积增大(缩小)和位置向西(东)、向南(北)移动。

Abstract:

Based on the NECP/NCAR daily reanalysis data from 1948 to 2004 using the methods of filtering accumulative anomaly,Morlet wavelet transform and composite analysis,we studied the inter-decadal variation characteristics of the intensity,longitude,latitude and area index of North Pacific storm tracks,and found that the mean intensity of storm track centers during the 56-yr is about 32 dagpm² and it locates at about 44.5°N,172°W.Morlet wavelet analysis indicates that its strongest interdecadal periodical signal is 18-yr.Besides,the intensity of the centre and area index of storm tracks have a good mutual corresponding relationship.Generally,when the intensity becomes strong(weak),the area expands(shrinks) with a westward(eastward) and southward(northward) shift of the center.