冬季北太平洋风暴轴的年代际变化

Interdecadal Variations of North Pacific Storm Tracks in Winter

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。

Based on the NECP/NCAR daily reanalysis data from 1948 to 2004 using the methods of filtering accumulative anomaly, Modet wavelet transform and composite analysis, we studied the interdecadal 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. Modet 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.