冬季北太平洋风暴轴纬向变化特征及其与我国极端低温频次的可能联系

采用NCEP/NCAR和ERA40再分析资料,分析了垂直方向上冬季北太平洋风暴轴纬向结构的时空演变特征,揭示了北太平风暴轴纬向结构具有显著年际、年代际变化特征。冬季北太平洋风暴轴纬向结构主要呈现出全区一致、东西反相两种分布型("A"型和"B"型),细分为整体一致性强型("A+"型)、整体一致性弱型("A-"型)、东弱西强型("B+"型)和东强西弱型("B-"型)。研究表明:冬季北太平洋风暴轴的纬向结构与我国极端低温频次的关系密切,风暴轴呈"A+"("A-")型纬向结构时,我国整体区域极端低温频次偏少(多);风暴轴呈"B+"("B-")纬向结构时,我国全区极端低温频次偏多(少)。

Zonal variation characteristics of the North Pacific storm track in winter and its relation with the frequency of extreme low temperature activity in China

On the basis of NCEP/NCAR reanalysis data and ERA40 reanalysis data, the spatiotemporal evolution characteristics of the zonal structure of the North Pacific storm track in winter are studied. Results show that the zonal structure of North Pacific storm track has evident interannual and interdecadal change characteristics. Two main zonal structure modes exist in North Pacific storm track, which are a consistent mode in the entire region("A" mode), and the east-west direction opposite mode ("B" mode). Moreover, the two main modes can be divided into four zonal anomalous types:consistently strong pattern ("A+" pattern), consistently weak pattern ("A-" pattern), weak east and strong west pattern ("B+" pattern), and strong east and weak west pattern ("B-" pattern). Furthermore, the zonal structures of the storm track are closely related to the frequency of the extreme low temperature in China, which means that the "A+" pattern("A-" pattern) correlates strongly to the less (more) extreme low temperature events in entire China, while "B+" pattern("B-" pattern) correlates strongly to the more(less) extreme low temperature in entire China.