冬季北太平洋风暴轴垂直结构的变化特征及其与我国极端低温事件的关系

Variation in the Vertical Structure of the Winter North Pacific Storm Track and Its Relationship with Extreme Low Temperature Activity in China

采用NCEP/NCAR和ERA-40再分析资料,对比分析了冬季垂直尺度上北太平洋风暴轴的时空演变特征,揭示了北太平风暴轴垂直结构具有显著年际变化特征。冬季北太平洋风暴轴垂直结构主要呈现出全区一致、上下反相两种分布型,细分为全区一致增强型、全区一致减弱型、上层增强下层减弱型和上层减弱下层增强型。研究表明:冬季北太平洋风暴轴的垂直结构与我国极端低温事件的关系密切,风暴轴呈全区一致增强(全区一致减弱)型垂直结构时,我国整体区域极端低温频次偏少(多);风暴轴呈上层增强下层减弱(上层减弱下层增强)型垂直结构时,我国东北地区极端低温频次偏多(少),其余地区偏少(多)。

The spatiotemporal evolution of the North Pacific storm track in winter was studied on the basis of NCEP–NCAR reanalysis data and ERA-40 reanalysis data. The results showed an evident interannual variation in the North Pacific storm track, and two main vertical structure modes were clarified. The first mode is consistent over the entire region, and the second is a vertically opposite mode. Thus, four vertically anomalous types of storm track are apparent： those with a consistently strong pattern, those with a consistently weak pattern, those with an upper-level strong and lower-level weak pattern, and those with an upper-level weak and lower-level strong pattern. It was also found that the vertical structures of the storm tracks are closely related to extreme low temperature in China. Specifically, the consistently strong pattern（consistently weak pattern） correlates closely with relatively weaker（relatively stronger） extreme low temperature over the whole of China. Meanwhile, the upper-level strong and lower-level weak pattern（upper-level weak and lower-level strong pattern） correlates closely with relatively stronger（relatively weaker） extreme low temperature in Northeast China and relatively weaker（relatively stronger） extreme low temperature in other regions.