北太平洋风暴轴的异常活动与辽宁省冬季最低气温的联系

利用1975-2015年辽宁省52站逐日最低气温资料和NCEP/NCAR再分析资料,通过合成分析、相关分析等统计方法,对辽宁省冬季最低气温及北太平洋风暴轴的时空演变特征进行研究,初步探讨了北太平洋风暴轴的异常活动与辽宁省冬季最低气温的可能联系。结果表明,辽宁省冬季最低气温突变年为1986年,20世纪80年代中期以后气温表现出偏暖特征。北太平洋风暴轴与辽宁省冬季最低气温间存在同步一致地变化特征,风暴轴活动强年,辽宁省受西南气流控制,阿留申低压、西伯利亚高压强度减弱,同时东亚大槽减弱北退,东亚西风急流偏北,东亚冬季风系统活动减弱,不利于冷空气向南侵袭,辽宁省冬季最低气温偏高,反之在风暴轴活动弱年,辽宁省冬季最低气温偏低。与北太平洋风暴轴相关联的中高纬度大气环流异常变化是风暴轴强度与辽宁省冬季最低气温关系产生变化的主要原因。

The North Pacific storm track anomaly and its relationship with winter minimum temperature in Liaoning Province

Based on the daily minimum temperature data from 52 observational stations in Liaoning Province and the NCEP/NCAR reanalysis data from 1975 to 2015, with composite analysis and correlation analysis, the spatial and temporal features of the winter minimum temperature in Liaoning and North Pacific storm track are analyzed, and the North Pacific storm track anomaly and its relationship with winter minimum temperature are studied. Some conclusions are drawn as follows. The winter minimum temperature in Liaoning had an obvious abrupt change around 1986, then the temperature continued to rise. The North Pacific storm track and the winter minimum temperature had synchronous consistent variation. In the years when North Pacific storm track was stronger, the winter minimum temperature was affected by the southwestern flow; at the same time, the Aleutian Low and Siberian High were at lower level, and the East Asia Trough weakened as it moved to north, the East Asian westerly jet stream at 500 hPa also moved to north. All these led to the weaker East Asian winter monsoon circulation, which was not conducive to the southward movement of cold air, leading to a higher winter temperature in Liaoning. In the years when North Pacific storm track was weaker, lower air temperature was observed in Liaoning. The main reason for the change of relationship with North Pacific storm track intensity and winter minimum temperature is anomalous change of atmospheric circulation at middle and high latitudes.