【摘要】 基于气旋识别追踪算方法和ERA-Interim再分析数据,提取获得了北美北大西洋地区(20°N-80°N,130°W-0°W)1979-2012年冬季的温带气旋数据集。经统计分析表明,温带气旋的生成源地和活动范围有向西南方向漂移的趋势,且温带气旋生成源地的平均纬向、经向位置,以及其活动范围的平均经向位置与冬季NAO指数具有显著相关性。通过进一步合成分析发现,冬季NAO正位相事件期间700 h Pa强斜压性区域较负位相事件期间偏北、偏东,这在一定程度上解释了不同位相事件期间温带气旋生成源地的分布差异。NAO正位相事件期间500 h Pa的西风带位置较负位相事件期间偏北则是NAO正位相事件期间温带气旋活动范围偏北的原因。而冬季NAO正(负)位相显示出减少(增加)的趋势,进而导致了研究区域内温带气旋的生成源地向西南偏移,活动范围向南偏移。更多还原

【Abstract】 Based on the detection and track algorithm of cyclone and the ERA-Interim reanalysis data from 1979 to 2012 in winter, an extratropical cyclone dataset of North America and North Atlantic is obtained. Statistical analysis indicates that cyclogenesis areas and the scope of activities have a trend of southwestward drift. The average zonal and meridional position of cyclogenesis areas have a significant correlation with NAO index in winter, so does the meridional position of cyclone activity. Further composite analysis finds that comparing with the negative phase of NAO event, the location of 700 h Pa strong baroclinicity region is to the north and east during the positive phase of NAO event in winter, which partly explains the different distribution of cyclogenesis areas during different phase events. The 500 h Pa westerly belt position during the positive phase of NAO event is more northerly, which leads to the scope of cyclone activities northerly at that time. The NAO positive(negative) phase shows a decrease(increase) trend in winter, which brings about the southwestward migration of cyclogenesis regions and the southward migration of the scope of cyclone activities within the survey region.更多还原