1979—2019年持续性东北冷涡过程特征分析

利用1979年1月至2019年12月的ERA5资料，采用小波分析、突变M-K检验等统计方法，对1979—2019年持续时间在3 d及以上的东北冷涡过程特征进行分析。结果表明: 持续性东北冷涡过程的年平均发生次数为32.8次，最多41次，最少22次; 其中5—6月最多。年总频次存在17 a、9 a、5 a和3 a的变化周期。东北冷涡过程持续时间越长，出现的几率越小，持续时间最长的一次为13 d; 持续3 d的东北冷涡过程最多，持续9 d和10 d的过程出现频率接近十年一遇，出现10 d以上的冷涡过程6月最多。南涡出现的频次明显少于北涡和中涡，中涡最多; 北涡各月频次差异不明显，中涡、南涡5月和6月明显多于其他月份。在120°—130°E、45°—55°N的区域冷涡中心相对密集。夏、冬半年东北冷涡极端偏多月份东亚地区均为两脊一槽型。

Characteristics of the continuous cold vortex over Northeast China from 1979 to 2019

Using ERA5 reanalysis data from 1979 to 2019, the characteristics of the northeast cold vortex with a lifetime of > 3 days during the forty years were analyzed using statistical methods including the Morlet wavelet and Mann-Kendall test.The results show that the continuous northeast cold vortex occurred 32.8 times on average, with a maximum of 41 times and a minimum of 22 times per year.The continuous northeast cold vortex process mostly happened in May and June and the cycles of annual times were 17 years, 9 years, 5 years and 3 years, respectively.The longer the duration of northeast cold vortex processes were, the less frequent they may occur.The longest duration could reach 13 days and those lasted 3 or 4 days appeared most frequently.The durations reaching 9 or 10 days occurred once per ten years and those lasted more than ten days appeared most significantly in June.The frequencies from high to low were the central vortex, north vortex and south vortex, with little monthly differences for the north vortex and much more during May and June for the center and south vortex.The cold vortex centers were most located in the region of 120°-130°E, 45°-55°N, and the pattern of two troughs and one ridge was the unique circulation background in the northeast cold vortex extreme months during both summer and winter half years over East Asia.