黑龙江省冬季异常冷气候事件判定及其与环流指数的关系

Diagnosis of Winter Abnormal Cold Climate Events in Heilongjiang Province and Their Relationship with Circulation Indices

以连续5 d日平均气温负距平超过1倍标准差为标准,对黑龙江省冬季异常冷气候事件进行了判断。经普查,黑龙江省1961-2018年冬季共发生51次异常冷气候事件,累计天数428 d。1961-1986年为高发期,平均年发生1.31次,次均天数为9 d;1987-2008年为低发期,平均年发生0.32次,次均天数为9 d;2009-2018年为较高发生期,平均年发生1次,次均天数为5.9 d。在异常冷气候事件低发期,发生次数较少,但每次事件持续时间更长。最近10年异常冷气候事件发生较多,但每次持续时间较短。以0.3个标准差作为等级划分标准,1961-2018年该省冬季发生一级、二级、三级异常冷气候事件分别为13次、14次、24次,其中一级多发生在1986年前。为了揭示异常冷气候事件发生的天气气候机制,分析了该事件与月尺度同期环流指数异常的对应关系。北半球极涡面积异常偏大、极涡强度异常偏弱、东亚槽位置异常偏西和AO异常负位相与异常冷气候事件发生有较好的对应关系,尤其是12月、1月的北半球极涡面积,12月东亚槽位置,1、2月东亚槽强度和2月AO,为研究该省异常冷气候事件的形成机理和预测提供了参考。

According to the criterion of daily average negative temperature anomaly exceeding 1 standard deviation for 5 consecutive days, there were 51 abnormal cold climate events in the winter of 1961-2018 in Heilongjiang Province, with a total of 428 days. 1961-1986 was the high incidence period, with an average annual occurrence of 1.31 times, and the average number of days was 9 d;1987-2008 was the low incidence period, with an average annual occurrence of 0.32 times, and the average number of days was 9 d;2009-2018 was the second high incidence,with an average annual occurrence of 1 time and the average number of days is 5.9 d. In the period of low incidence, the number of occurrences is less, but each event lasts longer. There have been more abnormal cold climate events in the recent 10 years, but each time has a shorter duration.Taking 0.3 standard deviations as the classification criteria, the level 1, the level 2, the level 3 events occurred in Heilongjiang Province during 1961-2018 were 13 times, 14 times, and 24 times,respectively, most of level 1 events occurred before the year of 1986. In order to reveal the weather-climate mechanism of the occurrence of abnormal cold climate events, the correspondence relationship between the abnormal cold climate events and the monthly circulation index anomalies was analyzed. The hemispheric polar vortex area is abnormally large, the polar vortex intensity is abnormally weak, the eastward trough location is abnormally westward, and the AO abnormal negative phase has a good correspondence with the occurrence of abnormal cold weather events. The research results provide a reference for studying the formation mechanism and prediction of abnormal cold weather events in the province.