辽宁区域性冷空气多时间尺度变化特征及影响因子

使用辽宁省58个气象观测站1961年9月-2015年4月气温资料、国家气候中心气候监测指数和NCEP分析资料,分析了辽宁区域性冷空气的多时间尺度变化特征及影响因子.结果表明:辽宁区域性强冷空气、寒潮年总频次都呈下降趋势,而中等强度冷空气年总频次呈上升趋势,冷空气强度有减弱的趋势.区域性冷空气过程年总频次存在11 a、6 a和3 a的变化周期,并且1964年发生突变.秋季冷空气活动最频繁,冬季冷空气强度最强.区域性冷空气初日多年平均值是9月23日,终日多年平均是4月5日,初、终日都出现提前趋势.北半球极涡面积指数与辽宁寒潮频次呈明显正相关关系,寒潮偏多月份极涡较气候平均位置偏南、50°N附近70°~180°E之间纬向风明显偏大,是辽宁寒潮增多的影响因子.

Multiple-time scale variations and impact factors of regional cold air in Liaoning Province

Based on the observational data of temperature and climate monitoring index from the national cli-mate center and NCEP,the multiple time scale variations and impact factors of regional cold air in Liaoning Province are analyzed. The analysis shows that the frequencies of regional strong cold air and cold wave have sig-nificantly decreased,but the frequency of moderate intensity cold air has increased. Cold air strength has weak-en. There are changing periods of 11-year,6-year and 3-year for regional cold air. The frequency of the regional cold air had an abrupt change in 1964. The season with most frequent cold air activity is autumn and the season with strongest cold air is winter. The average first regional cold air date is on September 23 and the last date is on April 5,and the first and the last dates are going to shift to an earlier date. The polar vortex area index in the northern hemisphere has a significant positive correlation with the frequency of the regional cold wave. In more cold wave months,the polar vortex will shift south as compared with that in normal month,and the zonal wind between 70°- 180° E and near 50° N is larger than normal. The polar vortex and the zonal wind are the pro-nounced factors of increasing regional cold air in Liaoning Province.