1961-2010年5-9月东北冷涡气候特征及其对辽宁气温的影响

应用1961-2010年5-9月辽宁地区逐日气温和NCEP 2.5°×2.5°资料，分析了东北冷涡的气候特征及其与辽宁气温短期变化的关系。结果表明：近50 a东北冷涡气候趋势变化不明显；年平均东北冷涡过程8.3次，平均每次过程持续3.97 d；5月东北冷涡过程次数最多，9月东北冷涡过程次数最少；5-7月平均每年受东北冷涡影响分别为7.3、7.5 d和7.4 d；东北冷涡过程次数存在13、9 a和5 a的年际变化周期。按照结构，将东北冷涡分为深厚冷涡和浅薄冷涡；受深厚北涡、中涡和南涡过程影响时，辽宁地区气温距平均为负值，而深厚中涡负距平最明显，且深厚冷涡过程持续时间越长，辽宁地区气温负距平越显著；浅薄北涡影响时，辽宁气温距平均为正值，浅薄中涡、南涡影响辽宁时，气温为弱负距平，没有深厚中涡、南涡过程影响时负距平显著，而且浅薄冷涡过程日期长短对气温影响的差异不明显。

Climatic characters of northeast cold vortex and its effect on air temperature in Liaoning province from May to September during 1961-2010

Based on the daily air temperature data in Liaoning province and the NCEP reanalysis data(2.5 ° × 2.5 °) from May to September during 1961-2010,the climatic characters of the northeast cold vortex and its effect on air temperature were analyzed.The results indicated that the variation tendency of the numbers of northeast cold vortex is not significant in recent 50 years.The mean number of annual northeast cold vortex processes is 8.3,and the mean duration of each process is 3.97 d.The northeast cold vortex often appears in May and seldom in September,and the annual mean length influenced by the northeast cold vortex in May,June and July is 7.3 d,7.5 d and 7.4 d respectively.According to a Morlet wavelet analysis method,there are 13-year,9-year and 5-year cycles for the numbers of northeast cold vortex processes.The northeast cold vortex could be divided into two types in terms of its structure,namely,deep cold vortex and shallow cold vortex.Air temperature anomalies in Liaoning province are negative when it is influenced by the deep cold vortex process,especially by the deep middle cold vortex process.The longer the duration of deep cold vortex is,the more significant the negative anomaly of air temperature is in Liaoning province.Air temperature anomalies in Liaoning province are positive when it is influenced by the north shallow cold vortex process,while anomalies are weakly negative when influenced by the central and south shallow vortexes.Furthermore,the effects of shallow cold vortex duration on air temperature are not significant.