1961—2010年山西省寒潮的气候特征与可能成因

Climatology of the Cold Wave Events of Shanxi Province in 1961-2010 and the Possible Reasons

利用山西71个台站逐日气温资料和NCEP 500 hPa高度场、海平面气压场、海温格点场再分析资料,采用Kendall-tau非参数方法、Mann-Kendall突变检验和相关分析法,研究山西1961—2010年寒潮的变化特征。结果表明,1961年以来,山西寒潮日数呈减少趋势,但存在区域差异,北部寒潮减少,中部寒潮增加,南部变化不明显。近50年来,山西寒潮强度变化趋势不明显,但年代际差异显著。20世纪90年代以来,山西寒潮初次出现的日期在推迟,而寒潮结束的日期却在提前,这种特征在进入21世纪以后表现更为突出。气候变暖导致山西寒潮频次减少,寒潮开始迟、结束早,全省范围寒潮的极端天气在增加。环流形势相关分析表明,500 hPa高纬度的高度正异常配合乌拉尔山、贝加尔湖附近等的高度负异常与山西寒潮频次密切相关。冬季来自北冰洋、西西伯利亚和东西伯利亚的冷空气是寒潮的主要来源。北大西洋海温场北负南正的偶极子模态与山西寒潮频次有较密切的联系,可作为寒潮预测的信号场。

In this paper, the cold wave events in Shanxi Province were analyzed using Kendall-tau analysis, Mann-Kendall test and correlation analysis based on the daily temperature data observed by 71 meteorological stations and NCEP reanalysis data. The results show that the days of cold wave were decreased in recent 50 years, but the change display regional differences： reduced in Northern, increased in central region and southern did not change significantly. The intensity of cold wave did not change significantly in Shanxi Province. The date of first appeared of cold wave was postpone, meanwhile, the date of final was postpone, and the feature is more prominent in the 21st century. Warming leads to decrease of the frequency of cold wave, and cold wave start late, end early. Moreover, the frequency of province-wide cold wave, such extreme weather was increased. There was significant correlation between the frequency of cold wave in Shanxi Province and the positive anomaly of height at high latitudes coordinate the negative anomalies of height at Ural Mountains, Lake Baikal etc. in 500hPa height field. The cold air come from the Arctic Ocean, West Siberia and the East Siberian in winter is major source of cold wave. The dipole mode in North Atlantic sea surface temperature field contact closely with the cold wave in Shanxi Province, it may act as predicted signal field.