近51年山东临沂市冷暖冬气候特征及其成因分析

Analysis of Climate Characteristics and Causes of Cold and Warm Winter Over Linyi City in Recent 51 Years

为了掌握临沂市冬季气候特征及其冷暖冬的成因,减少冷暖冬对农业生产的不利影响,以便更有效利用冬季气候资源服务于临沂地区农业生产,利用临沂市1961—2011年12—2月气温观测资料,采用统计方法进行气候诊断研究,分析了临沂市近51年冬季平均气温的变化趋势,在此基础上,依据中国国家标准《暖冬等级》,参照单站、区域暖冬等级标准,确定了单站和区域冷冬等级,统计分析了1961—2011年临沂10个站冷、暖冬事件的气候变化特征。结果表明：近51年临沂各地冬季平均气温呈明显升高趋势,尤其是在20世纪90年代以后表现更为明显。临沂单站和区域暖冬指数均呈显著上升趋势,51年区域暖冬事件共发生10次,强暖冬3次,主要出现在20世纪90年代以后。各站冷冬事件发生频率为47%~59%,强冷冬频率为20%~31%。区域冷冬指数呈-17.7%/10 a的显著下降趋势,区域冷冬事件共发生27次,其中强冷冬14次,主要出现在20世纪80年代以前,20世纪90年代以后显著减少,与暖冬成相反的变化趋势。冷暖冬的成因主要归咎于温室效应、东亚冬季风、西太平洋副热带高压、ESNO等因素,其中最重要、最直接的原因取决于南下冷空气的强度和频率,冷空气强且频,其冬必冷,冷空气强度小、频率低,则易出现暖冬。

In order to grasp the based on the 12 to 2 monthly climatic characteristics and causes average temperature data in Linyi of cold and warm winter over Linyi City, from 1961 to 2011, using the statistical methods to climate diagnostic studies, the variation trend of winter mean temperature over Linyi during recent 51 years was analyzed, on this basis, according to the China national standard warm winter grade and referring to single station and regional warm winter grade standards, the grade of single station and regional cold winter were determined. On the basis of the division method for cold and warm winter, the author analyzed the climatic change events of 10 stations＇ cold and warm winter in Linyi from 1961 to 2011. The results showed that： the trend of average temperature in winter increased significantly over Linyi, especially more obvious since the 1990s. Both IWs and IWa showed a significant upward trend, there were 10 regional warm winter years over the 51 years with 3 strong warm winter, and mainly after the 1990s, the frequency of single cold winter was 47%-59% with 20%-31% of strong cold winters, and ICd showed a significant decreasing trend at a decadal rate of- 17.7%. There were 27 regional cold winter years over the 51 years with 14 strong cold winters, and mainly before the 1980s, significantly reduced after 1990s. The main factors of cold and warm winter attributed to the greenhouse effect, the weaken east Asian winter monsoon, the strengthened subtropical high in the western Pacific, ESNO etc, one of the most important and direct reason depended on the intensity and frequency of cold air, strong and frequent cold air, it would be a cold winter, and weak and low frequency was prone to warm winter.