西秦岭及周边地区1951～2010年气温变化的时空分布特征

以西秦岭及周边地区12个气象站点的1951～2010年气温序列为研究对象,采用5年滑动平均、线性回归、Mann-Kendall非参数统计检验、经验正交函数等方法,分析西秦岭及周边地区1951年以来的年平均气温距平、年平均最高气温及年平均最低气温变化的时空分布特征,并用小波变换分析其长期变化特性,揭示其变化规律。结果表明,西秦岭及周边地区近60年升温速率为0.18℃/10a,低于同期全国0.22℃/10a的速率,但升温趋势明显,尤其是年平均最低气温,其升温趋势系数达0.55,且通过信度为0.001的显著性检验。EOF分解发现,年平均气温距平场和年平均最高、年平均最低气温场的的第1特征向量的方差贡献均在90%左右,在整个区域上均表现出一致的特征,均为正值或均为负值,即在整个区域气温变化格局一致,但年平均最高气温呈反向分布;年平均气温距平及年平均最高气温的第2模态表现出正负相间的分布,而年平均最低气温的第2模态以天水-岷县-若尔盖为界西北、东南呈反向分布,同时3个要素的低值中心均在宝鸡附近。小波变换分析表明年平均最低气温有6年的准周期振荡,在1990年以前振荡最突出,1990年之后以36年的长期振荡为主。

Temporal and Spatial Distribution Features of the Annual Temperature Variation in 1951-2010 at the West Qinling Mountains and Its Surrounding Areas

According to the temperature data of 12 weather stations in West Qinling Mountains and its surrounding areas during 1951-2010,the spatial and temporal distribution features of annual average temperature anomaly,annual average highest temperature and lowest temperature in this area were analyzed by the methods of five year moving average,linear regression,Mann-Kendall non-parametric statistics test,and empirical orthogonal functions.And then the long-term variation characteristics and rules of temperature were exposed by the wavelet transform analysis.As indicated by the results,the temperature in this area increased at a rate of 0.18 ℃/10a during the past 60 years,lower than the national rate of 0.22 ℃/10a,however,the warming trend is obvious,especially the average annual minimum temperature with the warming trend of 0.55,which passes the 0.001 significance test.The analysis results using empirical orthogonal function method show that the explained variances of the first eigenvector of the annual average temperature anomaly field,the annual average maximum field and annual average minimum temperature field are more than 90%,and show the same characteristics at the whole areas,but the annual average maximum temperature is reversely distributed.The second modes of the annual average temperature anomalies and annual average maximum temperature show the distribution of positive and negative phase,while the second mode of the average minimum temperature shows a reverse distribution in the northwest and southeast side of Tianshui-Minxian-Ruoergai boundary.The low value center of all three elements is around Baoji.The wavelet transform analysis shows that the average annual minimum temperature has a 6-year quasi-periodic oscillation before 1990 and a 36-year oscillation after 1990.