近40年山西省初终霜日的变化特征

The Changing Trends of the First and Last Frost Dates over Shanxi Province for the Past 40 Years

利用山西省境内分布较为均匀的52个地面气象站1970-2009年的霜日观测资料,采用线性倾向估计法、累积滤波器法结合非参数统计检验方法分析了初终霜日的基本特征及其变化趋势;利用M-K法分析了霜日的突变特征。结果表明:初霜日、终霜日的出现以及无霜期的长短与地理因素密切相关,随着纬度逐渐偏北、海拔逐渐升高,初霜日提前、终霜日推后、无霜期缩短。从全省平均情况看,初霜日呈现显著的推后趋势,无霜期呈现显著的延长趋势,而终霜日的变化则以波动为主,线性变化趋势不显著。从突变检测情况看,初霜日、终霜日和无霜期在40年间均存在一次明显突变,初霜日的突变点出现在2000年,终霜日和无霜期的突变点出现在1997年。从变化趋势的空间分布看,初霜日显著推后的区域大片集中在晋中东部、吕梁北部和忻州西部,以及分散在运城南部、临汾西北部和大同南部。终霜日显著提前的区域位于晋中东部山区、吕梁山东部和忻州西部。无霜期显著延长的区域位于西北部黄河沿岸、省境中东部和运城南段。变化趋势为初霜日提前、终霜日推后和无霜期缩短的区域未通过显著性检验。

Based on the frost date data of 52 meteorological stations over Shanxi Province from 1970 to 2009,the basic characteristics of the first and last frost dates and their changing trends were analyzed in this paper using linear trend estimation method,cumulative filter method and non-parametric statistical test method respectively,and the abrupt changing feature of the frost dates was also analyzed with Mann-Kendall method.The results show that the frost dates and frost-free period have obvious spatial and temporal changing features.Along with the latitude moving northward and the altitude rising high,the first frost appears earlier,the last frost occurs later,and the frost-free period becomes shorter.With the time changing over the past 40 years,the first frost event occurs later and the frost-free period becomes longer,while the last frost date fluctuates from year to year.For the abrupt changing feature,they all have one obvious abrupt change over the past 40 years.The abrupt change of the first frost date appears in 2000,while the abrupt changes of the last frost date and the frost-free period are detected in 1997.For the spatial distribution of their changing trend,the area in which the first frost date is postponed significantly includes the east of Jinzhong city,the north of Lüliang city,the west of Xinzhou city,the south of Yuncheng city,the northwest of Linfen city and the southern part of Datong city;the area in which the last frost date appears obviously earlier includes the east mountainous region of Jinzhong city,the eastern part of Lüliang Mountains and the western part of Xinzhou city;the area in which the frost-free period extends obviously includes the region near the Yellow River,the central-eastern part of the province and the south of Yuncheng city.