临汾市近30年终霜冻变化规律及特征分析

An analysis of the variation rules and features of last frost over recent 30 years in Linfen City,Shanxi Province

选取临汾市17个气象站1981—2010年近30 a的3—5月份0 cm日最低温度≤0℃的值,以此来确定春霜冻期和终霜冻日.采用线性倾向法,分析临汾市东西南北中5区近30 a春霜冻的年际变化规律;应用MK间断点分析法对霜冻结束日期序列进行突变检验.对临汾市近30年5个区域的霜冻日期进行连续小波变换,得到小波变换系数的实部等值线图及小波方差图.结果表明:(1)临汾市北部(-2.1 d/10 a)、西部(-5.2 d/10a)、中部(-2.4 d/10 a)终霜冻日有明显提前的趋势,南部(-0.7 d/10 a)有缓慢提前的趋势,而东部(0.4 d/10 a)有缓慢推后的趋势;终霜冻强度气候倾向率在-0.1~0.3 d/10 a之间,各区域有变化,但不明显.(2)临汾市东部、中部和南部,突变年份均在2007年.西部突变出现在1990年,北部突变出现在1997年.突变后表现为东南早,西北晚.(3)各区域皆存在7 a的主周期,次周期除临汾市中部地区为8 a外,其它地区的次周期皆为11 a.以上规律结论的得出为临汾霜冻预报提供了理论根据,对指导当地的农业生产具有重要的意义.

Applying data of daily lowest ground temperature less than 0 ~C through March to May of 17 mete- orological stations in Linfen District,Shanxi Province,over 30 years from 1981--2010,we have done a research on determining the spring frost and the last frost date.Using linear trend analysis method, the interannual variation of the spring frost in Linfen District has been analyzed.Meanwhile the Mann-Kendall discontinuity analysis meth- od has been used to test mutations in the sequence of the end dates of frost and the contour maps of the real part of wavelet transformation coefficients and wavelet variance maps have been depicted by conducting the continuous wavelet transform on the end frost dates.The results show that firstly the end dates of frost advance obviously in the north,west and middle parts of Linfen District, the south part presents a slow advance trend, while the east part has the slow delay trend. The climate tendency rates of frost intensity in each region vary, but not obvious. Secondly, the mutation year in eastern, central and southern parts of Linfen appears in 2007, while the mutation year in western Einfen is 1990, and in northern Linfen the mutation occurred in 1997.The trend after the mutation is advancing in east and south while delaying in west and north.Each region has the main cycle of 7 a.The sub cycle, in addition to the central region of Linfen district for 8 a, is 11 a for the other regions.The above conclusions provide a theoretical basis for the prediction of frost in Linfen,which is also of great significance for guiding the local agricultural production.