石家庄市霜冻期的气候异常特征分析

ANALYSIS OF THE CLIMATE ANOMALIES OF FROST IN SHIJIAZHUANG

基于1955—2009年逐日最低气温资料,采用线性倾向估计法和异常霜冻指标,分析了石家庄市霜冻期的年际和年代际气候异常特征。结果表明,从气候平均上来看,石家庄市初霜冻日为11月7日,终霜冻日为3月21日,无霜冻期为230 d;石家庄市特早初霜冻发生频率为5%,偏早初霜冻发生频率16%,特晚终霜冻发生频率为4%,偏晚终霜冻发生频率为15%;大多数异常霜冻发生在20世纪50年代末至80年代;石家庄市霜冻期在90年代后,有初霜冻日推后、终霜冻日提前、无霜冻期延长的趋势;初、终霜冻日、无霜冻期的线性倾向率分别为2.85、-4.10、6.95 d(/10 a)。

Based on the 1955—2009 daily minimum temperature data,linear trend method and abnormal frost index are used to analyze the interannual and interdecadal anomalies of frost in Shijiazhuang.The results show that averagely the first frost date in Shijiazhuang is November 7,the final frost date is March 21,and the frost-free period is 230 days.The frequency of extremely early first frost is 5%,the frequency of the earlier first frost is 16%,the frequency of very late frost is 4%,and partially late frost is 15%.Most unusual frost in Shijiazhuang occurred during 1950—1980.After 1990,the first frost date was postponed,the final frost date was advanced,and the frost-free period extended.Linear tendency rates of the first frost date,final frost date and frost-free period were 2.85 days,-4.10 days and 6.95 days per 10 years,respectively.