近58年华北地区初、终霜日及无霜期变化特征分析

基于华北地区90个气象站点1961-2018年地面0 cm日最低温度和平均气温资料,采用线性倾向估计、反距离加权、Mann-Kendall检验、累积距平法,研究了近58年华北地区初、终霜日和无霜期的变化特征。结果表明:(1)在年际和年代际尺度上,华北地区初、终霜日和无霜期均分别呈显著推迟、提前和延长的趋势,从20世纪80年代开始,趋势逐渐明显,反映出气候的变暖趋势。(2)由北向南随纬度和海拔的降低,初、终霜日和无霜期分别呈推迟、提前和延长的趋势,平均气温上升速率越大越显著的站点,其初、终霜日和无霜期推迟、提前和延长的速率也较显著;山区初、终霜日和无霜期分别比平原早、晚和短。(3)初、终霜日和无霜期突变分别发生在1986,1995和1995年,各区域初、终霜日和无霜期均在20世纪80年代和90年代发生突变。(4)初、终霜日和无霜期的等值线呈北移趋势。(5)初、终霜日和无霜期在未来分别呈持续推迟、持续提前和持续延长的趋势,且三者的变化幅度为无霜期>终霜日>初霜日。

Variation Characteristics of the Date of First Frost and Last Frost and the Frost-Free Period in North China in Recent 58 Years

Frost will seriously affect normal agricultural activities. It is of great significance to know and grasp the changing characteristics of the first frost and last frost and the frost-free period to guide agricultural production practices,improve the prevention and early warning capabilities of frost disasters. Based on the ground 0 cm daily minimum temperature and average temperature data of 90 stations(1961-2018)in over North China,using the methods of linear regression,inverse distance weighted,Mann-Kendal test and cumulative anomaly to analyze the variation characteristics of the first frost and last frost and the frost-free period in North China. The results show that:(1)In terms of time changes,the first frost date,the last frost date and the frost-free period showing the significant trends in delay,advance and extension,respectively,which gradually became obvious from the 1980 s;The changing characteristics of the frost reflects the climate warming.(2)Along with the decrease of the latitude and the altitude,the first frost date,the last frost date and the frost-free period show trends of delay,advance and extension,respectively. And if the average temperature at the station raised significantly,the rate of delay,advance and extension of the initial,final and frost-free periods is also significant;The first frost date,the last frost date and the frost-free period in the mountain are earlier,later and shorter than those in the plain,respectively.(3)The mutation years of first frost date,last frost date and the frost-free period were1986,1995 and 1995,respectively. And the mutation years of the frost in the three sub-regions all occurred in the 1980 s and 1990 s.(4)Based on different climatic reference periods and different decadal,The locations of the contour lines of the first frost date,the last frost date and the frost-free period all gradually moving northward.(5)The changes in the predicted frost period are roughly the delay of the first frost date,the advance of the last frost date,and the prolonged frost-free period. But there is a slight difference in the magnitude of the change with the descending order of frost-free period,last frost date and first frost date.