利用东北地区1961—2014年日最低气温及平均气温资料,分析了近53 a初霜日、终霜日及无霜期的气候变化特征。结果表明：东北地区平均初霜日、终霜日分别为9月28日和5月5日,平均无霜期为145 d。东北地区162个站中,155个站初霜日推后,160个站终霜日提前,158个站无霜期延长,初霜日显著推后1.55 d/10 a,终霜日显著提前2.5 d/10 a,无霜期显著延长 4.08 d/10 a,霜的变化反映了气候变暖的特征（0.3 ℃/10 a）。自南向北随纬度的升高和海拔高度的抬升,初霜日提前、终霜日推后、无霜期缩短。东北地区霜的变化受最低气温的影响要大于平均气温。初霜日、终霜日及无霜期分别在1986、1989、1986年发生了突变,各省霜的突变均发生于20世纪80年代和90年代。突变后,初霜日、终霜日和无霜期多年平均等值线均向北推进。

Based on the daily minimum and average temperature data of 162 meteorological stations over the Northeast China from 1961 to 2014, the characteristics of the first frost date, the last frost date and the frost-free period in recent 53 years in Northeast China are analyzed.The results show that: the average date of the first frost and the last frost is September 28 and May 5, the average frost-free period is 145 d. Among the 162 stations in Northeast China, there are 155 stations where the first frost date became later, and there are 160 stations where the last frost date became earlier, and there are 158 stations where the frost-free period had been prolonged during the past 53 years. The first frost date has significantly delayed at the rate of 1.55 d/10 a, the last frost date has moved up at the rate of 2.51 d/10 a, and the frost-free period has prolonged at the rate of 4.08 d/10 a over the past 53 years. The changing characteristics of the frost reflects the climate warming (0.3 ℃/10 a). Along with the increase of the latitude and the altitude, the first frost date became earlier, the last frost date became later and frost-free period became shorter. The influence of the minimum temperature is bigger than the influence of average temperature. The first frost date, the last frost date and frost-free period had abrupt change in 1986, 1989 and 1986, respectively. The mutation of the frost in the three provinces all occurred in the 1980s and 1990s. After the mutation, the multi-year average contours of the first frost date, the last frost date and the frost-free period in the Northeast China all pushed northward.