中文摘要：

利用临沧市气象局1961--2010年霜的地面气象观测资料，分析了临沧市近50年霜的气候变化特征，结果得出：近50年临沧平均初霜日为12月10日，终霜日为2月17H，无霜期为295d，霜日34d；20世纪60年代到90年代临沧初霜日正常，终霜日稍推后，无霜期略缩短，进入21世纪初，初霜日推后，终霜日提前，无霜期延长明显；近50年临沧初霜日推后6d，终霜日提前11d，无霜期延长15d；最短无霜期发生在20世纪90年代，最长无霜期发生在21世纪初。临沧市20世纪90年代中期是无霜期的一个突变点，从1995年开始无霜期从一个相对偏短期跃变为一个相对偏长期。

英文摘要：

Based on the meteorological data of frost in Lincang City during 1961--2010, this paper ana- lyzes the climate variation characteristics of frost. The result shows that over the past 50 years the average date of first frost is December 10 and the average date of last frost is February 17. The average frost-free pe- riod is 295 days and the frost period is 34 days. We can find that Lingcang＇s first frost date is normal from 1960s to 1990s, but the last frost date is getting Later and tt/e frost-free period gradually sho~,ens. In the 21st century, the first frost date is getting Later and the last frost date is moving ahead. Moreover the frost- free period extended obviously. In general, in the 50 years, the firsi frost date of Lincang delayed by 6 days, the last frost date moved ahead by 11 days, and the frost-free period extended by 15 days. The shor- test frost-free period appeared in the 1990s, and the longest one in the 21st century. The result shows that the mid-1990s was an abrupt change point of frost-free period in Lincang, and since 1995, the frost-free pe- riod jumped from a relatively short-term phenomenon to a realatively long-term phenomenon.