近40年甘肃河东地区大范围霜冻变化特征

目的]研究近40年甘肃河东地区大范围霜冻的变化特征。方法]利用1969～2008年甘肃河东地区分布较为均匀的15个站点的逐日最低温度资料,根据通用的霜冻气候统计指标,分析了近40年甘肃河东地区大范围霜冻及大范围连续性霜冻的变化特征。结果]自20世纪90年代起,甘肃河东地区平均终霜冻日期明显提早,初霜冻日期开始明显推迟,终霜冻日期提早时间明显比初霜冻日期推迟时间长;平均无霜冻期也明显延长。极早初霜冻日与极晚终霜冻日多发生于70、80年代,而极晚初霜冻日与极早终霜冻日则多发生于90年代中期以后;极长无霜冻期则逐渐变为频繁出现。40年来,连续性霜冻在逐渐减少,且强度也在降低。结论]该研究有助于了解甘肃河东地区霜冻气候和气候变化特征,对提高该地区异常霜冻灾害的预测能力、有效防御霜冻灾害、提高农作物产量具有重要的现实指导意义。

Variation Characteristics of Large-scale Frost in the East Region of the Yellow River of Gansu in Recent 40 Years

Objective] The research aimed to study variation characteristics of large-scale frost in the east region of the Yellow River of Gansu in recent 40 years.Method] Based on the daily minimum temperature data at 15 meteorological stations over the east region of the Yellow River of Gansu from 1969 to 2008,according to the common climatic statistical index of frost,the variation characteristics of large-scale frost and continuous frost in the east region of the Yellow River of Gansu in recent 40 years were studied.Result] Since the 1990s,the average last frost date in the east region of the Yellow River of Gansu was obviously ahead of time,and the first frost date started to obviously postpone.The advancing time of last frost date was longer than the postponing time of first frost date.The average frost-free period also obviously prolonged.The extremely early first frost date and extremely late last frost date mainly happened in the 1970s and the 1980s.The extremely late first frost date and extremely early last frost date mainly happened after the middle period of the 1990s.The extremely long frost-free period gradually started to appear frequently.In recent 40 years,the continuous frost was gradually reducing,and the strength was also declining.Conclusion] The research was favorable for understanding frost climate and climatic change characteristics in the east region of the Yellow River of Gansu,and had important guidance significance for improving prediction capability of abnormal frost disaster,effectively preventing frost disaster and improving crop yield in the area.