中文摘要：

作为冬季寒冷程度的指标之一，负积温的变动在理论上可能与冻土发育程度有一定的关系。选用EOF分解、连续小波变换等方法对东北地区81个气象站点1957-2007年的负积温进行分析，以探究其变化的时间序列及空间分异规律，及其与冻土退化、平均温变化间的关系。结果表明，东北地区负积温呈全区一致性上升趋势，且增温率由西南向东北递增。全区经历明显的降温-增温-降温阶段，大兴安岭地区、小兴安岭北部及以北地区高温期短、振幅较大，年际变差更明显。除黑龙江北部、内蒙古东部以外，全区负积温最低、最高及突变年份一致，表现出全球气候变化下负积温变动的区域同步性。负积温增温与冻土退化及年平均温度的上升具有较良好的一致性。

英文摘要：

The negative accumulated temperature is an index of cold degree in winter. Theoretically, its change associates with permafrost development. In this paper, empirical orthogonal function, wavelet transform, as well as cluster analysis, are used to analyze the negative accumulated temperature in Northeast China, aiming to explore the spatial and temporal variations of negative accumulated temperature, to acquire its relation with permafrost degeneration and annual mean temperature change. The results showed that from 1957 to 2007, the negative accumulated temperature in Northeast China, which was calculated from 81 meteorological observation stations, had increased. The increase rate during the 51 years had decreased progressively from northeast to southwest of the study area. From 1957 through 2007, the study area can be divided into three periods according to the negative accumulated temperature, i.e., cold, warm and cold periods. In the Da Hinggan Mountains and the northern Xiao Hinggan Mountains, The warm periods were shorter, with large annual and interannual amplitudes of vibration. Except in north of Heilongjiang Province and east of Inner Mongolia Autonomous Region, the lowest, highest and mutation years of negative accumulated temperature were the same, which indicated the regional synchronization of accumulated temperature change. The increase of negative accumulated temperature was in accordance with permafrost degradation and the increase in annual mean temperature.