1960-2012年中国东部冬季风时期极端降温事件的时空特征

利用1960-2013年中国753个站逐日日平均气温资料，对中国东部冬季风时期极端降温事件进行了定义，并研究了近53 a中国东部冬季风时期极端降温事件的时空特征。结果发现，极端降温事件发生最频繁的地区位于东北南部、华北大部分地区和华中北部，华中南部则较少发生。过去的53个冬季风时期，中国东部极端降温事件普遍减少，且东北南部、华北南部和东部、华中北部以及华东北部的减少趋势最为明显，减小幅度可达0.4~0.8次/（10 a）。此外，东北、华北和华中的极端降温事件发生频次分别在1980、1973、1969年出现了由多到少的突变。极端降温事件的强度也存在空间差异，其平均强度从北到南呈现出强-弱-较强的特点。

Temporal and spatial characteristics of extreme cooling events in eastern China in winter monsoon period during 1960 and 2012

Based on the daily mean temperature data from 753 stations in China during 1960 and 2013,the extreme cooling events in eastern China during winter monsoon period was defined and its temporal and spatial characteristics were studied.Results showed that extreme cooling events occurred most frequently in the south of Northeast China,most part of North China and the north of Middle China while it seldom occurred in the south of Middle China.In the past 53 winter monsoon periods,extreme cooling events in eastern China were generally decreasing and the decreasing trends were most obvious in the south of Northeast China,southern and eastern parts of North China,northern parts of Middle China and East China at a rate of 0.4-0.8 times per decade.In addition,the frequencies of extreme cooling events in Northeast China,North China,and Middle China experienced sudden decreases in 1980,1973 and 1969,respectively.A spatial difference in the average intensities of extreme cooling events was also found out with a strong-weak-strong pattern from north to south.These results are helpful to deepen our understanding of the characteristics of extreme cooling events in China in recent decades and to provide a scientific basis for decision-making of chilling injury prevention.