1960-2009年中国冬季区域性极端低温事件的时空特征

Spatial/Temporal Characteristics of China Regional Extreme Low Temperature Events in Winter During 1960-2009

采用区域性极端低温事件客观识别技术对1960—2009年的区域性极端低温事件进行检测,并分析其空间分布和时间演变特征。结果表明:区域性极端低温事件指标中最低温度和几何中心纬度的频次分布为双峰特征,发生频次较高的纬度主要位于30°N和42°N附近,且1980年代中期以前南北两个带并存,之后则以30°N附近为主;1960—2009年事件的发生频次、强度和最大覆盖面积等呈总体减弱趋势,在1980年代后期存在显著的转折,1990年代后期变化逐渐趋于平缓,并且这种变化主要是由占总数10%的持续时间长和空间范围广的事件作用的结果。此外,对体现事件多方面影响的综合指标进行等级划分并分析其变化特征。

An objective identification technique was used to detect regional extreme low temperature event（RELTE） during 1960-2009,and the spatial distribution and temporal variation of the events were investigated.Results indicate that the probability distribution of the minimum temperature and the latitude of the geometrical center of RELTEs both obey the bimodal distribution.The center of RELTEs was mainly located in two latitude belts of nearly 30°N and 42°N.Before the middle 1980s,the south and north belts coexisted but the north belt weakened obviously since then.Besides,the annual accumulative values of the frequency,intensity and maximum covering area of RELTEs decreased overall during 1960-2009 and there was an obvious phase shift at the end of 1980s and the variation became flat after 1990s.These characters might result from the RELTEs with long duration and wide space range which accounted for 10% of all events.Further more,the integration index that reflects the overall influences of RELTEs were further investigated.