摘要
从极端事件再现时间的角度研究了中国极端高、低温事件再现时间序列的长程相关性、群发性以及二者的关系。发现极端温度事件再现时间序列具有长程相关性,表征长程相关性的标度指数分布存在着明显的区域性特征,并与大气环流有关,当中国大陆在盛夏或隆冬稳定的西风环流控制下,极端温度的长程相关性较好,标度指数较大。通过定义极端事件的群发指数,对极端高、低温进行研究,发现具有长程相关性再现时间序列的极端温度呈现群发现象,且极端温度再现时间序列的标度指数和群发指数二者在空间分布上有较好的对应,极端温度再现时间序列的长程相关性可能是导致极端温度群发性的原因。从年际变化的角度看,极端高温Ⅰ级群发区域的群发指数增长趋于平缓,而极端低温Ⅰ级群发区域的群发指数有下降趋势,这与近几十年来全球变暖一致。在年代际尺度上,群发指数分布的演变特征明显,极端高温Ⅰ级群发区域总体面积变化不大,而极端低温Ⅰ级群发区域面积明显减少。因此,极端低温事件群发性减弱很可能是年代际气候变暖的主要原因。
In view of return intervals, we studied the long range correlation of extreme high temperature and low temperature in China and its relationship with group-occurring. It is found that the time series of extreme temperatures shows a long range correlation and the scaling exponent, which means the significance of long range correlation, is related to the atmospheric circulation. When the China's Mainland is under the control of a stable westerly circulation （e. g. in winter and summer）, the temperature shows significant long range correlation, i.e. a greater scaling exponent, and the reconstructed events are usually group occurring. The group-occurring of the return intervals of extreme events is defined in this paper according to this character. Through the study of extreme high and low temperatures, we found that when a time series shows a long-range correlation, its extreme temperature events show a group-occurring phenomenon. The scaling exponent of the original temperature has a better correspondence in spatial distribution to the group-occuring index of extreme temperatures. And the long range correlation of time series may be the fundamental reason of group-occurring of extreme events. From the perspective of inter-annual change, the growth of group-occurring index of extreme high temperature＇s level-I region tended to moderate, while that of the extreme low temperature＇s tended downward. This is consistent with global warming in recent decades. And in the decadal time scales, the evolution characteristics of the group-occurring indexes distribution is apparent. The overall area change was not obvious as to the extreme high temperature＇s level-Ⅰ group-occurring region, but the area of the extreme low temperature＇s level- Ⅰ group-occurring region reduced significantly. Therefore, the weakening of extreme low temperature events＇ group-occurring is very likely to contribute to the inter-decadal climate warming.
出处
《气象学报》
CSCD
北大核心
2012年第2期302-310,共9页
Acta Meteorologica Sinica
基金
全球变化重大研究计划(2012CB955902)
国家自然科学基金(40875040
41005043)
国家科技支撑计划(2007BAC29B01
2009BAC51B04)
关键词
极端温度
再现时间
长程相关性
群发性
Extreme temperatures, Return intervals, Long range correlation, Group-occurring
