中国极端干旱事件的年代际变化及其成因

研究了河北山西、黄河中下游、江淮和西北东部地区531年极端干旱事件的概率，采用古里雅冰芯δ¹⁸O含量和500年来太平洋年代际涛动指数进行了对比分析.Morlet小波分析发现四个地区的极端干旱事件概率和古里雅冰芯δ¹⁸O含量都存在着350年左右的准周期，且四个地区近500年来极端干旱事件概率的变化与古里雅冰芯δ¹⁸O含量的变化相反，在δ¹⁸O含量较高的时期，发生极端干旱事件的概率较低，反之亦然.对太平洋年代际涛动指数进行小波变换，发现80年尺度的准周期在逐渐衰弱而50年尺度的准周期却在逐渐增强.在80年或50年尺度的准周期处于控制地位时，四个地区处于极端干旱事件多发期，而在二者处于交替时期，即二者周期性均较弱的时期，处于极端干旱事件偏少期. 关键词： 干旱 冰芯 太平洋年代际涛动

The decadal variability and its cause of the extreme drought in china

This paper investigates the probability of extreme drought in four regions of China during the 1470—2000 A.D., and analyzes the δ¹⁸O record in Guliya ice core. By wavelet analysis, we find that the probability of drought in the four regions has the quasi-cycle of 350a, like the δ¹⁸O record in Guliya ice core. When the δ¹⁸O record is high, the temperature of Qinghai-Xizang Plateau is high too, and the probability of drought is low, and vice versa. This paper also analyzes the Pacific decadal oscillation and finds the quasi-cycle of 80a is weakening but the quasi-cycle of 50a is enhancing. When either of them is strong, the probability of drought is high, and the probability is low when the two quasi-cycles are alternating.