近300a来古里雅冰芯记录的气候突变事件

根据古里雅冰芯高分辨率气候环境信息记录,利用小波气候突变的检测方法,对近300a来的气候突变事件进行了检测.结果表明,在百年尺度上,近300a来古里雅冰芯中所记录的δ¹⁸O(温度代用指标)发生了2次突变,分别在1788年和1932年;净积累量(降水量的代用指标)也发生了2次突变,分别在1805年和1939年;降水突变发生的时间迟于温度突变发生的时间.时间尺度越短,发生突变的次数则越多,这也体现了气候变化的层次性.因此,较好地确定隐含在气候资料中冷暖(干湿)期突变的位置,从冷暖(干湿)期的变更上去把握气候变化,将有助于认识气候变化的机理.

Abrupt Climate Change Events Recorded in the Guliya Ice Core in the Past 300 Years

Due to the climate variations with hiberarchy, climate data contains multi-scales variation signals. The warm or cold period is relatively existed. The longer time scale warm or cold period contains middle time scale warm or cold period. Meanwhile, the middle warm or cold period contains smaller time scale warm or cold period. Thus, the concept of "climate is becoming warmer now" or "climate is becoming colder now" is improper. For the multi-scale system such as climate system, the proper concept should be "in what a time scale, the climate is becoming warmer (or colder)". Precondition here must be in which time scale. The transition of the cold and warm periods showed the regulation of the climate variations. So, properly determining the abrupt climate change position which hidden in climate data and recognizing the climate variation in the view of the transition of the warm and cold periods, will be benefit to understand the mechanism of climate variations. This will be useful to reveal the self-resemble structure of the climate system. Analyzing the hiberarchy contained in climate data and anatomizing the interaction among different levels as well as the transition between different conditions in the same level will be in favor of predicting the abrupt change years of the cold or warm climate. This will also be the good foundation for predicting climate changes. Based on the high-resolution climate records recovered from the Guliya ice core, the abrupt climate changes in the past 300 a were detected using wavelet method. The result showed that, in 100 a time-scale, two abrupt climate changes were detected for δ¹⁸O (proxy index for temperature). The abrupt years is 1788 and 1932, respectively. There are also two abrupt climate changes for net accumulation in 100 a time-scale, corresponding to the years of 1805 and 1939. The occurrence of the abrupt climate changes for net accumulation (precipitation) was lagged behind that of temperature. The shorter time-scale, the more abrupt changes occurred, demonstrating the stratification of climate variations. Therefore, better detecting the years of the abrupt changes implied in climate archives and then understanding the climate changes in the view of transition of the warm/cold (dry/wet) periods would be benefit for understanding the mechanism of climate changes.However, in the 100 a scale, the net accumulation recorded in the Guliya ice core suddenly increased from 1939. Whether this corresponded with the suddenly strong of the southern Asian monsoon still needs to study further. Meanwhile, other researchers pointed out that a large-scale abrupt change of the Southern Hemisphere temperature occurred in 1939. Whether this is also demonstrated that, in some extent, the climate information recorded in the Guliya ice core can reveal the climate changes in Southern Hemisphere, which still needs more work to verify.