Centennial changes of drought/flood spatial pattern in eastern China for the last 2000 years

The statistical characteristics of the bicentennial changes of the drought/flood spatial pattern over the eastern part of China have been analyzed from 101 AD to 1900 AD, and their relationship with the cold/warm climatic variation in the same time span are discussed as well. The main conclusions are as follows. (I) During the period of the 2nd ～ 11th centuries, the spatial pattern of drought/flood in the eastern part of China was characterized by thc east-west differentiation. Namely, it was dry in the west (northwest) while it was wet in the east (southeast). (ii) From the 12th to 15th centuries, the east-west differentiation coexisted with the south-north differentiation, and the former was still the dominant pattern. (iii) However, the dominant spatial pattern changed to the south- north differentiation during the 16th ～ 19th centuries, namely, it was dry in the north and wet in the south. As for the dry-wet demarcation line. It shifted westward in warn times, and once reached Datong-Taiyuan-Xi' an-Hanzhong; whereas in cold times, it retreated southeastward and reached Ji' nan-Heze-Nanyang. Furthermore, the transmeridian (W-E) dry-wet demarcation line was replaced by the meridian (N-S) dry-wet demarcation line during the two coldest periods. Moreover, in cold times, it was dry in northern China, and it was wet in the middle and lower reaches of Changjiang River and regions south of Changjiang River; in warm times, however, it was wet in northern China, and was dry in eastern China, especially in the lower reaches of Changjiang River and regions south of Changjiang River.     

过去2000年中国温度变化研究的几个问题

根据最近重建的中国东部地区过去2000年冬半年温度距平序列,结合最近其他一些相关研究结果,对过去2000年中国温度变化序列的重建方法、小冰期及魏晋南北朝冷期的起迄时间与寒冷状况、中世纪暖期与隋唐暖期的温暖程度、过去2000年中国冷暖变化的幅度与速率、温度变化的千年波动周期、20世纪气候增暖是否超出过去2000年气候波动的最大范围及20世纪暖期历史相似型等几个问题进行了综合评述.     

过去2000 a中国东部干湿分异的百年际变化

分析了101～1900AD间中国东部每200a的干湿分异及其变化状况,讨论了它们与冷暖变化的对应关系.结果显示:2～11世纪,我国东部干湿分异为东西分异,西(西北)干东(东南)湿;12～15世纪,东西分异与南北分异并存,但仍以东西分异为主;而16～19世纪则为南北分异,北干南湿.冷暖变化与区域干湿变化的对应关系是:在暖的时期,干湿分界线偏西,最西达大同-太原-西安-汉中一线;在相对较冷的时期,干湿分界线摆向东南,达济南-菏泽-南阳一线,摆动最大幅度达5个经度以上;而在最冷的两个时段,东西分界线被南北分界线所取代.冷的时期,华北地区偏干,长江中下游及其以南地区偏湿;暖的时期,华北地区湿润,华东地区,特别是长江下游及其以南地区偏干.