近300年来中国西部气候的干湿变化

利用冰川积累量和树木年轮代用资料，分析了中国西部地区近300年来气候干湿变化的时空特征。中国西部气候干湿变化存在显著的准70年尺度的周期变化。准30年和准110年尺度的周期变化在大部分地区也较显著。在准70年尺度的干湿变化中，1850年前，高原东部和新疆在干湿变化上基本同步，可划分到一个湿度带中，这就和高原西部有了一种偶极子的位相关系。在1850年后，这种位相型有些变化，新疆渐渐的和高原西部的位相趋于一致，但这个同位相关系不如1850年前新疆和高原东部的同位相关系那么好。这时候应该重新把高原西部和新疆划分到一个湿度带中，高原东部作为另一个湿度带，两者之间成为一种偶极子的关系。在最近十几年，似乎高原东西部又合为一个湿度带，而与新疆成偶极子的关系。但由于小波分析所固有的边界效应的影响，这一可靠性是值得怀疑，不过这三者之间两两组合的偶极子关系的漂移倒是一个有意思的研究方面。110年尺度的干湿变化中，青藏高原主体部分及华山地区为一个干湿分布一致的湿度带。1850年以前整个高原和新疆地区在准110年尺度上存在着比较一致的干湿变化，而19世纪末期突变发生后，高原北部和新疆地区的干湿变化存在偶极子的位相关系。在准30年时间尺度的干湿变化中，高原和新疆地区的干湿变化基本一致。

Dry and Wet Climatic Changes of Western China in Recent 300 Years

The ice core and the tree ring proxy data are employed to analyze the temporal and spacial characteristics of dry and wet climatic changes in western China in recent 300 years. The results show that in whole western China, the dry and wet climatic changes appear a significant quasi\|70 year period changes. In most of the region, the quasi\|30 and quasi\|110 year periods are fairly significant as well. Before the year 1850 and according to the quasi\|70 year period, the eastern part of the Tibet Plateau and Xinjiang region almost are in the same dry and wet phases. They can be classified into one humidity belt. Namely both humidity belts, the Xinjiang and the western part of the Plateau, have a dipole relationship. But after that year, the Xinjiang changes gradually into the simultaneous phase with the western part of the Plateau, but it is not as good as the relationship between Xinjiang and the eastern part of the Plateau again yet. In other words after the year 1850, the western part of the Plateau and Xinjiang are grouped into the same humidity belt, not the eastern part of the Plateau again, now both the west and east of Xinjiang construct a new dipole. Up to recent decade, it is likely to appear that the western and eastern parts of the Plateau change into a simultaneous phase and a new dipole is constructed with Xinjiang. But because of the boundary effects of the wavelet transform, the reliability can be doubted. Anyhow, the drift of the dipole relationship among above three regions is very interesting, it is likely the drift of climate. In the situation of quasi\|110 year change, the main part of the Plateau and the Hua mountain compose one humidity belt, before the year 1850 period, the Plateau and Xinjiang take fairly the same phase; after the climatic abrupt change of the end of 19th century, the north part of the Plateau and Xinjiang show a relationship of dipole. on quasi\|30 year period scale, the phase of the Plateau and Xinjiang are almost identical.