青藏铁路沿线永冻土区近千年的气候演变特征

利用树木年轮重建了青藏铁路沿线多年冻土区的年平均气温(763—1998年)、年降水序列(1518—1983年)。利用小波分析，发现10年时间尺度上气温可分为14个暖期和13个冷期，在30年时间尺度上中世纪暖期和小冰期表现明显；降水从30年左右时间尺度上看，大致上只有1591—1640年、1671—1730年和1770—1950年降水偏多，其余时间降水都偏少。现今依然处在暖干期。功率谱分析发现，气温主要周期为2．0，2．5，3．6，7．2，22．8和117．7年，降水主要周期为2．1，3．1，4．5，7．7，11．3，20．8，28和62年。

Characteristics of Climatic Evolution in Recent 1000 Years of Permafrost Region along Qinghai-Xizang Railway

Using the tree ring, the annual average air temperature (1763_1998) and annual precipitation sequence (1518_1983) of permafrost region along Qinghai-Xizang Railway are reestablished, the air temperature on 10 year time scale can be divided into 14 warm periods and 13 cold periods by waveletanalysis, and the Medieval mild phase and little ice age on 30 year time scale are significant. From30 year time scale, the precipitation in 1591_1640, 1671_1730, 1770_1950 are more than normal, in rest of years vice versa. Now it is stillin warm and dry periods. It is found by power spectrum that the main periods of air temperature are 2.0, 2.5, 3.6, 7.2, 2.8 and 117.7 years, while the main periods of precipitation are 2.1, 3.1, 4.5, 7.7, 11.3, 20.8, 28, 62 years, respectively.