关键词: 天山山区, 气候变化, 树木年轮, 降水, 趋势预测

Abstract:

Four reconstructed precipitation sequences and their relations responding to precipitation variation of ten weather stations in Tianshan mountainous area are applied to reconstruct the precipitation sequence in recent 235 years in Tianshan mountainous area. The explained variance of reconstructed sequence can reach up to 47.7%. The analyses on the precipitation change characters in recent 235 years in Tianshan mountainous area disclose that the 235-year precipitation process can be interpreted as 7 wet periods and 7 dry periods, totaling up to 124 years wet-year and 111 years dry-year. The reconstructed precipitation sequence shows remarkable high-frequency change cycles of 2.1 years, 3.0 years, 5.8 years, and 6.0 years, also a low-frequency change cycle of 24 to 25 years. Over the past one hundred years, the precipitation change in Tianshan mountainous area can be divided into two stages: from early 1900's to 1980's, precipitation gradually reduced, glaciers retreated, river runoff decreased, lake shrank, desert area increased and vegetation cover reduced; from late 1980's on, precipitation rapidly increased, consequently river runoff and lake area increased, sandstorm frequency reduced, the ecological environment improved, but simultaneously floods and geologic disasters frequently broke out. By the cycle superposition method that based on the variance analysis it is predicted that the climate change in future 23 years in Tianshan mountains area will be characterized by humid feature, totaling 14 years or 61 percent, possibly there will be several more drought years than the normal.

Key words: Tianshan mountainous area, climate change, tree-ring, precipitation, trend prediction