关键词: 极端降水, 气候变化, 天山, 阿克苏

Abstract:

Based on the day-to-day observed data of precipitation from 55 meteorological stations in Xinjiang from 1961 to 2000, the climatic variations, tendencies and distribution of extreme precipitation have been analyzed during the last 40 years. The climate jumps have been examined in terms of 3-year moving averaged seasonal and annual series of extreme rainfall and frequency using Yamamoto method and Mann-Kendall method. Regional ecological environments have been changed tremendously after large-scale reclamation since the 1950s at the northern foot of the Tianshan Mountains and Aksu area. Rainfall and frequency of extreme precipitation have an increasing tendency in the two areas since the 1980s. Under the special geographical conditions and climate background, the changes resulted from variations of regional eco-environments and climate are induced by human activities. The results obtained are as follows: Quantity and frequency of extreme precipitation have an obvious increasing tendency at the northern foot of the Tianshan Mountains and Aksu area, especially since the 1980s, there is a climate jump of annual extreme precipitation in 1980; the linear tendencies of annual extreme precipitation are 24.5%/10a in Aksu area, 19.5%/10a at the northern foot of the Tianshan Mountains; the linear tendency of frequency increases by 20%/10a in Aksu area, and 14.5%/10a at the northern foot of the Tianshan Mountains. In other areas there are no obvious variations. Climate change of extreme precipitation is from variation of extreme rainfall in summer. The percentage that extreme precipitation takes up in annual precipitation: the Tianshan Mountions is 41.9%, northern Xinjiang and Hotan region are 17.2% and 1.9% respectively, the other areas are 25%-31.3%.

Key words: extreme precipitation, climate change, Tianshan Mountions, Aksu