Reconstruction and Discussion of 314 a Precipitation in Yili Prefecture, Western Tianshan Mountains
YUAN Yu-jiang 1 , YE Wei 2 , DONG Guang-rong 3 (1.Xinjiang Institute of Meteorology, Urumqi Xinjiang 830002, China; 2.Xinjiang Institute of Ecology and Geography, CAS, UrumqiXinjiang 830011, China; 3.Cold and Arid Regions Environmental
Single correlation screen indicated that the correlations were significant among 10 tree-ring chronologies and precipitation from June in the last year to May in the current year, and the maximum correlation coefficient was 0.584 (α=0.005). Using 5 tree-ring chronology series, the 314 a precipitation was well reconstructed and its explain variance was 75%. It is verified that the reconstructed precipitation was more reliable. Several conclusions obtained by analyzing the precipitation sequence reconstructed are as follows: 1) In the recent 314 a, the precipitation reconstructed has 4 wet periods above its mean and 4 dry periods bellow its mean. The wet periods were corresponding to the wet periods of annual precipitation reconstructed in the Northern Xinjiang, and the cold periods in former USSR. North and East China and in the Qilian Mountains. 2) Correlation analysis shows that the precipitation series reconstructed in the Yili Prefecture is well representative of precipitation change in the Northern Xinjiang and in the Southeastern Kazakhstan. 3) The corresponding ratio of wet-dry year between the Yili Prefecture and the Southeastern Kazakhstan is about 68%. 4) The long-term precipitation series reconstructed in the Yili Prefecture has significant change periods of 150, 29, 17, 23 and 60 a, and occurred abrupt changes in 1757, 1778, 1892 and 1927. The abrupt changes in 1892 and 1927 were corresponding to the temperature abrupt changes in North Hemisphere and the globe, but the response of precipitation in the Yili Prefecture to the temperature abrupt changes in the globe was complicated. 5) In the 314 a precipitation reconstructed in the Yili Prefecture, wet year accounted for 9.6%, drought year 6.0%, partial wet year 19.7%, partial drought year 29.3%, and normal year 35.4%. The maximum precipitation (585.1 mm) occurred in 1813, which was 66.9% more than the long-term mean, and the minimum precipitation (177.3 mm) occurred in 1693, which was 49.4% less than the long-term mean. 6) It is expected that the change trend of precipitation in the Yili Prefecture is manly near or above its mean from 1996 to 2002, near or bellow its mean during 2003～2015, after that, precipitation go into a stage mainly near or above its mean.