1796—2015年成都雨季降水量序列重建与特征分析

Reconstruction and Analysis of Rainy Season Precipitation in Chengdu During 1796-2015

利用清代雨雪分寸记录和现代器测资料,重建了成都1796—2015年分辨率为年的雨季降水量序列。结果表明,过去220 a间成都的平均雨季降水量为838 mm,19世纪20~40年代、80年代到20世纪10年代、20世纪30~40年代降水偏多,19世纪初到20年代、50~70年代、20世纪20年代、50年代到21世纪初降水偏少,并在1879—1880年发生了由少到多的明显突变;降水最多的10 a为1832年、1896年、1898年、1899年、1903年、1907年、1915年、1921年、1937年和1947年,最少的10 a为1814年、1838年、1865年、1868年、1869年、1872年、1930年、1939年、1970年和2002年。成都雨季降水量存在显著的50~75 a周期,和太平洋年代际振荡(Pacific Decadal Oscillation,PDO)指数在50~70 a信号上存在较强的负相关,且与上一年冬季至当年秋季北印度洋的全球海表温度(SST)及当年夏秋季赤道太平洋的SST也存在较强的负相关,SST偏暖(冷)时,雨季降水量往往偏少(多)。

Chengdu(102°54′-104°53′E, 30°05′-31°26′N) is located in the region of southwest, and on the east edge of Tibetan Plateau, where the precipitation is affected by the South Asia monsoon and East Asia monsoon,and rainy season is concentrated from May to October. The meteorological observation was started from 1951,which is too short for revealing the decadal to centennial climate variation. Thus, it is important to reconstruct long-term precipitation series in Chengdu, and also it has great significance for not only recognizing teleconnections of precipitation with climatic modes, but also analyzing the long-term variation of Asian monsoon subsystems and their impacts on precipitation. There are abundant Yu(rainfall)-Xue(snowfall)-Fen(Chinese length unit, 0.32 cm)-Cun(10-Fen, 3.2 cm) archives reported to the Emperors by officials in the Qing Dynasty in Southwest China, which recorded precipitation dates or event frequencies in Chengdu in detail, providing important data for the reconstruction of the rainy season precipitation in Chengdu since the middle and late Qing Dynasty. Based on Yu-Xue-Fen-Cun archives and modern instrumental data, this paper reconstructed the rainy season(May to October) precipitation in Chengdu from 1 796 to 2015 with annual resolution, using the correlationship between monthly rainy days and precipitation. The results show that the average rainy season precipitation during the past 220 years in Chengdu is 838±99.3 mm(95% confidence interval). The precipitation is higher than normal in 1820 s-1840 s, 1880 s-1910 s, 1930 s-1940 s, and lower in 1800 s-1820 s, 1850 s-1870 s,1920 s, and 1950 s-2000 s, and there is an obvious abrupt change from less rainfall to more in 1879-1880. The ten years of 1832, 1896, 1898, 1899, 1903, 1907, 1915, 1921, 1937 and 1947 have highest precipitation, while1814, 1838, 1865, 1868, 1869, 1872, 1930, 1939, 1970 and 2002 have lowest precipitation. On the decadal time scale, the rapid increasing precipitation occurs at 1939-1948, and rapid decreasing precipitation occurs at 1829-1838. On the centennial time scale, the rapid increasing in 100-year occurs at 1808-1907 with a rate of 2.1 mm/a, and the rapid decreasing in 100-year occurs at 1896-1995 with a rate of-2.5 mm/a. The reconstructed series in Chengdu show significant oscillation signal with 50-75 a cycles, and has a strong negative correlation with PDO for 50-70 a cycle. It also has a strong negative correlation with SST of the northern Indian Ocean from the winter of the previous year to the autumn of the current year, and SST of the equatorial Pacific Ocean in the summer and autumn of the current year, which means warmer(colder) SST tended to link with less(more) rainy season precipitation.