清代中后期江苏四季降水变化与极端降水异常事件

根据清代雨雪档案记载,重建了1736～1908年江苏6个府的逐季降水等级序列。分析发现:（1）1750s、1790s、1830s、1840s及1880s等5个年代江苏全省春、夏多雨,1770s、1780s、1810s及1870s等年代则春、夏少雨;秋季降水1750s、1840s、1850s及1860s等4个年代通省偏多,1770s、1810s及1890s等则偏少;冬季降水1830s、1840s及1890s等3个年代通省偏多;1820s、1850s及1870s等3个年代降水偏少。（2）1755年、1823年、1840年、1849年、1883年、1885年和1906年等7年江苏出现极端大涝;1768年、1778年、1785年、1814年、1856年、1873年、1876年和1891年等8年则极端亢旱。（3）江苏气候在1830年前后可能发生过一次转折。其中1830年以前降水变化相对和缓,多雨期和少雨期持续时间较长;而1830年以后,旱、涝时段频繁交替,且多发极端旱、涝事件。这一特点与El Nino事件在1830年以后相对多发相对应。

Variation of seasonal precipitation and extreme events in Jiangsu Province during 1736-1908

Based on the snow and rainfall archives in the Qing Dynasty, the seasonal precipitation grade series of 6 prefectures in Jiangsu province from 1736 to 1908 were established. Then the temporal and spatial patterns of the precipitation in Jiangsu province were analyzed and the extreme events in Jiangsu province from 1736 to 1908 were also identified. The results can be summarized as follows: (1) Although the interannual variations of precipitation for 6 prefectures are different, the interdecadal variations are similar except in a few decades. In Jiangsu province, it was rainy in spring and summer during the 1750s, 1790s, 1830s-1840s and 1880s, whereas it was rainless in the 1770s-1780s, 1810s and 1870s. The autumn precipitation in Jiangsu province was higher than the normal in the 1750s, 1840s-1850s and 1860s, but lower in the 1770s, 1810s and 1890s. The winter precipitation in the 1830s-1840s, and 1890s was relatively high, but it was relatively low in the 1820s, 1850s and 1870s. (2) From 1736 to 1908, there were 15 extreme events of flood or drought in Jiangsu province. In which 1755, 1823, 1840, 1849, 1883, 1885 and 1906 were extreme flood years; and 1768, 1778, 1785, 1814, 1856, 1873, 1876 and 1891 were extreme drought years. (3) There was probably an abrupt change of climate around 1830 in Jiangsu province. From 1736 to 1830, the climate was stable and the variation of precipitation was moderate. Whereas after 1830 the climate showed the instability, and the rainy and droughty periods alternated frequently with ano maly increased extreme events of flood or drought. A comparative analysis showed that the instability of climate was correspondent with the high frequency of E lNino after 1830. These results are not only important reference for the preci pitation projection in the future in Jiangsu province, but also great significance for the study on the long-term variations of East Asian Monsoon.