VARIATION OF SPRING CLIMATE IN LOWER-MIDDLE YANGTZE-RIVER VALLEY AND ITS RELATION WITH SOLAR-CYCLE LENGTH

The relatively large number of historical records originating from the area of the Middle and Lower Yangtse River Valley in the late Ming dynasty and the Qing dynasty allows an estimation of the long term fluctuations of phenological dates. Dates of blossoming of plants, found in personal diaries and other documents, and used in this reconstruction are available, with some gaps, for 1580-1920. Independent estimates of spring conditions during the 18th century using data on last day of snowfall, and during 20th and late 19th centuries using accumulated temperatures in Shanghai are also presented. The results show that the spring weather in this region was colder than present in the 17th century and during 1790-1820 and 1870-1920. Spring temperature warmer than the present prevailed during 1720-1770 and 1840-1860. This variation agrees in its broad outline with that of the solar cycle length presented by Friis-Christensen and Lassen (1991).