Abrupt Changes of Precipitation in Delingha Region, Qinghai for the Last 1000 Years
青海德令哈地区千年来降水量的突变分析

Based on the tree ring width chronologies developed in Delingha region, Qinghai province, the annual precipitation variations for the last 1000 years has been reconstructed recently. In this study, we investigate the abrupt changes of precipitation for the last 1000 years. Smoothing t-test and smoothing F-test methods were used to search for possible abrupt changes in the mean value and the standard deviations of 30-year climatic average precipitation. Significant abrupt changes were found during the last 1000 years and we suggested that solar activity played an important role in influencing these changes. It is evident that the precipitation decreased significantly during the periods of the Wolf, Spoerer, Maunder and Dalton minima of solar activity, and the t-test verified the existence of statistically significant differences within these periods. The time and the direction of abrupt changes of precipitation coincided well with the abnormal variations of solar activity. The abrupt changes of precipitation in Delingha may link with the interdecadal changes of East Asian Summer Monsoon for the last century. The time of abrupt changes in Delingha was ahead the time of abrupt changes in eastern China, which may be an important indicator for long-term change forecast of precipitation.