The response of climatic jump in summer in North China to global warming

To reveal climatic variation over North China, the climatic jump in summer in Beijing are analyzed using the data of precipitation of summer (June. July, August) during the period of 1841-1993, in which those missed before 1950 were reconstructed by the stepwise regression method with minimum forecast error. The climatic jumps at different scales are analyzed using different diagnostic methods with different decade (10-100 years) windows. Some new methods and ideas are proposed. The variance difference. the linear tendency difference, and the difference of power spectral distribution between the samples before and after the period at the moving point in the center of the series are compared with other methods (fbr example, Mann-Kendall test, t-test, and accumulative anomaly etc.). Considering the differences among the statistics above, a synthetic jump index is also proposed in order to get the definite jump points in the moving series. The results show that the climatic jumps in the area occurred in the 1890s. the 1910s and the 1920s, and mostly in the 1920s, which suggests that the local climatic: jumps in North China have I simultaneous response to the global warming in the hundred-year scales.