VARIATION OF PRECIPITATION OVER CHINA IN THE PAST 100 YEARS
With the aid of the relationship found between the features of fields of precipitation anomalies in adjacent geographic regions, an interpolation model for precipitation of 42 stations in china is established in terms of the empirical orthogonal function. Evenly distributed, continuous sequences of precipitation in the period 1881—1981 are thus obtained. By solving the empirical orthogonal function for annual and seasonal precipitation departures, it is found that the alternative appearance of belts of positive and negative departures is the basic pattern for precipitation distribution in China.The principal components of annual and seasonal precipitation amounts for all 42 stations show no apparent long-term trend. Statistically significant periods foundby the analysis of variance spectrum are concentrated in the cycles of 35, 4.7 and 2 years.The cycle of approximately 4.7 years may be related to the Southern Oscillation. In addition,the amplitudes of mean precipitation departures are seemingly linked with the 11-year sunspot cycle.Near the year of maximum soiar activity, the frequency of drought or excessive rain increases notably.