ANNUAL DISTRIBUTION FEATURES OF PRECIPITATION IN CHINA AND THEIR INTERANNUAL VARIATIONS

The hierarchy and definition of the precipitation-concentration degree and precipitation-concentration period of annual precipitation have been proposed by using the so-called vectormethod of annual distribution of precipitation,so that the two relevant parameters can representthe annual distribution of total precipitation correctly and indeed accurately.The relationshipbetween the spatial and temporal distribution patterns and variations of the two parameters and theannual precipitation amount in China has been further investigated.Results demonstrate that theprecipitation-concentration degree and the precipitation-concentration period increase fromsoutheast to northwest gradually.Moreover there obviously exists a belt pattern:the largestvariability of the precipitation-concentration degree and the precipitation-concentration periodoccurs in the Yellow River Valley and the middle and lower reaches of the Yangtze River,corresponding to the significant zones in which flood and drought take place frequently.It is foundthat there exist high correlations between the precipitation-concentration degree and precipitation-concentration period and the annual precipitation amount in Northeast China,North China,themiddle and lower reaches of the Yangtze River.Furthermore,8-year and 22-year periodic oscillations in the precipitation-concentration degreeand 6-year and 12-year cycles in the precipitation-concentration period are identified by use of theirMorlet wavelet analysis.