Abstract: Based on the daily precipitation data from 19 stations in Shaanxi Province during 1960-2011, and by using the methods of inverse distance weighted interpolation, climate tendency coefficient, MK mutations inspection, Morlet wavelet analysis, correlation analysis, synthetic analysis, and R/S analysis, this paper analyzed the variation characteristics of intraannual precipitation concentration degree and concentration period and their variation tendency in the Province. In 1960-2011, the intraannual precipitation concentration degree in the Province ranged from 0.44 to 0.66, and presented the spatial distribution characteristics of being higher in the south and north but lower in the middle part. The intraannual precipitation concentration period ranged from 18.32-22.37 ten days, and showed comparatively small regional difference. The intraannual precipitation concentration degree presented an increasing trend, while the intra-annual precipitation concentration period displayed an advanced tendency. The variation trends of the intra-precipitation concentration degree and concentration period all existed obvious regional differences. A decreasing abrupt variation in the intraannual precipitation concentration degree occurred in 1974, while the postponed abrupt variation of the intra-annual precipitation concentration period happened in 1962. The variations of the intra-annual precipitation concentration degree and concentration period did not have a fixed cycle, but various cycle scales nested each other, showing stronger partial characteristics of time and frequency. In the whole province, the annual precipitation was positively correlated with intra-annual precipitation concentration degree, and also, positively correlated with intra-annual precipitation concentration period except in Hengshan of northern Shaanxi. Both in waterish and in water deficient years, the spatial distribution of intra-annual precipitation concentration degree displayed the characteristics of being higher in the south and north but lower in the middle part, while the spatial distribution of intra-annual precipitation concentration period had a greater difference. The variation tendency of the intra-annual precipitation concentration degree and concentration period in the future would keep the same with that in the past 52 years.

Key words: carbon stock, net primary productivity,