Abstract: This article aims to analyze the inhomogeneity characteristics of inter-annual precipitation on the Loess Plateau, and to provide reference for local vegetation construction and ecological recovery, rational use of water resources, and the prevention and control of soil and water loss. Precipitation concentration degree (PCD) and precipitation concentration period (PCP) were used to analyze the inhomogeneity characteristics of inter-annual precipitation and its trend in recent 50 years based on 51 meteorological stations of the Loess Plateau from 1959 to 2008, and EOF, correlation analysis and trend analysis were also employed. The results are shown as follows. (1) The annual precipitation of the Loess Plateau is between 50-850 mm, with a decreasing trend from southeast to northwest. (2) The PCD of the Loess Plateau region is between 0.53 and 0.75, which gradually increased from the southeast to the northwest, while the PCP is mainly observed in the mid- and late July. (3) In spatial distribution, PCD mainly manifests a north-south reverse pattern with a decreasing trend, while PCP consists of two main centers (east-west reverse and southwest and east-other areas reverse). (4) In terms of changing trend, the average trend coefficient of PCD on the Loess Plateau is 0.005, while that of PCP is -0.21. The regions with obviously increased PCD are mainly distributed in Ningxia and the Mount Wutai in Shanxi, and the areas with obviously decreased PCD include Yangquan of Shanxi and Menyuan of Qinghai, while PCP shows a decreasing trend in most parts of the Loess Plateau. (5) PCD shows a positive correlation with annual precipitation, most of which has passed the significant level 0.05, while PCP has a slight correlation with precipitation, the places that has passed the significant level 0.05 are only distributed in Xingxian of Shanxi, Luochuan of Shaanxi and Guyuan of Ningxia.

Key words: Loess Plateau, precipitation concentration degree(PCD), precipitation concentration period (PCP), spatiotemporal change