关键词: 陕西, 暴雨, 基本特征, 评估方法

Abstract: Applying the observation data of daily precipitation from 78 weather stations during the years of 1961- 2012，the spatial-temporal distributions and climatic characteristics of the rainstorms in Shaanxi Province are analyzed by the linear trend analyses，the Mann-Kendall analyses and the power spectrum methods. To conduct the in-time evaluation on the rainstorm events，the assessment method for the daily rainstorm events for each station and the synthesized index for each procedure are established，based on this，the rainstorm procedures in 2011-2012 are further tried to be assessed. The results show that the rainstorms are primarily concentrated in the July-August-September，which accounts for about 79% of the total year in frequency. Over Shaanbei and Guanzhong，a single peak is found respectively in July and August in the frequencies while in Shaannan it shows two peaks in July and late-August-early-September. The regions with maximal frequencies and intensities are the Shaannan，the western Guanzhong，and the eastern Shaanbei，respectively. The rainstorm frequencies are 1-5 d/a in Shaannan and 0.7-1 d/a in the western Guanzhong and the eastern Shaanbei. And the intensity usually reaches approximately 67-80 mm/d. In recent years，the rainstorm frequencies are significantly increased，by a rate of 5.4 times/a in Shaanxi，especially over Guanzhong and the central-eastern part of Shaannan. The frequencies have quasi-periods of 2 and 6 a in Shaanbei，2-4 a in Guanzhong，and 2-3 a in Shaannan，respectively. The intensities of rainstorm are enhanced over the whole province with the most remarkable regions of western Guanzhong and eastern Shaanbei. In particular，the rainstorm intensity in Guanzhong emerges a abrupt change around 1985. For the rainstorm evaluation，the daily rainstorms and the procedures for each station are both classified into 4 levels by the frequencies of 50%，30%，15% and 5%，respectively. The method by ranking and ordering and procedure index are feasible and practical，satisfying the requirement of the in-time evaluation services for rainstorm events.

Key words: Shaanxi Province, rainstorm, climatic characteristic, evaluation method