Abstract:

Based on the daily precipitation data of 17 ground meteorological stations in Shijiazhuang of Hebei Province from 1972 to 2014, the temporal and spatial variation characteristics of extreme precipitation indices were quantitatively analyzed by using RClimDex model and ensemble empirical mode decomposition (EEMD) method. The results show that the frequency of extreme precipitation event in Shijiazhuang of Hebei changed gently during 1972-2014, and the inter-annual fluctuation was great. The intrinsic mode function (IMF) component of six extreme precipitation indices by EEMD in Shijiazhuang showed quasi-periodic changes of 2.69-3.07 a, 5.38-6.14 a, 8.6-10.75 a and 21.28-35.63 a, in turn, and the variance contribution rate of IMF1 was the biggest. In spatial distribution, the extreme precipitation days (R25), maximum 5-day precipitation amount (RX5day), extreme precipitation (R95P) and consecutive wet index (CWD) were high in the west and low in the east. However, the simple daily intensity index (SDII) and consecutive dry index (CDD) showed opposite spatial pattern. In the past 43 years, the southwest vortex, westerly trough and typhoon were the main weather systems causing the heavy precipitation with long duration, high intensity and wide range in Shijiazhuang of Hebei, which was easy to cause disasters.

Key words: RClimDex model, extreme precipitation, EEMD, Shijiazhuang

摘要：

利用1972—2014年石家庄市17个地面气象站逐日降水数据，基于RClimDex模型和集合经验模态分解（EEMD），定量分析该区域极端降水指数的时空变化特征。结果表明：近43 a石家庄市极端降水事件发生频率总体变化趋势平缓，但年际间波动较大；经EEMD得出的6项极端降水指数的4个固有模态函数（IMF1、IMF2、IMF3、IMF4）分量，分别表现出2.69～3.07 a、5.38～6.14 a、8.60～10.75 a和21.28～35.63 a的准周期变化；在空间分布上，R25、RX5day、R95P和CWD极端降水指数呈西高东低的空间格局，而SDII和CDD则相反，表现出东高西低的空间特征。近43 a来西南涡型、西来槽型和台风型3种类型是造成石家庄市强降水过程的主要天气系统，造成的降水持续时间长、强度大、范围广，易致灾。

关键词: RClimDex模型, 极端降水, EEMD, 石家庄