关键词: 区域降水事件, 持续时间, 覆盖范围, 降水强度, 时空变化, 集合经验模态分解, 京津冀地区

Abstract: Regional precipitation affects the water cycle and thus has a profound impact on various sectors of the social economy. The Beijing-Tianjin-Hebei region, as the political, economic and cultural center of China, suffers from frequent flood and drought disasters. Complete understanding of the precipitation characteristics of the region is in urgent need. A total of 552 regional precipitation events was identified from the daily precipitation data from 1989 to 2018 at 173 meteorological stations in Beijing-Tianjin-Hebei region. The Ensemble Empirical Mode Decomposition (EEMD) method was employed to examine the characteristics and temporal and spatial distributions of regional precipitation events in the region from three aspects: duration, coverage and precipitation intensity. Results unveiled that: 1) the frequency of precipitation events in Beijing-Tianjin-Hebei region displayed a trend of declining along with the elongation of duration and the expansion of coverage area; but such declining trend gradually alleviated. The intensity of regional precipitation events reached the highest frequency around 10 mm. Duration, coverage, and precipitation intensity all had obvious positive effect on the comprehensive intensity index. 2) The interannual change of comprehensive intensity of regional precipitation events in the Beijing-Tianjin-Hebei region presented a cycle of about 10 years; but the long-term trend was not insignificant. 3) Precipitation events distributed more in the middle while less in the northwest in the Beijing-Tianjin-Hebei region. The research findings offer support for the water resources planning and disaster prevention and reduction for the region.

Key words: regional precipitation event, duration, coverage, precipitation intensity, temporal and spatial changes, Ensemble Empirical Mode Decomposition, Beijing-Tianjin-Hebei region