基于EEMD方法的区域降水事件特征分析——以京津冀地区为例

Characteristics of Regional Precipitation Events Using EEMD Method:A Case Study of Beijing-Tianjin-Hebei Region

区域降水事件特征影响水循环,进而对社会经济各个方面有着深远的影响。京津冀地区是我国的政治、经济、文化中心,水旱灾害频发,亟需全面了解该地区区域降水事件特征。以京津冀地区173个气象站1989—2018年间逐日降水数据为基础,共识别出552次区域降水事件,采用集合经验模态分解(EEMD)等方法,从持续时间、覆盖范围、降水强度3个要素对京津冀地区区域降水事件特征及时空分布情况展开研究。结果表明:①区域降水事件发生频率有随持续时间、覆盖范围增大而减小的趋势,减小趋势逐渐变缓,区域降水事件的降水强度在10 mm附近频率最高,区域降水事件的3个要素均与综合性强度有着明显的正相关关系;②京津冀地区区域降水事件综合性强度年际变化呈现出10 a左右的周期,但长期趋势性不明显;③京津冀地区区域降水事件沿地形呈“西北少、中部多”的空间分布规律。研究成果可为当地水资源规划、防灾减灾等提供技术支撑。

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.