基于EEMD的华北平原1901-2015年旱涝灾害分析

Analysis on drought and flood disasters in North China Plain from 1901 to 2015 based on EEMD

采用一种适用于非线性、非平稳序列的信号提取方法 -EEMD,基于1901-2015华北平原的266个格点的标准化降水蒸散指数,确定了旱涝灾害等级序列,分析了旱涝灾害演变的周期规律及旱涝等级频率的空间分布。结果表明:1)SPEI-12表征的旱涝灾害等级序列在1940年出现了突变,干旱灾害集中在1940年之前,洪涝灾害集中在1940年之后,年际尺度上存在平均周期为4年和8年的波动周期,年代际尺度上存在着13年、29年、46年的平均波动周期。2)极端干旱和极端洪涝分别发生556次和655次,分别占旱涝发生总次数的1. 76%和2. 08%,但总体干旱频率(19. 46%)明显高于洪涝频率(16. 43%),气候整体偏干。3) SPEI-3表征的旱涝灾害等级序列经EEMD分解后,春季1994年以后洪涝灾害等级逐渐增高。夏季旱涝灾害等级处在4以下且在1982年后干旱灾害开始加重。秋季1993年以后由干旱灾害转为洪涝灾害。冬季干旱灾害有逐年加强趋势。4)不同旱涝灾害等级的频率季节差异显著,旱涝灾害主要发生在夏季。空间上,干旱灾害主要分布在河南西部和北部、山东西部和南部、河北北部。洪涝灾害主要集中在河南北部和中部,山东西部和南部、河北西北部以及北京、天津市。本研究能为该区农业健康发展提供参考。

Ensemble empirical mode decomposition was applied to analyze the climate time series in this paper.Based on standardized precipitation evapotranspiration index of 266 grids from 1901 to 2015,then the drought and flood disasters rating sequence were identified,the periodicity of drought and flood disasters and the spatial distribution of frequency of them were analyzed.The following results were reached:(1)The mutation year of the series of drought and flood disasters characterized by SPEI-12 was 1940,the drought disasters mainly occurred before 1940,and the flood disasters concentrated after 1940,the fluctuation cycles were 4 years and 8 year on inter-annual scale,there were 13 years,29 years and 46 years on the decadal scale.(2)Extreme droughts and extreme floods occurred 556 times and 655 times,accounting for 1.76%and 2.08%of the total number,respectively,which indicating that extreme floods occurred more frequently than extreme drought disasters.However,the frequency of droughts(19.46%)was higher than that of floods(16.43%),the weather was partial drought.(3)The sequence of drought and flood disasters characterized by SPEI-3 has been decomposed by EEMD method,the res curve of spring showed that the level of floods had been gradually increasing since1994.The level of summer droughts and floods was below 4 and the summer droughts began to worsen after1982.In the autumn,the drought disasters turned into a flood disaster after 1993.Winter drought disaster had been strengthened year by year.(4)The frequencies of different levels of drought and flood showed significant differences in four seasons.The drought and flood disasters were mainly concentrated in the summer.Droughts disasters were mainly distributed in the western and northern parts of Henan Province,western and southern parts of Shandong Province,the northern part of Hebei province.Flood disasters were mainly concentrated in the northern and central parts of Henan Province,the west and south of Shandong Province,the northwest of Hebei Province,and Beijing and Tianjin city.