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1957-2018年永定河流域降雨时空演变规律研究

Research on the Temporal and Spatial Evolution of Precipitation in the Yongding River Basin from 1957 to 2018

  • 摘要: 基于永定河流域内14个气象站点1957-2018年逐日观测数据,采用线性倾向估计、距平分析、小波分析对永定河流域降雨时空演变规律进行了分析,采用旋转经验正交函数(Rotated Empirical Orthogonal Function,REOF)法对降雨进行特征分区并通过相关分析揭示流域降雨的主要相关因子。结果表明:在全球变暖的背景下,永定河流域降雨量呈下降趋势,下降速率为-2.88 mm/10 a,多年降雨量均值为389.22 mm。季尺度上,春秋两季降雨量呈上升趋势,以秋季降雨量上升最为明显,上升速率为3.75 mm/10 a;夏冬两季降雨量呈下降趋势,以夏季降雨量下降最为明显,下降速率为-8.14mm/10 a。小波分析结果表明,流域降雨量变化存在着28、15、4 a三个周期,以28 a为主周期。空间上,降雨量地域性差异较大,流域降雨量由东南平原区向西北山区递减。REOF分析表明,前六个模态可以较好地反映永定河流域降雨的空间分布类型;根据各模态高荷载区分布,永定河流域可划分为六个降雨区:Ⅰ区为西南大同盆地区,Ⅱ区为北部张家口地区、Ⅲ区为延怀盆地区、Ⅳ区为北京及冀西北盆地区、Ⅴ区为西北内蒙山区、Ⅵ区为滨海平原区;其中Ⅰ、Ⅴ区和Ⅳ、Ⅵ区分别受大陆性气候和季风气候的影响;Ⅱ、Ⅲ区受当地地形影响较为明显。相关分析结果表明,副热带南印度洋偶极子、蒸发、最高气温、日照时数和散射与降雨相关性显著。

     

    Abstract: Based on the daily data observed in 14 meteorology stations in the Yongding River Basin from 1957 to 2018, this paper analyzes the spatial-temporal characteristics of precipitation by using linear propensity estimation, anomalies analysis and wavelet analysis.The Rotated Empirical Orthogonal Function(REOF) method is used to divide characteristic zones and reveal the main correlative factors of precipitation in the basin through correlation analysis. Results show that under the background of global warming, the precipitation of the Yongding River Basin shows a decreasing trend with a rate of-2.88 mm/10 a with the average annual precipitation of 389.22 mm. From seasonal means, the precipitation in spring and autumn shows an increasing trend and the increase in precipitation is the most obvious in autumn with increasing rate of 3.75mm/10a.On the contrary, the precipitation in summer and winter shows a decreasing trend and the decrease in precipitation is the most obvious in summer with decreasing rate of-8.14 mm/10 a. Wavelet analysis shows that there are three cycles of 28, 15 and 4 a in the variation of precipitation, with 28 a as the main cycle. The main cycle time of precipitation in the Basin is 28 years. From spatial means, precipitation is significantly different, precipitation in the Basin decreases from the southeastern plain areas to the northwestern mountainous areas. The REOF analysis shows that first six modes can reflect the spatial distribution of precipitation in Yongding River Basin.According to the distribution of high load area in each mode,the Yongding River Basin can be divided into six zones: Zone Ⅰ is southwestern Datong Basin, Zone Ⅱ is northern Zhangjiakou, Zone Ⅲ is Yanhuai Basin, Zone Ⅳ is Beijing and northwestern Hebei Basin, Zone Ⅴis northwestern Inner Mongolia mountains and Zone Ⅵ is Coastal plains.Among these zones, Zone Ⅰ, Zone Ⅳ and Ⅵ are affected by continental climate and monsoon climate, respectively. Zone Ⅱ and Ⅲ are significantly affected by local topography. The correlation analysis results show that the Southern Indian Ocean Dipole(SIOD), evaporation, maximum temperature, sunshine time and scattering are significantly correlated with precipitation.

     

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