利用定义的年降水集中度和时段集中指数,研究了淮河流域1961—2015年降水年内分布非均匀性的年际变化特征。分析发现,淮河流域年内降水分布不均,且降水季节较为集中;年降水集中度呈增大趋势,自1990年后波动性明显增大。对季节和月份的降水集中指数的变化进行MK趋势检验分析,发现多数平均集中指数为正的月份(5—8月份)仍然呈增大趋势,多数平均集中指数为负的月份(4月份和10月份)仍然呈减小趋势,只有1个月(11月份)变化趋势相反。季节集中指数的变化和月份类似,平均为负的春季和秋季集中指数呈减小趋势,平均为正的夏季集中指数呈明显的增大趋势,冬季集中指数相对稳定。总体而言,淮河流域年内月和季节的降水集中指数变化趋势加剧了降水分布的两极化,表现出“干愈干,湿愈湿”的时相变化特征。
Abstract
The inter-annual variation of heterogeneous annual precipitation distribution over 1961-2015 was studied by using the precipitation concentration degree (PCD) and precipitation concentration index (PCI) previously defined by other researchers. Results revealed that precipitation concentrated in some seasons, indicating that the distribution of precipitation in Huaihe basin was quite uneven at annual scale. Annual PCD showed an increasing trend with apparent undulation since 1990. According to Mann-Kendall analysis on the data of monthly and seasonal PCI, most months in which the PCI values were averagely positive (from May to August) displayed an increasing trend, while most months in which the PCI values were averagely negative (in April and October) exhibited an decreasing trend, with only one month(November) changing in the opposite direction. The trend of seasonal PCI was similar to that of monthly PCI: in spring and autumn when PCI were averagely negative, PCI showed decreasing trends; in summer when PCI was averagely positive, an increasing trend; in winter, the change of PCI was insignificant. In general, the trends of seasonal and monthly PCI at annual scale exacerbated the polarization of precipitation distribution: wet periods are tending to be wetter and dry periods are getting dryer.
关键词
淮河流域 /
非均匀性 /
降水集中度 /
集中指数 /
两极化
Key words
Huaihe River Basin /
heterogeneity /
precipitation concentration degree /
concentration index /
polarization
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