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气候变化影响下的降水量周期变化对于认识鄱阳湖枯水具有重要意义。采用EEMD方法分别将实测和模拟年降水量分解成不同频率的成分,然后采用FFT求得各IMF分量周期,以便对比未来和基准期的周期变化。结果表明,鄱阳湖流域1961~2001年的实测年降水量序列整体存在2.5~3.5、6.5~8.0年的周期,较大尺度的周期表现不显著;ASD统计降尺度模型对序列的周期特性模拟能力良好。未来情况下,主周期相对基准期整体呈增大趋势,中小尺度周期仅有微小差别,较大尺度周期普遍增大,鄱阳湖流域年降水量过程波动剧烈程度降低。
The periodic variation of precipitation under the influence of climate change is of great significance for understanding the low water of Poyang Lake. The EEMD method is used to decompose the observed and simulated annual precipitation into different frequency components, and then the FFT is used to calculate the IMF component periods in order to compare the periodic changes with the future and reference periods. The results show that the observed annual precipitation series from 1961 to 2001 in Poyang Lake Basin are 2.5-5.5-6.5-8.0 years in total, and the periodicity of large scale is not significant. The ASD statistical downscaling model can simulate the periodic characteristics of the series good. In the future, the main period will increase with the increase of the base period, while the small and medium-scale periods will only be slightly different. The larger-scale periods will generally increase, and the annual precipitation in the Poyang Lake Basin will fluctuate drastically.