综合考虑单调与非单调特征的季节尺度降雨趋势研究

A study of seasonal scale rainfall trends integratingmonotonic and non-monotonic features

为了更为科学、综合、全面地分析降雨的趋势特征,基于广西龙滩流域58年降雨数据,首先采用线性趋势分析法分析龙滩流域季节尺度降雨的总体单调趋势变化速率,然后结合Spearman秩次检验法、Kendall秩次检验法以及Mann-Kendall趋势分析法分析降雨总体单调趋势的显著性程度,最后提出利用改进的ITA方法进一步挖掘降雨序列存在的非单调局部趋势特征。结果表明:龙滩流域春、秋两季降雨分别以速率-6.635 mm/10 a和-7.429 mm/10 a呈现总体单调减少的趋势特征,而夏、冬两季降雨则以速率1.511 mm/10 a和0.231 mm/10 a呈现增加的趋势;龙滩流域四季降雨总体变化趋势显著性程度不高,属于非显著性的上升或下降趋势;四季降雨局部非单调趋势特征较为明显,其中春秋两季降雨呈现出下降的局部趋势,其非单调趋势显著指标值在低值区分别为-0.03%和-19.43%,在高值区分别为-9.64%和-8.32%,夏季降雨则出现低值区下降而高值区上升的非单调局部趋势特点,冬季降雨呈现出上升的局部趋势特征,其中上升较为显著的是高值区降雨。

In order to analyze the trend characteristics of rainfall more scientifically and comprehensively,based on 58 years of rainfall data in the Longtan watershed of Guangxi,the paper firstly adopts the linear trend analysis method to analyze the overall monotonic trend change rate of seasonal-scale rainfall in the Longtan watershed and then combines the Spearman rank order test,Kendall rank order test and Mann Kendall trend analysis method to analyze the significant degree of the overall monotonic trend of rainfall.Finally,the improved ITA method was proposed to further explore the non-monotonic local trend characteristics of the rainfall series.The results show that the overall monotonic trend of rainfall in spring and autumn is decreasing at the rates of-6.635 mm/10 a and-7.429 mm/10 a respectively.While the increasing trend of rainfall in summer and winter is 1.511 mm/10 a and 0.231 mm/10 a.The local non-monotonic trend characteristics of rainfall in all seasons are more obvious,among which rainfall in spring and autumn shows a decreasing local trend,and its non-monotonic trend significant indicator values are-0.03%and-19.43%in the low-value area,and-9.64%and-8.32%in the high-value area,respectively.While rainfall in summer shows a non-monotonic local trend of decreasing in the low-value area and increasing in the high-value area characteristics,and winter rainfall shows a rising local trend characteristic,where the rise is more significant in the high-value area of rainfall.