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首页> 外文期刊>Nordic hydrology >A multiscale time-space approach to analyze and categorize the precipitation fluctuation based on the wavelet transform and information theory concept
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A multiscale time-space approach to analyze and categorize the precipitation fluctuation based on the wavelet transform and information theory concept

机译：基于小波变换和信息论概念的降雨尺度多尺度时空分析方法

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摘要

The present study proposed a time-space framework using discrete wavelet transform-based multiscale entropy (DWE) approach to analyze and spatially categorize the precipitation variation in Iran. To this end, historical monthly precipitation time series during 1960–2010 from 31 rain gauges were used in this study. First, wavelet-based de-noising approach was applied to diminish the effect of noise in precipitation time series which may affect the entropy values. Next, Daubechies (db) mother wavelets (db5–db10) were used to decompose the precipitation time series. Subsequently, entropy concept was applied to the sub-series to measure the uncertainty and disorderliness at multiple scales. According to the pattern of entropy across scales, each cluster was assigned an entropy signature that provided an estimation of the entropy pattern of precipitation in each cluster. Spatial categorization of rain gauges was performed using DWE values as input data to k-means and self-organizing map (SOM) clustering techniques. According to evaluation criteria, it was proved that k-means with clustering number equal to 5 with Silhouette coefficient = 0.33 , Davis–Bouldin = 1.18 and Dunn index = 1.52 performed better in determining homogenous areas. Finally, investigating spatial structure of precipitation variation revealed that the DWE had a decreasing and increasing relationship with longitude and latitude, respectively, in Iran.
机译：本研究提出了一种时空框架，该框架使用基于离散小波变换的多尺度熵（DWE）方法对伊朗的降水变化进行分析和空间分类。为此，本研究使用了1960–2010年间31个雨量计的历史月降水时间序列。首先，应用基于小波的降噪方法来减少噪声在降水时间序列中的影响，这可能会影响熵值。接下来，使用Daubechies（db）母小波（db5-db10）分解降水时间序列。随后，将熵概念应用于子系列，以在多个尺度上测量不确定性和无序性。根据跨尺度的熵模式，为每个群集分配了一个熵签名，该签名提供了每个群集中降水熵模式的估计。使用DWE值作为k均值的输入数据和自组织图（SOM）聚类技术，对雨量计进行了空间分类。根据评估标准，证明聚类数等于5的k均值在Silhouette系数= 0.33，Davis–Bouldin = 1.18和Dunn指数= 1.52时，在确定同质区域方面表现更好。最后，对降水变化的空间结构进行调查后发现，伊朗的DWE分别与经度和纬度呈递减关系。

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