ABSTRACT This paper presents an analysis of trends in six drought variables at 566 stations across India over the period 1901–2002. Six drought variables were computed using standardized precipitation index (SPI). The Mann-Kendall (MK) trend test and Sen’s slope estimator were used for trend analysis of drought variables. Discrete wavelet transform (DWT) was used to identify the dominant periodic components in trends, whereas the significance of periodic components was examined using continuous wavelet transform (CWT) based global wavelet spectrum (GWS). Our results show an increasing trend in droughts in eastern, northeastern and extreme southern regions, and a decreasing trend in the northern and southern regions of the country. The periodic component influencing the trend was 2–4 years in south, 4–8 years in west, east and northeast, 8–64 years in central parts and 32–128 years in the north; however, most of the periodic components were not statistically significant.

中文翻译：

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使用小波变换评估印度干旱趋势和变异性

摘要 本文分析了 1901-2002 年间印度 566 个站点的六个干旱变量的趋势。使用标准化降水指数 (SPI) 计算了六个干旱变量。Mann-Kendall (MK) 趋势检验和 Sen 斜率估计器用于干旱变量的趋势分析。离散小波变换 (DWT) 用于识别趋势中的主要周期性分量，而使用基于连续小波变换 (CWT) 的全局小波谱 (GWS) 检查周期性分量的重要性。我们的研究结果表明，东部、东北部和极南部地区的干旱呈增加趋势，而该国北部和南部地区则呈减少趋势。影响趋势的周期分量南部为2～4年，西部、东部和东北部为4～8年，中部8-64岁，北部32-128岁；然而，大多数周期性成分在统计上并不显着。