Understanding drought characteristics is vital for sustainable societal and ecosystem functioning, especially in ongoing climate change. The study investigates the drought characteristics over the Nepal Himalaya using the standardized precipitation index (SPI) based on monthly precipitation data from 220 ground stations between 1980 and 2016 at seasonal and annual timescales. The results show that occurrences of drought are more frequent after the 2000s, intensifying their severity and duration. The cumulative probabilities of short‐term (SPI3) and long‐term (SPI12) drought during the period 1980–2016 were 17.1% and 23.5%, respectively. The short‐term drought over Nepal occurred with an average duration of 2.8 months and a severity of −4.3, whereas for long‐term drought the duration and severity were 8.6 months and −13.9, respectively. Meanwhile, the seasonal drought shows that the spring and autumn drought events were slightly higher than summer and winter drought. The wavelet power spectrum shows the variability signals of winter, spring and summer drought were 2–8 and 8–16 years; however, the autumn drought index only varied at 2–8 years. The NINO3.4 is the primary controlling mode of variability for summer and annual drought, whereas the dipole moment index (DMI) is used for the autumn drought at an interannual timescale. The decadal variability of summer and annual drought is linked with the Pacific Decadal Oscillation, whereas winter and spring drought are linked to the Arctic Oscillation. Furthermore, the study contributes to the understanding of the drought characteristics and its controlling factors of variability over Nepal.

中文翻译：

---

尼泊尔喜马拉雅山的干旱特征及其与气候指数的关系

了解干旱特征对于可持续的社会和生态系统功能至关重要，尤其是在持续的气候变化中。该研究使用标准化降水指数（SPI）来调查尼泊尔喜马拉雅山的干旱特征，该指数基于1980年至2016年之间220个地面站在季节和年度时间尺度上的月降水量数据。结果表明，干旱在2000年代以后更加频繁，加剧了干旱的严重性和持续时间。1980-2016年期间，短期（SPI3）和长期（SPI12）干旱的累积概率分别为17.1％和23.5％。尼泊尔境内发生的短期干旱平均持续时间为2.8个月，严重度为-4.3，而严重干旱的持续时间为-4.3，严重度为-13.9。同时，季节性干旱表明春季和秋季干旱事件略高于夏季和冬季干旱。小波功率谱显示冬季，春季和夏季干旱的变异性信号分别为2-8年和8-16年。但是，秋季干旱指数仅在2-8年间变化。NINO3.4是夏季和年度干旱变化的主要控制方式，而偶极矩指数（DMI）用于年际尺度上的秋季干旱。夏季和年度干旱的年代际变化与太平洋年代际涛动有关，而冬季和春季干旱与北极涛动有关。此外，该研究有助于了解尼泊尔的干旱特征及其变化​​的控制因素。