基于SPEI指数的阿克苏地区干旱时空分布特征

Spatiotemporal Distribution Characteristics of Drought in Aksu Region Based on SPEI Inde

摘要: 基于1961~2025年阿克苏地区5个气象站点(阿克苏、乌什、拜城、新和、沙雅)的逐日气象资料，计算了1、3、6、12个月四种时间尺度的标准化降水蒸散指数(SPEI)，并结合Mann-Kendall趋势检验、Sen斜率估计和干旱频率统计，分析了该地区干旱的年际变化、年代际演变、季节分布及空间格局。结果表明：(1) 近65年来，阿克苏站和乌什站呈显著干旱化趋势(MK-Z分别为−5.27和−2.41，均通过95%置信度检验)，沙雅站呈显著湿润化趋势(MK-Z = 2.32)，拜城站和新和站变化不显著，整体呈“西干东湿”格局。(2) 年代际上，1990年代为全区最湿润期，2000年代后干旱明显加剧。(3) 季节上，春季干旱最重(5站平均频率81.6%)，夏季次之(47.4%)，秋冬较少，春旱是该地区最突出的季节性特征。(4) SPEI-6和SPEI-12反映的中长期干旱频率普遍高于SPEI-1的短期干旱，说明该地区中长期水分亏缺问题较为突出。

Abstract: Based on daily meteorological data from five stations (Aksu, Wushi, Baicheng, Xinhe, and Shaya) in the Aksu region from 1961 to 2025, this study calculated the Standardized Precipitation Evapotranspiration Index (SPEI) at four time scales (1, 3, 6, and 12 months). By integrating the Mann-Kendall trend test, Sen’s slope estimator, and drought frequency statistics, the interannual variations, interdecadal evolution, seasonal distribution, and spatial patterns of drought in the region were analyzed. The results indicate that: (1) Over the past 65 years, the Aksu and Wushi stations exhibited significant aridification trends (MK-Z values of −5.27 and −2.41, respectively, both significant at the 95% confidence level), whereas the Shaya station presented a significant wetting trend (MK-Z = 2.32). Changes at the Baicheng and Xinhe stations were not statistically significant, resulting in an overall spatial pattern of “dry in the west and wet in the east”. (2) On an interdecadal scale, the 1990s marked the wettest period for the entire region, while drought intensified significantly after the 2000s. (3) Seasonally, spring droughts were the most severe, with an average frequency of 81.6% across the five stations, followed by summer (47.4%); droughts were less frequent in autumn and winter, highlighting spring drought as the most prominent seasonal characteristic of the area. (4) The frequency of medium- to long-term droughts, as reflected by SPEI-6 and SPEI-12, was generally higher than that of short-term droughts reflected by SPEI-1, indicating that water deficits in this region are predominantly a medium- to long-term issue.