Abstract:

The 2023 heat and drought event in Wuwei, Gansu, the worst in 60 years, caused significant economic losses. In order to enhance the forecast accuracy of extreme weather events and mitigate their impact, using precipitation, temperature and drought data from 1959 to 2023 from the national basic meteorological stations in Wuwei, along with the ENSO （El Niño and Southern Oscillation） event records from the National Climate Center, the influence of El Niño event on the arid climate of the region was analyzed by using climate statistics methods. The results showed that in the El Niño event occurring year, the region tends to experience higher temperatures of the whole year and reduced precipitation in summer and autumn, but increased precipitation in winter. Abnormal climate phenomenon may occur in all four seasons. Moreover, the probability of moderate to severe droughts increased significantly during these years. In the El Niño event ending year, the regional climate is characterized by higher temperature across all seasons, increased spring precipitation and decreased winter precipitation, alongside a heightened probability of extreme weather events. In the year following the end of El Niño event, approximately 25% of the time occurs a La Nina, while 50% of the time, another El Niño event may commence, with climate change primarily influenced by the current climatic event. The study also finds that the year immediately following the end of a La Niña event transitioning into an El Niño phase exhibits particularly pronounced climate anomalies and an increased likelihood of extreme weather.

Key words: El Niño event, precipitation, meteorological drought, similar year characteristics, Wuwei

摘要：

2023年甘肃武威发生了60 a一遇的高温干旱事件，造成巨大经济损失。为提高极端气候事件的预报预测精度并减轻其造成的损害，基于武威国家基本气象站1959—2023年逐日降水、气温和干旱实况资料，以及国家气候中心发布的ENSO（El Niño and Southern Oscillation，厄尔尼诺-南方涛动）事件记录，采用气候统计学方法分析厄尔尼诺事件对该地区干旱气候的影响。结果表明：在厄尔尼诺事件发生年，该区域倾向于出现全年气温偏高和夏秋季节降水偏少的现象，冬季降水则偏多，且春、夏、秋、冬季节均可能出现气候异常现象。此外，在这些年份中，中度到特重干旱的发生概率明显增加。在厄尔尼诺事件结束年，区域气候表现出四季气温偏高的特点，同时春季降水偏多，冬季降水偏少且极端天气事件发生概率上升。在厄尔尼诺事件结束的次年，约有25%的年份会发生拉尼娜事件，而50%的年份可能再次进入厄尔尼诺期，气候变化主要受当前气候事件的影响。研究还发现，在拉尼娜事件结束后立即进入厄尔尼诺期的年份，气候异常现象尤为显著，发生极端天气的概率增加。

关键词: 厄尔尼诺事件, 降水, 气象干旱, 相似年特征, 武威