白银市伏旱的气候变化特征及El Nino的影响

The Climatic Characteristics of the Mid-Summer Drought in Binyin and El Nino to Its Influence

摘要: 为农业抗旱减灾提供准确的气候信息，充分利用气候资源，调整作物种植结构和产业布局，加快白银市生态环境建设。利用白银市四站1957~2022年66年的降水量资料，计算了伏旱指数，使用EOF、线性倾向估计、非参数统计检验方法——MK、滑动谱分析等方法，分析了伏期干旱的气候变化特征。结果表明：(1) 白银市伏旱主要有两种变化形式：全市一致型和南北相反型；(2) 北部伏旱趋势不显著，南部伏旱有显著增加趋势，但北部的年代际变化要比南部大。北部2015年以来转入正常~多雨期，南部现在正处于干旱位相；(3) 北部伏旱无明显周期，南部有显著的3a周期；(4) 北部于1991年发生突变，干旱减弱，但2004年以后干旱又有所加剧；南部于1996年发生突变，干旱持续增强；(5) 当El Nino发生时，白银市夏季降水偏少几率增加，容易导致伏期出现干旱。该研究有助于进一步认识伏旱的气候变化特征和影响因素，为气候预测提供了重要信息。

Abstract: To provide accurate climate information for agricultural drought relief, make full use of climate re-sources, adjust crop planting structure and industrial layout, and accelerate the ecological environment construction in Baiyin City. Based on the precipitation data of four stations in Baiyin from 1957 to 2022, using EOF, linear tendency estimation, nonparametric statistical test methods—MK, sliding spectrum analysis and other methods, the mid-summer drought index was calculated and the climate change characteristics of summer drought were analyzed. The result shows that: (1) There are two main types of the mid-summer drought in Baiyin: The same type in the whole city and the opposite type in the north and the south. (2) The trend of the mid-summer drought in the north is not significant, but the trend of the summer drought in the south is significant, but the interdecadal variation in the north is larger than that in the south. The north has been back to normal-rainy period since 2015 and the south is now in a dry spell. (3) There is no obvious period of the mid-drought in the north, but there is a significant period of 3a in the south. (4) In 1991, there was a sudden change in the north, and the mid-drought weakened, but it intensified after 2004. In 1996, there was a sudden change in the south, and the mid-drought continued to intensify. (5) When El Nino occurs, there is less rainfall in Baiyin in the summer, which tends to lead to the mid-drought in the incubation period. This study is helpful to further understand the characteristics and influenc-ing factors of climate change, and provides important information for climate prediction.