内蒙古大部分地区属于温带大陆性季风气候区,气候脆弱、复杂多样。作为中国北方重要的生态安全屏障,在全球变暖的背景下,内蒙古夏季气温降水发生显著变化,该区域对气候变化的敏感性日渐凸显。基于气象站历史观测及全球再分析数据,分析近60 a内蒙古夏季气象要素变化特征及其对厄尔尼诺事件的响应,得出如下结论：（1） 近60 a内蒙古中部及以东大部分地区夏季降水量呈减少趋势,而气温则是全区性增温趋势。（2） 冬季厄尔尼诺指数与次年夏季气象要素的相关性呈年代际变化特征,且东部型厄尔尼诺次年夏季内蒙古大部地区降水偏多,气温偏低;中部型厄尔尼诺次年夏季内蒙古西北部降水偏多,而中东部大部降水偏少,全区气温偏高。（3） 分析不同型厄尔尼诺夏季降水差异的主要原因是2类厄尔尼诺事件中西太平洋副热带高压和异常反气旋环流以及中高纬度环流异常的强度和位置不同引起。东部型厄尔尼诺次年夏季,副高较常年偏南,欧亚中高纬地区双阻型环流异常,其间的低槽冷涡与上游阻高之间的偏北气流引起北冰洋水汽与副高西侧太平洋水汽在华北地区汇合并向东北输送,造成内蒙古降水异常偏多。对于中部型,副高位置较常年偏西偏北使偏南水汽转向东输送,同时中高纬度反气旋环流异常不利于高纬度水汽输送,使内蒙古大部地区水汽输送减小,降水较常年偏少。（4） 2类厄尔尼诺事件次年夏季印度洋海温异常引起的印度夏季风水汽输送对内蒙古夏季降水也有相当的作用。

A large part of Inner Mongolia has temperate mainland monsoon climate, which is fragile, complex, and diverse. As an important ecological security barrier in northern China, Inner Mongolia has experienced significant changes in summer temperature and precipitation under the background of global warming, and its sensitivity to climate change is becoming increasingly prominent. In this study, various characteristics of summer meteorological elements and their responses to El Niño events in Inner Mongolia in the past 60 years were analyzed on the basis of the historical observation of meteorological stations and global reanalysis data. The following conclusions were drawn. (1) In the past 60 years, precipitation in most parts of central and eastern Inner Mongolia decreased in summer, whereas temperature in the whole region increased. (2) The correlation between El Niño index in winter and meteorological factors in summer of the following year was characterized by interdecadal variation. In the following summer, eastern El Niño in most areas in Inner Mongolia had more precipitation and lower temperature. Central El Niño had more precipitation in the northwest of Inner Mongolia, less precipitation in most parts of the middle and east, and higher temperature in the whole region. (3) The main reasons of summer precipitation differences in various El Niño types included the different intensities and locations of the subtropical high in the Central and Western Pacific Ocean, abnormal anticyclone circulation, and circulation anomalies at middle and high latitudes in two types of El Niño events. In the following summer of eastern El Niño, the subtropical high was southward compared with that in the past, and double resistance circulation anomalies appeared at middle and high latitudes of Eurasia and Asia. The northerly airflow between the low trough cold vortex and the high upstream resistance caused the water vapor of the Arctic Ocean and the water vapor of the Pacific Ocean on the west side of the subtropical high to converge in North China and be transported to the northeast, resulting in more precipitation in Inner Mongolia. For the central type, the location of the subtropical high was west by north; consequently, water vapor moved from south to east. Anticyclone circulation anomalies at middle and high latitudes are not conducive to water vapor transport at high latitudes, thereby reducing precipitation and water vapor transport in most parts of Inner Mongolia. (4) Water vapor transport in summer monsoon was caused by the sea surface temperature anomaly in the following summer in the Indian Ocean and implicated in summer precipitation in Inner Mongolia.