Journal of Arid Meteorology ›› 2020, Vol. 38 ›› Issue (5): 709-715.DOI: 10.11755/j.issn.1006-7639(2020)-05-0709

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Causes of Anomalous Rainy Summer of 2018 in the Midwest of Inner Mongolia

LIU Wei, ZHAO Yanli   

  1. Inner Mongolia Climate Center, Hohhot 010051, China
  • Online:2020-10-30 Published:2020-10-30



  1. 内蒙古自治区气候中心,内蒙古 呼和浩特 010051
  • 通讯作者: 赵艳丽,女,高级工程师,主要从事气象灾害监测、预报预警和评估研究. E-mail:。
  • 作者简介:刘炜(1986— ),女,硕士,工程师,主要从事短期气候预测.
  • 基金资助:

Abstract: Based on the daily precipitation data at 107 weather stations in Inner Mongolia and NCEP/NCAR reanalysis data, the causes of anomalous heavy rain in the middle and west of Inner Mongolia in summer of 2018 were analyzed. The results show that the precipitation in Inner Mongolia in summer of 2018 was significantly more than the normal, it mainly concentrated in July, and the precipitation was 50% to 4 times more than the normal in the midwest. The anomalous configuration of circulation at different levels of troposphere was the main cause of more precipitation in summer of 2018 in midwest Inner Mongolia. There was a trough near Baikal Lake on 500 hPa, the blocking high near Ural Mountain and Okhotsk Sea was active, and the meridional span over mid-high latitudes increased, which was beneficial to moving southward of cold air. The ridge line of the western Pacific subtropical high was anomalous northward due to the strong East Asian summer monsoon, the water vapor supply was sufficient. The unstable atmospheric stratification provided sufficient energy for precipitation. The westerly jet axis was to the north, and the midwest Inner Mongolia located in the south side of the jet axis, which caused enhancement of divergence at upper level. Combined with the convergence at middle and lower level of troposphere, they led to the development of upward movement from the lower to the upper of troposphere. The westerly jet was to the north and its disturbance was weaker along north-south direction, and the convective activity over tropical northwestern Pacific was strong, which was conducive to motivate EAP wave, and resulted in maintaining steadily of the anomalously northward subtropical high over the mid-latitude region.

Key words: the midwest of Inner Mongolia, summer of 2018, anomalous rainy, East Asian westerly jet, EAP wave

摘要: 利用内蒙古107站逐日降水量、NCEP/NCAR逐日再分析资料,对2018年夏季内蒙古中西部地区异常多雨的成因进行分析。结果表明:2018年夏季内蒙古地区降水显著偏多,降水偏多时段主要集中在7月,中西部大部地区偏多5成至4倍。高低空环流的异常配置导致了内蒙古中西部地区2018年夏季降水异常偏多,即500 hPa高度场上贝加尔湖附近为低槽,乌拉尔山及鄂霍次克海附近阻塞高压活跃,有利于冷空气南下;东亚夏季风显著偏强,西太平洋副热带高压脊线较常年异常偏北,水汽供应充足;大气层结不稳定条件为降水提供了充足的能量;高空西风急流轴偏北使得内蒙古中西部地区高层辐散增强,配合中低层辐合运动,对流层整层均为上升运动;西风急流位置偏北及其南北向扰动偏弱以及热带西北太平洋对流活动强盛均有利于激发EAP波列,使得副高异常偏北稳定维持在中纬度地区。

关键词: 内蒙古中西部地区, 2018年夏季, 异常多雨, 东亚西风急流, EAP波列

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