Few studies have investigated the retreat of the East Asian summer monsoon (EASM) in comparison to its seasonal advances. This study examined the climatological characteristics of the EASM retreat based on the Japanese 55-year Reanalysis data and multiple observation data. First, the retreat date of EASM is defined based on the reversal of 850 hPa meridional winds over coastal East Asia. Then, the climatological characteristics of the EASM retreat are investigated based on the retreat date of the EASM. At lower troposphere, the differences of the 850-hPa winds between after and before the EASM retreat display an anticyclone (cyclone) over the East Asian continent (the subtropical western Pacific), resulting in the strengthening of northerly winds over the coastal region of East Asia. Such northerly winds lead to decrease of moisture transport over East Asia and bring colder air from higher latitudes to the coastal East Asia, both favoring the retreat of the EASM. At middle troposphere, the WPSH moves eastward, and a mid-latitude trough appears over northeast Asia. In addition, the difference fields show descending (ascending) motion and cold (warm) advection in the rear (front) of the mid-latitude trough. At upper troposphere, a divergent center exhibits a southeastward movement, which shifts from the Philippine Islands to the western North Pacific. As such, a convergence center appears over the coastal East Asia in the difference map. The retreat of the EASM is also associated with the decreased rainfall, the demise of the wet season, and the broadscale cooling over East Asia.

很少有研究调查东亚夏季风 (EASM) 的消退与其季节性推进的对比。本研究基于日本 55 年再分析资料和多次观测资料，研究了东亚夏季风撤退的气候学特征。首先，根据东亚沿海850 hPa经向风的反转来确定EASM的后退日期。然后，根据东亚夏季风退却日期，研究了东亚夏季风退却的气候特征。在对流层低层，东亚夏季风前后850 hPa风场差异显示东亚大陆（副热带西太平洋）出现反气旋（气旋），导致东亚沿海偏北风加强亚洲。这种偏北风导致东亚上空的水汽输送减少，并将冷空气从高纬度地区带到东亚沿海地区，有利于东亚夏季风后退。在对流层中部，副高东移，东北亚上空出现中纬度槽。此外，差异场显示中纬槽后（前）有下降（上升）运动和冷（暖）平流。在对流层上层，发散中心呈东南运动，从菲律宾群岛向北太平洋西部移动。因此，在差异图中，东亚沿海地区出现了一个会聚中心。东亚夏季风的消退还与降雨量减少、雨季结束以及东亚大范围降温有关。