The East Asian westerly jet (EAWJ) features large seasonal variations in its intensity and position and exerts profound influences on local precipitation. In this study, we found the amplified seasonality of the EAWJ in response to the mid‐Holocene forcing. Compared with the preindustrial, the summer EAWJ significantly weakens by 20 ± 4% and shifts northward by 4 ± 2° during the mid‐Holocene, while the winter EAWJ slightly strengthens by less than 5%. Two different mechanisms are proposed to explain the significant summer weakening. From the perspective of stationary waves, the deficient precipitation over the tropical northwest Pacific produces the anomalous cyclonic circulations in the upper troposphere. The easterly winds north of the cyclone act to decelerate the EAWJ. In terms of transient processes, the mid‐Holocene reduced midlatitude meridional temperature gradient suppresses the synoptic‐scale disturbances through changes in the atmospheric baroclinicity. The subsequent decrease in kinetic energy transformation from transient eddies to the mean flow contributes to the weakening of the EAWJ. The reduction of the meridional temperature gradient is related to the subtropical cooling, which is possibly caused by the excessive monsoon rainfall and enhanced convection over East and South Asia. Both mechanisms involve the influence of low‐latitude precipitation on the midlatitude jet stream behavior, which deserves more attention in future studies of the jet stream dynamics.

中文翻译：

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东亚西风急流对全新世中期强迫响应的季节性

东亚西风急流（EAWJ）的强度和位置具有较大的季节性变化，并对当地降水产生深远影响。在这项研究中，我们发现EAWJ对全新世中期强迫的季节性增加。与整个工业化前相比，夏季EAWJ在全新世中期明显减弱了20±4％，并向北偏移4±2°，而冬季EAWJ则略微增强了不到5％。提出了两种不同的机制来解释夏季明显减弱的现象。从静止波的角度来看，热带西北太平洋上的降水不足，在对流层上部产生了异常的气旋环流。旋风以北的东风使EAWJ减速。就瞬态过程而言，中全新世降低的中纬度子午温度梯度通过大气气压斜度的变化抑制了天气尺度的扰动。从瞬态涡流到平均流的动能转换的随后减少导致EAWJ的减弱。子午温度梯度的减少与亚热带冷却有关，这可能是由于季风降雨过多和东亚和南亚对流增强引起的。这两种机制都涉及低纬度降水对中纬度急流行为的影响，这在以后的急流动力学研究中应引起更多关注。从瞬态涡流到平均流的动能转换的随后减少导致EAWJ的减弱。子午温度梯度的减少与亚热带冷却有关，这可能是由于季风降雨过多和东亚和南亚对流增强引起的。这两种机制都涉及低纬度降水对中纬度急流行为的影响，这在以后的急流动力学研究中应引起更多关注。从瞬态涡流到平均流的动能转换的随后减少导致EAWJ的减弱。子午温度梯度的减少与亚热带冷却有关，这可能是由于季风降雨过多和东亚和南亚对流增强引起的。这两种机制都涉及低纬度降水对中纬度急流行为的影响，这在以后的急流动力学研究中应引起更多关注。