Anthropogenic activities have been increasingly strengthening the meridional temperature gradient in the upper atmosphere, which has a profound impact on the wind shear and turbulence in mid‐latitudes. Here we examined the trends of the wintertime jet stream and clear‐air turbulence at 250 hPa over the Eurasian. The zonal wind speed showed a significantly increasing trend in the region between 40°N and 60°N where the meridional temperature gradient between the equator and the pole were increasing sharply in the past 4 decades (1980–2019). In addition, there existed a clear trend toward stronger vertical shear at 250 hPa in the latitudinal zone between 30°N and 40°N where the zonal wind increased, while a declining trend was shown to the south of 30°N, according to three different reanalysis datasets, including ERA5, JRA55, and NCAR/NCEP, which may be related to the poleward shift of the subtropical jet stream. The turbulence, closely related to the occurrence of vertical wind shear, was found to become stronger in the latitudinal zone between 30°N and 40°N consequently. The projections based on Phase 6 of Coupled Model Intercomparison Project models show that the zonal wind speed in the mid‐latitudes will increase significantly for the period 2015–2100, especially between the latitudinal zone between 40°N and 60°N, and the corresponding vertical wind shear in this area tend to dramatically increase. The findings not only help us better understanding of turbulence occurrence in the past 40 years, but also have profound implications for the projection of turbulence occurrence under global warming over mid‐latitude regions of North Hemisphere.

中文翻译：

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冬季欧亚高层喷气流湍流增加：过去和未来

人为活动日益增强了高层大气的子午温度梯度，这对中纬度地区的风切变和湍流产生了深远的影响。在这里，我们研究了欧亚大陆上250 hPa冬季喷流和晴空湍流的趋势。在过去40年（1980-2019年），赤道和极点之间的子午温度梯度急剧增加，在40°N和60°N之间的区域，纬向风速显示出显着增加的趋势。另外，根据三位科学家的研究，在30°N和40°N之间的纬向区域纬向风增加的地方，在250 hPa处有一个明显的趋势，即垂直剪切力增强，而在30°N的南部显示出下降的趋势。不同的重新分析数据集，包括ERA5，JRA55和NCAR / NCEP，这可能与亚热带急流的极移有关。结果发现，与垂直风切变的发生密切相关的湍流在30°N至40°N的纬向区域变得更强。基于耦合模型比对项目模型第6阶段的预测表明，中纬度地区的纬向风速在2015–2100年期间将显着增加，尤其是在40°N至60°N的纬度带之间，以及相应的该区域的垂直风切变趋于急剧增加。这些发现不仅有助于我们更好地了解过去40年的湍流发生，而且对北半球中纬度地区全球变暖下湍流发生的预测具有深远的意义。