Haze pollution in early winter (December and January) in the Yangtze River Delta (YRD) and in North China (NC) are both severe; however, their monthly variations are significantly different. In this study, the dominant large-scale atmospheric circulations and local meteorological conditions were investigated and compared over the YRD and NC in each month. Results showed that the YRD (NC) is dominated by the so-called Scandinavia (East Atlantic/West Russia) pattern in December, and these circulations weaken in January. The East Asian December and January monsoons over the YRD and NC have negative correlations with the number of haze days. The local descending motion facilitates less removal of haze pollution over the YRD, while the local ascending motion facilitates less removal of haze pollution over NC in January, despite a weaker relationship in December. Additionally, the monthly variations of atmospheric circulations showed that adverse meteorological conditions restrict the vertical (horizontal) dispersion of haze pollution in December (January) over the YRD, while the associated local weather conditions are similar in these two months over NC.

长江三角洲（YRD）和华北地区（NC）的初冬（12月和1月）的雾霾污染都非常严重；但是，它们的每月变化差异很大。在这项研究中，调查并比较了YRD和NC每月的主要大规模大气环流和当地气象条件。结果表明，YRD（NC）在12月以所谓的斯堪的纳维亚半岛（东大西洋/俄罗斯西部）为主，1月这些环流减弱。长三角和北半球的东亚12月和1月季风与霾天数呈负相关。在1月，局部下降运动有助于减少长三角地区烟霾污染，而局部上升运动有助于减少北半球地区烟霾污染，尽管12月的关系较弱。此外，大气环流的月度变化表明，不利的气象条件限制了长三角地区12月（1月）雾霾污染的垂直（水平）散布，而在这两个月中，北卡罗来纳州相关的当地天气条件相似。