Persistent heavy haze episodes have repeatedly shrouded North China in recent years. Besides anthropogenic emissions, natural dust also contributes to the aerosols in this region. Through continuous observation by a dual-wavelength Raman lidar, the primary aerosol types and their contributions to air pollution in North China were determined. The following three aerosol types can be classified: natural dust, anthropogenic aerosols, and the mixture of anthropogenic aerosols and dust (polluted dust). The classification results are basically consistent with the classification results from the cloud–aerosol lidar and infrared pathfinder satellite observations (CALIPSO) satellite measurements. The relative bias of the lidar ratio between the Raman lidar and CALIPSO is less than 25% over 90% of the cases, indicating that the CALIPSO lidar ratio selection algorithm is reasonable. The classification results show that approximately 45% of aerosols below 1.8 km are contributed by polluted dust during our one year observations. The contribution of dust increased with height, from 6% at 500 m to 28% at 1,800 m, while the contribution of anthropogenic aerosols decreased from 49% to 25%. In addition, polluted dust is the major aerosol subtype below 1.0 km in spring (over 60%) and autumn (over 70%). Anthropogenic aerosols contribute more than 75% of air pollution in summer. In winter, anthropogenic aerosols prevailed (over 80%) in the lower layer, while polluted dust (around 60%) dominated the upper layer. Our results identified the primarily aerosol types to assess the contributions of anthropogenic and natural sources to air pollution in North China, and highlight that natural dust plays a crucial role in lower-layer air pollution in spring and autumn, while controlling anthropogenic aerosols will significantly improve air quality in winter.

中文翻译：

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激光雷达量化华北地区粉尘和人为来源对气溶胶的贡献并经CALIPSO验证

持续的大雾霾事件近年来屡屡笼罩在华北地区。除了人为排放外，该地区的自然气溶胶也导致了气溶胶的产生。通过双波长拉曼激光雷达的连续观测，确定了华北地区主要的气溶胶类型及其对空气污染的贡献。可以将以下三种气溶胶类型进行分类：天然粉尘，人为气溶胶以及人为气溶胶和粉尘（污染粉尘）的混合物。分类结果与云气溶胶激光雷达和红外探路卫星观测（CALIPSO）卫星测量的分类结果基本一致。在90％的情况下，拉曼激光雷达和CALIPSO之间的激光雷达比率的相对偏差小于25％，表明CALIPSO激光雷达比选择算法是合理的。分类结果显示，在我们的一年观测中，低于1.8 km的气溶胶中约有45％是由污染的尘埃引起的。尘埃的贡献随着高度的增加而增加，从500 m处的6％上升到1,800 m处的28％，而人为气溶胶的贡献从49％下降到25％。此外，春季（超过60％）和秋季（超过70％）在1.0 km以下污染的粉尘是主要的气溶胶亚型。在夏季，人为气溶胶占空气污染的75％以上。在冬季，下层普遍存在人为气溶胶（超过80％），而上层则主要是受污染的粉尘（约60％）。我们的结果确定了主要的气溶胶类型，以评估人为和自然资源对华北地区空气污染的贡献，