A comprehensive study on the regional and spatial distributions of aerosol columnar optical and physical characteristics utilizing high-quality Aerosol Robotic Network (AERONET) datasets over Asia (Central, South, South-East, and East Asia), along with spatiotemporal collocated validation of two highly-spatially resolved models (Modern-Era Retrospective Analysis for Research and Applications-2 (MERRA-2) and Copernicus Atmosphere Monitoring Service (CAMS)) simulated aerosol optical depth (AOD) and Ångström exponent (AE) on annual and seasonal scales, is conducted for the first time. AOD is the highest over South Asia in each season, followed by South-East, East, and Central Asia. Annual regional average AOD at 0.50 μm over South Asia is 0.61. Combined influence of both fine mode anthropogenic aerosol emissions from fossil fuel combustion and biomass burning, and coarse mode dust aerosols from seasonal transport lead to higher AOD and total volume concentration (TVC), and exhibit significant spatiotemporal variations. Coarse volume fraction (CVF) and effective radius (R) are higher over Central Asia due to the dominance of coarse dust aerosols. East and South-East Asia are dominated by fine mode aerosols and result in higher fine volume concentration (FVC), AE, fine mode fraction (FMF), and lower R. Compared to the other regions of the globe (except Africa), AOD is higher over Asia, with higher spatiotemporal variabilities in AOD, AE, FMF, and TVC. Over Asia, the agreement between AERONET and CAMS AOD is better than that of AERONET and MERRA-2 AOD. For high AOD conditions, underestimation in model AODs is higher, and lower fraction of model AODs satisfy the Global Climate Observing System (GCOS) requirement over all regions, and these are more pronounced over Asia. Biases in model AODs are higher over Asia compared to the other regions of the globe, and lower over North America, Europe, and Australia. Higher bias in model AEs compared to AODs over all the regions shows substantial challenges in simulating spectral AOD and appropriate contributions of fine and coarse mode aerosols. These findings over a global aerosol hotspot region, Asia, along with other regions of the globe are crucial for accurate simulation and fine-tuning of aerosol characteristics by regional and global models, and for reducing uncertainties in the assessment of radiative and climate impact of aerosols.

中文翻译：

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亚洲气溶胶的光学和物理特征：AERONET、MERRA-2 和 CAMS

利用亚洲（中亚、南亚、东南亚和东亚）的高质量气溶胶机器人网络 (AERONET) 数据集对气溶胶柱状光学和物理特性的区域和空间分布进行全面研究，并对两个区域进行时空并置验证高度空间分辨率模型（现代时代研究和应用回顾分析-2 (MERRA-2) 和哥白尼大气监测服务 (CAMS)）在年度和季节尺度上模拟气溶胶光学深度 (AOD) 和 Ångström 指数 (AE)，是首次进行。每个季节的 AOD 最高的是南亚，其次是东南亚、东亚和中亚。南亚 0.50 微米的年区域平均 AOD 为 0.61。化石燃料燃烧和生物质燃烧产生的细模式人为气溶胶排放以及季节性运输产生的粗模式粉尘气溶胶的综合影响导致较高的 AOD 和总体积浓度 (TVC)，并表现出显着的时空变化。由于粗粉尘气溶胶占主导地位，中亚地区的粗体积分数 (CVF) 和有效半​​径 (R) 较高。东亚和东南亚以精细模式气溶胶为主，导致较高的精细模式气溶胶 (FVC)、AE、精细模式分数 (FMF) 和较低的 R。与全球其他地区（非洲除外）相比，AOD高于亚洲，AOD、AE、FMF 和 TVC 的时空变异性更高。在亚洲，AERONET和CAMS AOD之间的协议比AERONET和MERRA-2 AOD之间的协议要好。对于高 AOD 条件，模型 AOD 的低估程度更高，并且模型 AOD 满足所有地区全球气候观测系统 (GCOS) 要求的比例较低，这在亚洲更为明显。与全球其他地区相比，亚洲模型 AOD 的偏差较高，而北美、欧洲和澳大利亚的偏差较低。与所有区域的 AOD 相比，模型 AE 的偏差较高，这表明在模拟光谱 AOD 以及细模式和粗模式气溶胶的适当贡献方面存在巨大挑战。这些关于全球气溶胶热点地区、亚洲以及全球其他地区的发现对于通过区域和全球模型准确模拟和微调气溶胶特性以及减少气溶胶辐射和气候影响评估的不确定性至关重要。