An empirical method is used to estimate the aerosol direct radiative forcing (ADRF) over 20^oN − 40^oN regions from March 2000 to March 2019. The ADRF is calculated as the difference between the cloud-free sky and clean-sky (non-aerosol) radiative fluxes, which are fitted to an exponential function of the aerosol optical depth (AOD). The regional averaged ADRFs are negative (cooling effect) at the surface (SUR) and the top of atmosphere (TOA) and positive (warming effect) in the atmosphere (ATM). The spatial and temporal distributions of ADRF are closely linked to the spatio-temporal distributions of AOD. Higher AOD and stronger ADRF are found in spring (March to May) and summer (June to August). ADRFs are larger in regions with frequent sandstorm outbreaks and rapid economic growth since 2000 than other regions. The uncertainty of ADRF due to data source is 1.12 W/m² at the surface and 0.91 W/m² at the TOA according to the stochastic error propagation function. The ADRFs in our study regions show statistically significant but different changes of −0.074 W/m² /year and 0.1 W/m² /year at the surface during 2000 to 2009 and 2010 to 2019, respectively. Recent trend analysis also shows that the reduced aerosol contributes to the increasing short-wave flux about 0.32 W/m² under the background of the global warming during the period from 2000 to 2019 in our study area, which indicates that it may alter the pattern of atmospheric circulation or enhance the global warming effect.

一种经验方法用于估计超过 20 ^o N − 40 ^o的气溶胶直接辐射强迫 (ADRF)从 2000 年 3 月到 2019 年 3 月的 N 个区域。 ADRF 计算为无云天空和清洁天空（非气溶胶）辐射通量之间的差异，它们与气溶胶光学深度 (AOD) 的指数函数拟合。区域平均 ADRF 在地表 (SUR) 和大气顶部 (TOA) 处为负值（冷却效应），在大气 (ATM) 中为正值（变暖效应）。ADRF的时空分布与AOD的时空分布密切相关。在春季（3 月至 5 月）和夏季（6 月至 8 月）发现更高的 AOD 和更强的 ADRF。2000 年以来沙尘暴暴发频繁、经济增长较快的地区，ADRFs 比其他地区大。由于数据源的 ADRF 不确定度为 1.12 W/m ²在地表和 0.91 W/m ²根据随机误差传播函数在 TOA 处。我们研究区域的 ADRF 在2000 年至 2009 年和 2010 年至 2019 年期间分别在地表显示出-0.074 W/m ² /年和0.1 W/m ² /年的统计显着但不同的变化。最近的趋势分析还表明，在我们研究区从 2000 年到 2019 年期间，在全球变暖的背景下，减少的气溶胶有助于增加约 0.32 W/m ²的短波通量，这表明它可能改变格局大气环流或增强全球变暖效应。