2004–2018 年间中国区域气溶胶时空变化特征研究

基于 2004–2018 年 MODIS 长期观测的气溶胶日产品 MOD04 L2, 利用线性倾向估计法和 AOD-AE 气溶胶类 型划分法, 得到中国区域长时间序列的气溶胶光学特性与气溶胶类型的时空变化规律。研究表明, 在此期间: (1) 550 nm 处气溶胶光学厚度 (AOD) 高值分布在海拔较低、人口密集、工业发达的大城市群, 低值分布在人烟稀少、植被覆 盖度高的山区和草原; Ångstrom ¨ 波长指数 (AE) 高值分布在四川盆地边缘、贵州等地区, 低值分布在西北沙漠地区。 (2) 中国 73% 的地区 AOD 呈减小趋势, “胡焕庸线”东部的 AE 整体也呈减小趋势, 且 AOD 与 AE 均在 2014–2018 年期 间明显减小。 (3) 在季节变化趋势方面, AE 与 AOD 基本相反, 城市工业型气溶胶与 AOD 相同, 而清洁大陆型气溶胶 与 AOD 相反。 (4) 清洁大陆型气溶胶占比在 2014 年之后逐年递增, 说明中国空气质量逐渐改善。

Spatio-Temporal Characteristics of Aerosols in China During 2004-2018

Based on MODIS long term observations of aerosol daily product MOD04-L2, the temporal and spatial variations of aerosol optical properties and aerosol types in China from 2004 to 2018 are obtained using linear tendency estimation and AOD-AE aerosol classification methods. It is shown that during 2004-2018 : (1) high aerosol optical depth (AOD), values (550nm) are distributed in large urban agglomerations with low altitude, dense population and developed industries, while low AOD values are distributed in sparsely populated areas with high vegetation coverage mountains and grasslands. Areas such as Guizhou and the edge of Sichuan Basin are highlighted with high Ångstrom exponents (AE) and northwestern desert area with low values. (2) In 73 percent regions of ¨ China, AOD shows a decreasing trend during the observation period, and AE in the Eastern part of the “Hu Huanyong Line” also shows a decreasing trend. Especially, it is found that both AOD and AE decreased significantly during 2014-2018. (3) In terms of seasonal and monthly change trends, AE and clean continental aerosol are opposite to AOD, while urban industrial aerosol is the same as AOD. (4) The proportion of clean continental aerosols has increased year by year since 2014, indicating that air quality in China has gradually improved.