State Key Laboratory of Information Engineering in Surveying, Mapping and Remote Sensing, Wuhan University, Wuhan 430079, China.
State Key Laboratory of Information Engineering in Surveying, Mapping and Remote Sensing, Wuhan University, Wuhan 430079, China.
Sci Total Environ. 2021 Apr 15;765:144241. doi: 10.1016/j.scitotenv.2020.144241. Epub 2020 Dec 24.
Himawari-8 aerosol products have been widely used to estimate the near-surface hourly PM concentrations due to the high temporal resolution. However, most studies focus on the evaluation model. As the foundation of the estimation, the relationship between near-surface PM and columnar aerosol optical depth (AOD) has not been comprehensively investigated. In this study, we investigate the relationship between PM and advanced Himawari imager (AHI) AOD for 2016-2018 across mainland China on different spatial and temporal scales and the factors affecting the association. We calculated the Pearson correlation coefficients and the PM/AOD ratio as the analysis indicators in 345 cities and 14 urban agglomerations based on the collocations of PM and AHI AOD. From 9:00 to 17:00 local time, the PM-AOD correlation become significantly stronger while The PM/AOD ratio markedly decrease in Beijing-Tianjin-Hebei, Yangtze River Delta, and Chengyu regions. The strongest correlation is between 12:00 and 14:00 LT (at noon) and between 13:00 and 17:00 LT (afternoon), respectively. The ratio in a day shows an obvious unimodal mode, and the peak occurred at around 10:00 or 11:00 LT, especially in autumn and winter. There is a pronounced variation of the PM-AOD relationship in a week during the winter. Moreover, there are the strongest correlation and the largest ratio for most urban agglomerations during the winter. We also find that PM and AOD are not always correlated under different meteorological conditions and precursor concentrations. Furthermore, for the scattering-dominated fine-mode aerosol, there is a high correlation and a low ratio between PM and AOD. The correlation between PM and AHI AOD significantly increases with increasing the number of AOD retrievals on a day. The findings will provide meaningful information and important implications for satellite retrieval of hourly PM concentration and its exposure estimation in China, especially in some urban agglomerations.
向日葵 8 气溶胶产品由于具有较高的时间分辨率，已被广泛用于估算近地表每小时 PM 浓度。然而，大多数研究都集中在评估模型上。作为估算的基础，近地表 PM 与柱状气溶胶光学深度 (AOD) 的关系尚未得到全面研究。在本研究中，我们在不同的时空尺度上，针对 2016 年至 2018 年中国大陆的 PM 与先进向日葵成像仪 (AHI) AOD 之间的关系以及影响这种关系的因素进行了研究。我们基于 PM 和 AHI AOD 的搭配，在 345 个城市和 14 个城市群中计算了 Pearson 相关系数和 PM/AOD 比作为分析指标。当地时间 9:00 至 17:00 之间，京津冀、长三角和成渝地区的 PM-AOD 相关性显著增强，PM/AOD 比值明显下降。最强的相关性分别出现在当地时间 12:00 至 14:00（中午）和 13:00 至 17:00（下午）。一天中的比值呈明显的单峰模式，峰值出现在当地时间 10:00 或 11:00 左右，尤其是在秋冬季节。冬季一周内 PM-AOD 关系的变化明显。此外，在冬季，大多数城市群的相关性最强，比值最大。我们还发现，在不同的气象条件和前体浓度下，PM 和 AOD 并不总是相关的。此外，对于以散射为主的细颗粒气溶胶，PM 和 AOD 之间具有较高的相关性和较低的比值。PM 和 AHI AOD 之间的相关性随着一天内 AOD 反演次数的增加而显著增加。这些发现将为中国，特别是一些城市群，提供有意义的信息和重要启示，有助于卫星每小时 PM 浓度的反演及其暴露评估。
