Comparison of MODIS- and CALIPSO-Derived Temporal Aerosol Optical Depth over Yellow River Basin (China) from 2007 to 2015

In this study, Collection 6.1 (C6.1) of different aerosol optical depth (AOD) products of different spatial resolutions were used from the aqua moderate resolution imaging spectroradiometer (MODIS) including dark target (DT), deep blue (DB), deep blue (DB), and DT-DB (DTB). These products were compared with cloud-aerosol lidar, and infrared pathfinder satellite observation (CALIPSO) AOD retrievals over the Yellow River Basin (YERB), China from 2003 to 2017. The YERB was divided into three sub-regions, namely YERB₁ (the mountainous terrain in the upper reaches of the YERB), YERB₂ (the Loess Plateau region in the middle reaches of the YERB), and YERB₃ (the plain region downstream of the YERB). Errors and agreement between MODIS and CALIPSO data were reported using Pearson’s correlation (R) and relative mean bias (RMB). Results showed that the CALIPSO whole layers AOD (AOD_S) were better matched with MODIS AOD than the CALIPSO lowest layer AOD (AOD₁). The time series of AOD shows higher values in spring and summer, and a small difference in AOD products was observed in autumn. The overall average value of CALIPSO AOD and MODIS AOD both fitted the order: YERB₃ ' YERB₂ ' YERB₁. The CALIPSO AOD retrievals have the best consistency with the DTB10K and the lowest consistency with DT3K. Overall, the regional distributions of the CALIPSO AOD and MODIS AOD are significantly different over the YERB, and the difference is closely related to the season, region, and topography. This study can help researchers understand the difference of aerosol temporal and spatial distribution utilizing different satellite products over YERB, and also can provide data and technical support for the government in atmospheric environmental governance over YERB.