Comparison of aerosol optical depth between the CALIPSO and the MODIS over the Sichuan Basin

CALIPSO, the first satellite capable of vertical atmospheric profiling, has revolutionized atmospheric research by providing unprecedented vertical resolution of aerosol distributions. In contrast, the Moderate Resolution Imaging Spectroradiometer (MODIS), a widely used passive remote sensing instrument, has demonstrated high reliability in aerosol detection. This study harmonizes the spatial resolution and temporal coverage of CALIPSO and MODIS Level 2 aerosol products over the Sichuan Basin, China, for the period 2007–2022. A detailed statistical comparison was conducted across annual, seasonal, monthly, and regional scales. Results indicate a consistent temporal trend in Aerosol Optical Depth (AOD) between the two datasets. Nonetheless, notable discrepancies persist, with larger differences observed in winter and spring, and smaller deviations in summer and autumn. Approximately 60% of the absolute AOD differences fall within the range of 0 to 0.2, indicating general agreement. MODIS exhibits greater sensitivity across the AOD span, particularly in regions of extreme values—tending to overestimate AOD in high-concentration areas, while CALIPSO reports higher values in low-concentration regions.