A Synergistic, Multi-Platform Approach to Deriving Optically Constrained Aerosol Column Products: Insights into Spatio-temporal dynamics of Black Carbon around Xuzhou and Dhaka

Abstract This study presents a top-down aerosol characterization by combining UV band information from TROPOMI and multi-waveband data from AERONET to constrain black carbon (BC) aerosol size and mixing state. The approach, applied to Xuzhou, China, and Dhaka, Bangladesh, reveals smaller BC cores and non-linear morphological influences in both cities. While Dhaka exhibits higher BC core concentrations (mean 5.3 mg m^(-2) vs 7.3 mg m^(-2) in), Xuzhou shows greater overall aerosol column mass and number concentration (mean 397.1 mg m^(-2) and 6.7 × 10^(11) # m^(-2) vs 231.1 mg m^(-2) and 3.8 × 10^(11) # m^(-2)), reflecting different emissions factors and scenarios, and their contribution to BC loading. Spatial analysis uncovers significant aerosol loading along Dhaka's urban riverbanks (BC column mass density 8-9 mg m^(-2)), and rapidly growing lower-tier cities in China, suggesting overlooked emission sources over these regions. The study reveals complex relationships between wind patterns, aerosol accumulation, and dispersion that challenge traditional seasonal dynamics, with significant aerosol accumulation observed in Xuzhou during moderate and high winds. These findings underscore how high-resolution data influences air quality assessments, and can be tailored using available remote sensing datasets to contribute valuable insights for effective air quality management and climate change mitigation.