Exploring Three-Dimensional Spatiotemporal Distribution of Aerosols in the Sichuan Basin

Abstract

This study investigates the three-dimensional spatiotemporal distribution of aerosols in the Sichuan Basin from 2006 to 2023 using data from the CALIPSO satellite. Taking advantage of CALIPSO’s high-resolution vertical and nighttime detection capabilities, the research provides a comprehensive analysis of aerosol optical depth (AOD), vertical structure, and aerosol type composition within the basin. The results reveal a distinct "high internal, low peripheral" AOD distribution pattern shaped by the basin’s topography. Overall AOD levels exhibited a declining trend, decreasing from approximately 0.4 in 2006 to around 0.3 in 2023. Seasonal variations show AOD peaks in summer and autumn, while winter is characterized by localized pollutant accumulation. Vertically, aerosols are primarily concentrated within the 0–3 km layer, with larger particles found below 5 km during the day and between 3–8 km at night. The proportions of aerosol species remained relatively stable across seasons and altitudes, indicating limited variability in aerosol types. Biomass fuel combustion and human activities are identified as the main sources of aerosols in the region. This study offers valuable insights into aerosol distribution dynamics in enclosed terrain regions and provides a scientific foundation for future research. Further work is recommended to quantitatively examine the driving forces behind aerosol distribution patterns, including meteorological, industrial, and climatic factors.