Climatology of low-level aerosol extinction coefficient of different aerosol types and their association with the meteorology during 2007–2021: Insights from the CALIPSO observation over China

The radiative and microphysical effects of aerosol in low-level layers (below 3 km) can have crucial and complicated impacts on modern weather and climate change. The Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) can provide a multiyear global aerosol distribution with high vertical resolution. The newest Level 3 aerosol profile data is used for the period 2007–2021 to analyze the seasonal-averaged vertically distributed aerosol extinction coefficient of different aerosol types over West and East China (WCN and ECN). This has been combined with the Modern Era Retrospective-Analysis for Research (MERRA-2) reanalysis data derived from meteorological variables to investigate their relationship for the study period. The results indicate that the aerosol types in the ECN are dominant with clean marine (CM), polluted continental/smoke (PC) and polluted dust (PD). Whereas, the desert dust (DD) is the main aerosol type found in WCN. In WCN, the vertical profile of DD is overlapped with total aerosol, and the extinction profile of PD is closer to total aerosol in ECN. This is attributed to the different aerosol anthropogenic sources and influence of meteorology. The vertical profile of aerosol presents smoother structure in ECN than in WCN due to more complex atmosphere dynamic. RH is the key meteorological factor that affects the aerosol extinction coefficient. In WCN, DD aerosol is mainly concentrated when the RH is ranged from 25 to 50%, whereas it is between 50 and 85% for PD in ECN. This is related to the pollution aerosol hygroscopicity growth for the observed bias.