Abstract: The vertical structure of atmospheric aerosols affects aerosol optical characteristics, the distribution of atmospheric environmental pollution, and regional climate change. Based on the verification by using ground-based data, this paper studies the seasonal distribution and annual variation characteristics of the vertical structure of aerosols over sea and land in central Yangtze River Delta region from 2013 to 2022, using the aerosol extinction coefficient and its type information inverted from the cloud-aerosol lidar and infrared pathfinder satellite observer (CALIPSO) observations. The results show that the aerosol extinction coefficient over land is significantly higher than that over sea, and polluted continental and polluted dust aerosols dominate over land, while clean marine and dusty marine aerosols are predominant over sea. Specifically, in spring, under the influence of dust from the Mongolian Plateau and the Taklimakan Desert, as well as northerly winds, dust aerosols are transported over long distances to central Yangtze River Delta region, affecting both land and sea region. In summer, the rising smoke aerosols from urban and industrial development primarily concentrate at the altitude of 1.5–3.5 km over land, whereas marine aerosols dominate over sea, with their extinction coefficients at the altitude of 0 – 1.5 km significantly lower than those in other seasons. During autumn and winter, polluted dust and polluted continental aerosols over land accumulate mainly within the altitude of 0 – 1 km, with the ground-level aerosol extinction coefficient reaching its annual peak in winter (approximately 0.5 km-1), however, marine aerosols consistently account for a high proportion over sea, resulting in minimal seasonal variation of aerosol extinction coefficient. Overall, over the past decade, the aerosol optical depth (AOD) in the vertical column over both land and sea regions in central Yangtze River Delta region has shown a declining trend year by year.

Key words: Yangtze River delta, aerosols, extinction coefficient, cloud-aerosol lidar and infrared pathfinder satellite observations, vertical features, differences between sea and land