Abstract
Abstract. To better understand the aerosol properties over the Arctic, Antarctic and Tibetan Plateau (TP), the aerosol optical properties were investigated using 13 years of CALIPSO (Cloud–Aerosol Lidar and Infrared Pathfinder Satellite Observations) L3 data, and the back trajectories for air masses were also simulated using the Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model. The results show that the aerosol optical depth (AOD) has obvious spatial- and seasonal-variation characteristics, and the aerosol loading over Eurasia, Ross Sea and South Asia is relatively large. The annual-average AODs over the Arctic, Antarctic and TP are 0.046, 0.024 and 0.098, respectively. Seasonally, the AOD values are larger from late autumn to early spring in the Arctic, in winter and spring in the Antarctic, and in spring and summer over the TP. There are no significant temporal trends of AOD anomalies in the three study regions. Clean marine and dust-related aerosols are the dominant types over ocean and land, respectively, in both the Arctic and Antarctic, while dust-related aerosol types have greater occurrence frequency (OF) over the TP. The OF of dust-related and elevated smoke is large for a broad range of heights, indicating that they are likely transported aerosols, while other types of aerosols mainly occurred at heights below 2 km in the Antarctic and Arctic. The maximum OF of dust-related aerosols mainly occurs at 6 km altitude over the TP. The analysis of back trajectories of the air masses shows large differences among different regions and seasons. The Arctic region is more vulnerable to mid-latitude pollutants than the Antarctic region, especially in winter and spring, while the air masses in the TP are mainly from the Iranian Plateau, Tarim Basin and South Asia.
Highlights
As an important component, atmospheric aerosols play a crucial role in the Earth–atmosphere system (Garrett and Zhao, 2006; Ghan and Easter, 2006; Nabat et al, 2015; Wei et al, 2021; Xue et al, 2020)
Previous air mass back trajectory simulations in the polar regions found that it is difficult to simulate the seasonal difference in the air mass with short-term back trajectory simulation, while the long-term back trajectory simulation has great uncertainties in the spatial domain (Hirdman et al, 2010; Sharma et al, 2013); a 14 d back trajectory simulation was adopted in this study (Rousseau et al, 2006), and the simulation date was set as the 15th and last day of each month, which can help save a lot of computation sources while keeping the simulated back trajectories representative
In the Arctic, except for the island of Greenland, aerosol loadings are larger over the continent than over the ocean
Summary
Atmospheric aerosols play a crucial role in the Earth–atmosphere system (Garrett and Zhao, 2006; Ghan and Easter, 2006; Nabat et al, 2015; Wei et al, 2021; Xue et al, 2020). Many studies have been carried out on aerosol optical properties over the Arctic, Antarctic and TP, they are mainly based on the short-term ground remote-sensing or in situ observations, which has limited spatial representation (Chaubey et al, 2011; Cong et al, 2009; Eleftheriadis et al, 2004; Engvall et al, 2008; Pokharel et al, 2019) and inadequate information about the vertical distribution of aerosols. The aerosol optical properties over the Arctic, Antarctic and TP were investigated systematically, including the spatial and temporal distribution, vertical structure, and temporal trends of AOD and aerosol types. The back trajectory of air masses was performed to determine the influence of ambient aerosols on the study areas
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