Evolving patterns of arctic aerosols and the influence of regional variations over two decades

This study aims to analyze the trends, causes, and future prospects of aerosols in the Arctic region using ground-based observations, satellite data, and reanalysis model data. An analysis of aerosol remote sensing data from AERONET stations in the Arctic from 2000 to 2023 showed a long-term decrease in aerosol optical depth (AOD), aligning with emission regulations in Europe and North America and changes in atmospheric circulation patterns. However, the maximum AOD values observed at AERONET stations in Canada and Russia during the period of 2018-2023 were up to five times higher than the long-term average. This significant increase highlights the potential influence of regional variations and external inputs in Arctic aerosol loading, and emphasizes the need for further investigation into the underlying mechanisms driving these anomalies. Satellite observations confirmed that these highs were associated with regional factors, such as the transport of smoke aerosols from wildfires originating at lower latitudes. Notably, the increase in Arctic aerosols coincided with a decrease in mid-latitude and tropical regions, suggesting the influence of long-range atmospheric transport. From 2000 to 2023, wildfire activity has trended downward in tropical and mid-latitude regions, but upward in the Arctic. However, record wildfire activity in 2019 and 2021 was strongly associated with increased aerosols in the Arctic. This is likely a result of increased temperatures and drier conditions due to climate change, which have intensified the frequency and intensity of wildfires. In fact, mean air temperatures in the summers of 2019 and 2021 were about 5 K above the average of the past 19 years, favorable conditions for wildfires. And changes in barometric pressure and wind direction influenced regional-scale aerosol dispersion characteristics in the Arctic. In conclusion, the recent sudden increase in aerosols in the Arctic was found to be due to wildfire activity and climate change.