Monitoring Surface Be-10/Be-7 Directly Reveals Stratospheric Air Intrusion in Sichuan Basin, China

Stratospheric air intrusion can break the balance of atmospheric properties such as chemicals and radiation affecting the atmosphere. The meteoric cosmogenic Be-7 and Be-10 are mainly produced between the lower stratosphere and the upper troposphere and then adsorbed on aerosols for transport, they are good tracers of the atmospheric mass transport. Here, Be-7 and Be-10 in aerosols were measured simultaneously by accelerator mass spectrometry, and after removing dust Be-10 interference, daily resolution Be-7 and Be-10 for the whole year in Chengdu (a major city in the Sichuan Basin of China) was obtained. The long-period tracing of stratospheric air intrusion in the Sichuan Basin area is realized by directly observing the surface Be-10/Be-7 ratio. This work confirms the influence of stratospheric air intrusion on the surface O-3 and atmospheric water vapor in the Sichuan Basin and finds that the stratospheric air intrusion degree in spring and summer is significantly higher than that in autumn and winter. The results indicate that high-resolution Be-10/Be-7 can provide effective and refined tracers for the atmospheric vertical motion. The new Be-7 and Be-10 observation records contribute to evaluating the impact on the environment and climate during the stratospheric air intrusion in the Sichuan Basin.