Beryllium-7 and Lead-210 are Associated with an Increase in the Arctic Oscillation: Evidence from Atmospheric Aerosols in a Remote Tropical Region in East Asia

The Arctic Oscillation (AO) accounts for a large fraction of recent decadal climate trends in Northern Hemisphere (NH) high latitudes. In East Asia, an elevated AO index (AOI) was associated with warmer temperatures in middle- to high-latitude regions, colder temperatures over low-latitude regions, and elevated ozone intrusion from the stratosphere. Elevated beryllium-7 (⁷Be) is produced in the stratosphere. Few studies have discussed the relationship between ⁷Be and the AO. Here, we identify the AO signature in ⁷Be and lead (Pb)-210 observed at a tropical ambient monitoring site in Nanning (22.8°N, 108.5°E) during the December 2014–December 2017 period. Our results show that the ⁷Be and ²¹⁰Pb concentrations are positively and significantly correlated with the AOI (P < 0.01). These results show that elevated ⁷Be and ²¹⁰Pb are associated with an increase in the AOI, reflecting air masses originating from NH high latitudes and vertically from the high-latitude upper troposphere and lower stratosphere regions to tropical latitudes in East Asia. These results have been verified with ozonesonde data without seasonality and with two meteorological data sets. Our results are also confirmed by observational data over the Pacific regions. We conclude that the AO exerts impacts over the tropical regions in East Asia, and ⁷Be can be used as a tracer to track the impacts of the AO.