Abstract
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.
Highlights
The Arctic Oscillation (AO) is the primary reason for the interannual variability in the troposphere and lower stratosphere
The production rate of 7Be at any given latitude in the atmosphere does not change with the season, the seasonal intrusion of lower stratospheric air and washout of atmospheric aerosols carrying 7Be leads to the enrichment of 7Be during late winter and early spring, (a)
We showed that the ground levels of 7Be and 210Pb at the Nanning and Environmental Measurements Laboratory (EML) stations in Alaska (Barrow), Montgomery (Alabama), Australia (Perth, Tasmania, and Norfolk), New Zealand (Chatham), and American Samoa were positively and statistically significantly correlated with an increase in the positive AO index (AOI)
Summary
The Arctic Oscillation (AO) is the primary reason for the interannual variability in the troposphere and lower stratosphere. This paper adopts the Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model to calculate the origins of air masses reaching the Nanning sampling site, compares the Nanning results to Environmental Measurements Laboratory (EML) observations, and applies a regression model to study the correlations among the variables of AOI, precipitation, air mass origin (latitude, longitude, and altitude), 7Be, and 210Pb. Beryllium-7 and Lead-210 are Associated with an Increase in the Arctic Oscillation: Evidence from. We show that air movement in the polar stratosphere affects the tropical troposphere based on observations of radioactive materials near the ground in the tropics. These chemical observations further strengthen the dynamic aspects of stratosphere-troposphere coupling processes (Hoskins et al 1985). This work addresses the following issues. (1) A significant correlation has been observed between 7Be and AOI, proving that the impact of the AO from the NH polar stratosphere can be observed near the surface of the tropical troposphere. (2) The good linear correlations between 7Be and 210Pb indicate that the stratosphere and troposphere are coupled
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