The impact of ENSO on near-surface Beryllium-7

The concentration of near-surface Beryllium-7 contains valuable information about the atmosphere, e.g., the tropospheric circulation, precipitation pattern or specific atmospheric phenomena, like the El Nino Southern Oscillation. Here, we modelled the transport and deposition of Beryllium-7 from galactic cosmic rays for 1850-2100, using the ECHAM/MESSy atmospheric chemistry climate model, and analyzed the variability of near-surface Beryllium-7 due to the El Nino Southern Oscillation. We find that our simulated Beryllium-7 time series agree well with Beryllium-7 measurements from the international monitoring system of the Comprehensive Nuclear-Test-Ban Treaty Organization. The analysis of the time series reveals significant Beryllium-7 patterns for El Nino and La Nina in the equatorial Pacific region, controlled by precipitation anomalies and the respective state of the Walker Circulation. Furthermore, our simulations show an intensification of the Beryllium-7 pattern for El Nino and La Nina in the future. Additionally, our findings suggest that near-surface Beryllium-7 could be used as an additional indicator or even predictor of the upcoming phase of the El Nino Southern Oscillation.