3:30 PM - 3:45 PM
[U02-07] Variations of atmospheric ozone distribution and climate since 850 CE estimated by MRI-ESM2.0
Keywords:Ozone, Climate change, Paleoclimate
Climate in the common era was affected by processes such as the variability of solar forcing, volcanic eruption, and anthropogenic CO2 emissions. These climate forcing would also affect the behavior of the atmospheric ozone. In the Paleoclimate Modelling Intercomparison Project Phase 4 (PMIP4), the climate change since 850 CE was simulated using multiple climate models. However, the dynamic response of atmospheric ozone during this period has been assessed only by one model (MRI-ESM2.0) in PMIP4 experiments. For this reason, the behavior and long-term evolution of the atmospheric ozone over the last millennium remains ambiguous. In this study, we analyze the results of the PMIP4 past1000 experiment conducted using the MRI-ESM2.0 (Yukimoto et al., 2019), which is the only PMIP4 model that couples with an interactive ozone chemistry model. By analyzing this experiment, we investigate the behaviors of atmospheric ozone to various climate forcings from 850 to 1849 CE. We conducted multiple linear regression analysis to isolate the impacts of the solar activity, volcanic eruptions, El Niño-Southern Oscillation (ENSO), and Quasi-Biennial Oscillation (QBO).
We show that the simulated total column ozone varied between 310 and 330 DU in this period. The 11-year cycle of the solar forcing results in the variations of the total column ozone of around 5 DU when the solar activity is high, reflecting the changes of the photodissociation rate of oxygen. We also show that the model simulates the stronger Brewer-Dobson circulation during the phases of El niño events, which affects the stratospheric ozone distribution. This result is consistent with the present-day observation and analyses based on reanalysis data (Diallo et al., 2019). We further show that the ozone concentrations in the lower stratosphere increase in the aftermath of large volcanic events, which would reflect the decrease of NOx owing to the heterogeneous reactions on sulfate aerosol surfaces (Tie and Brasseur, 1995; Aquila et al., 2013) or changes in atmospheric circulation owing to the warming in lower stratosphere caused by sulfate aerosols (Muthers et al., 2015). These results indicate that the atmospheric ozone distributions in the common era would be fluctuated by different processes including ENSO, solar activity, and/or volcanic events. To further elucidate the links of the atmospheric ozone variations and the surface temperature, compilation of high-resolution paleoclimate proxies and simulations using other Earth system models would be highly desirable.
We show that the simulated total column ozone varied between 310 and 330 DU in this period. The 11-year cycle of the solar forcing results in the variations of the total column ozone of around 5 DU when the solar activity is high, reflecting the changes of the photodissociation rate of oxygen. We also show that the model simulates the stronger Brewer-Dobson circulation during the phases of El niño events, which affects the stratospheric ozone distribution. This result is consistent with the present-day observation and analyses based on reanalysis data (Diallo et al., 2019). We further show that the ozone concentrations in the lower stratosphere increase in the aftermath of large volcanic events, which would reflect the decrease of NOx owing to the heterogeneous reactions on sulfate aerosol surfaces (Tie and Brasseur, 1995; Aquila et al., 2013) or changes in atmospheric circulation owing to the warming in lower stratosphere caused by sulfate aerosols (Muthers et al., 2015). These results indicate that the atmospheric ozone distributions in the common era would be fluctuated by different processes including ENSO, solar activity, and/or volcanic events. To further elucidate the links of the atmospheric ozone variations and the surface temperature, compilation of high-resolution paleoclimate proxies and simulations using other Earth system models would be highly desirable.