Impacts of ENSO on Wintertime Total Column Ozone over the Tibetan Plateau Based on the Historical Simulations of Community Earth System Model

The ozone over the Tibetan Plateau (TP) plays an important role in protecting the local ecology by absorbing ultraviolet rays. The El Niño-Southern Oscillation (ENSO), recognized as the strongest interannual climate phenomenon globally, can affect the ozone variation over the TP. Based on the historical experimental simulation results of two Community Earth System Models (i.e. CESM2-WACCM and CESM2-WACCM-FV2) that include the coupling process of stratospheric chemistry-radiation-dynamics, this study analyzes the impact of ENSO on the wintertime total ozone column (TCO) over the TP from 1979 to 2014 and its physical processes. Compared with observations, the results show that the two models can basically simulate the spatial distribution of the climate state and standard deviation of the TP TCO and that CESM2-WACCM model performs better. During the winter when the ENSO signal is strongest, its warm phase, El Niño, cools the tropospheric temperature over the TP by modifying the atmospheric circulation, which induces a decrease in the tropopause height. Such a decrease in the tropopause height is responsible for the TP TCO increase. The cool phase La Niña is responsible for a decrease in the TCO over the TP, with a manner resembling the El Niño but with the opposite sign. Our results are consistent with previous observational analysis, and the relevant research provides valuable scientific insights for evaluating and improving Earth System Model that incorporates the coupling process of stratospheric chemistry-radiation-dynamics.