Study on the influence of ENSO on total columns of ozone over the Tibetan Plateau

Abstract. The El Niño-Southern Oscillation (ENSO) and the distinctive topographic features of the Tibetan Plateau (TP) exert a significant influence on the stratosphere-to-troposphere transport (STT) process. Their combined effects further amplify the spatiotemporal variability of tropospheric ozone (O₃) concentrations. To investigate the impact of ENSO on total column ozone (TCO) over the TP and the underlying mechanisms, this study employs the Weather Research and Forecasting Model with Chemistry (WRF-Chem). Results demonstrate that the single-synthesis simulation using WRF-Chem outperforms the multi-year simulation of the Whole Atmosphere Community Climate Model (WACCM) in capturing tropospheric TCO, zonal wind, potential height, and temperature. Over the TP, except in autumn, the variations in TCO within the lower stratosphere and troposphere exhibit opposite phases during El Niño and La Niña years. Specifically, TCO in the lower stratosphere is primarily regulated by the Brewer-Dobson circulation (BDC) and potential height. In contrast, TCO in the troposphere is shaped not only by potential height but also by STT processes and regional vertical circulation. The thermal effect of the TP plays a pivotal role in modulating the subtropical jet stream (STJ), potential height, and vertical circulation—with notable phase reversals observed between El Niño and La Niña years. Furthermore, the thermal effect of the TP acts in synergy with the Hadley Circulation (HC) to drive changes in the STJ, thereby exerting a significant impact on the spatiotemporal distribution of tropospheric O₃ over the TP.