Impact of Tibetan Plateau Topographic Forcing on Arctic Stratospheric Circulation and Ozone

The Tibetan Plateau, the world’s highest plateau, is known as the ‘Third Pole’ on earth. Evaluating the impact of Tibetan Plateau topographic forcing on Arctic stratospheric circulation and ozone is a crucial step toward achieving a deeper comprehension of the role of topography uplift in driving paleoclimatic evolution and stratospheric dynamics and chemistry. Through topography experiments in the Whole Atmosphere Community Climate Model version 6, this study reveals that the Tibetan Plateau’s topographic influence on Arctic stratospheric circulation and ozone is strongest in winter, followed by spring and autumn, and weakest in summer. During winter, the Tibetan Plateau can generate more quasi-stationary planetary waves that propagate into the Arctic stratosphere, causing the Arctic stratospheric polar vortex to weaken and shift toward Eurasia. Specifically, the upper Arctic stratosphere experiences a 42.7% increase in the amplitude of planetary waves with wavenumber 1. Compared to the flattened topography, the Tibetan Plateau’s topography also increases significantly the ozone by 15% in the lower Arctic stratosphere, accompanied by the highest accumulation of total ozone appearing in the polar region north to the North American continent. The intensified residual mean circulation transport is principally responsible for the increase in ozone, and topography has a stronger impact on the vertical residual mean transport than on the meridional residual mean transport. Further examination demonstrates that the robust strengthening of planetary waves caused by topography significantly contributes to the enhancement of the residual mean circulation. In contrast, during summer, the planetary waves generated by the Tibetan Plateau’s topography struggle to propagate toward high latitudes, resulting in a minimal impact on Arctic stratospheric circulation and ozone.