Stratospheric Ozone Loss Enhances Summer Precipitation Over the Southern Slope of the Tibetan Plateau

Heavy summer precipitation over the southern slope of the Tibetan Plateau has dramatic influences on water resources and hydrological disasters in South Asia. It experienced increasing trends over 1979–1996 and decreasing trends over 1996–2022, which are not yet well understood. Here we show observational and numerical evidence that stratospheric ozone has significant impacts on long‐term trends of summer precipitation in this strong convection area. It is found that stratospheric ozone depletion, by modulating the lower stratospheric temperature and upper‐tropospheric static stability, enhances deep convection and precipitation over the southern slope of the Tibetan Plateau. The results suggest that the ozone recovery in the future may reduce the summer precipitation over the southern slope of the Tibetan Plateau in the first half of the 21st century, which would be imperative for future water resource management in South Asia. Plain Language Summary South Asia, with a population of more than 1.8 billion, is among the most vulnerable regions in the world in response to climate change and a global hotspot for water security. Heavy summer precipitation over the southern slope of the Tibetan Plateau, which directly affects North India and Nepal with a population of more than 200 million and has dramatic influences on water resources and hydrological disasters in South Asia, experienced increasing trends over 1979–1996 and decreasing trends over 1996–2022 (Figure 1). We find that the long‐term variations of the summer precipitation are likely related to the stratospheric ozone depletion and recovery over the Tibetan Plateau in recent decades. The convective precipitation over the southern slope of the Tibetan Plateau is modulated by the upper tropospheric static stability which is affected by the lower‐stratospheric temperature. We find that stratospheric ozone depletion, which radiatively cools the lower stratosphere, enhances the deep convection and precipitation. This work helps to understand the stratospheric contributions to the changes in the summer precipitation over the southern slope of the Tibetan Plateau and future water resource management in South Asia. Key Points Trends in heavy summer precipitation over the southern slope of the Tibetan Plateau are positive in 1979–1996 and negative in 1996–2022 Stratospheric ozone depletion led to lower stratospheric cooling and a reduction of upper‐tropospheric static stability Stratospheric ozone depletion e