Significant contribution of UTLS ozone variations on precipitation over Western Europe

Precipitation in Europe significantly influences local agriculture and water resources. Numerous research endeavours have explored the influence of tropospheric variables on precipitation variability in Europe. Recent investigations have identified a connection between alterations in high-latitude stratospheric ozone levels and precipitation patterns across Eurasia. This study investigates the correlation between the high-latitude stratosphere and precipitation trends in Western Europe, utilizing observational data, reanalysis, and atmospheric models, yielding new insights that upper tropospheric and lower stratospheric (UTLS) ozone in the northern high latitudes notably influence spring and autumn precipitation in Western Europe, and explained the mechanism. Increased UTLS ozone tends to enhance the precipitation in Western Europe, and vice versa. Further analysis reveals that elevated UTLS ozone radiatively warms the local region, shifting the polar jet stream over Europe equatorward in spring and autumn, which results in a cyclonic anomaly over Western Europe. This enhances the convection over Western Europe and transports more water vapor from the Atlantic Ocean. The influence of variations in UTLS ozone on precipitation patterns in Western Europe has been further corroborated through the sensitivity experiments with climate model. An increase of 20% in UTLS ozone across Europe, relative to the multi-year average, raises precipitation in Western Europe by 2.6–8 mm/month and decrease it by 10 mm/month to the north. Overall, our findings highlight the significant influence of the UTLS ozone on modulating spring and autumn precipitation in Western Europe, offering important implications into the prediction of future precipitation changes.