Finer Vertical Resolution Improves the Sudden Stratospheric Warming Prediction Through Better Representing Planetary Waves

Abstract Sudden stratospheric warmings (SSWs) strongly impact tropospheric weather, yet their accurate prediction remains a significant challenge. This study investigates the predictability of SSWs in the Whole Atmosphere Community Climate Model with different vertical resolutions. Results show that SSW onset can be successfully captured up to 5 days in advance with 70 vertical layers, notably shorter than ∼10‐day lead time achieved by operational models. In contrast, when vertical layers are increased to 138, the lead time can be extended to 10 days, with the improvement attributed to better prediction of planetary wave vertical propagation and the resultant wave‐mean flow interactions. Further analysis reveals that the SSW predictability is more sensitive to the vertical resolution between 0.1 and 100 hPa than in the troposphere or mesosphere and beyond. This study demonstrates that enhancing vertical resolution alone can substantially improve SSW prediction skill, despite using coarse horizontal resolution (∼1°) and simplified initialization.