Projected Response of Santa Ana Winds Over Southern California to Global Warming by a High-Resolution Climate Model

Santa Ana winds (SAWs), notorious for fueling the most destructive wildfires over Southern California, are exceptionally dry offshore katabatic winds that descend adiabatically from the inland arid plateau. Here, we investigate how model grid resolution affects the simulation of present and future SAWs using ensemble simulations from a newly developed climate model with varying atmospheric resolutions (100, 50, and 25 km). At finer resolutions, the model better resolves coastal mountains, strengthening the land-sea temperature gradients conducive to SAWs and enhancing adiabatic warming over the leeward side. Consequently, the frequency and intensity of SAWs at 25-km model resolution are significantly more realistic than at coarser resolution. As climate warms, while the occurrence of SAWs decreases across all resolutions (approximately −10%), the changes in their impacts are resolution dependent. At finer resolution, future SAWs are projected to further exacerbate wildfire risks over coastal Southern California due to an increased vapor pressure deficit.