Response of Landfalling Atmospheric Rivers on the U.S. West Coast to Local Sea Surface Temperature Perturbations

Abstract

AbstractAtmospheric rivers (ARs) play a crucial role in the hydroclimate of the U.S. west coast. While the impact of large‐scale sea surface temperature (SST) patterns on ARs is well recognized, the specific roles of local SST on ARs have not been systematically investigated. This study analyzed the landfalling ARs from two regional climate simulations that differ only in the local SST. With local SST warming, AR frequency increases across the U.S. west coast, with comparable contributions from the spatial expansion of ARs and emergence of new ARs. AR landfalling area, inland intrusion distance, and intensity also increase, with landfalling area showing the largest sensitivity. Although local SST warming only increases the AR moisture by ∼0.4%/K, AR‐related precipitation increases by 3%/K, demonstrating the important impact of local SST warming on intensifying storms. Hence, local SST is important for accurate depiction of ARs and their precipitation in the western United States.