Uncertainty in future projections of the North Pacific subtropical high and its implication for California winter precipitation change

Abstract This study examines future projections of sea level pressure change in the North Pacific and its impact on winter precipitation changes in California. The multimodel analysis, based on the Coupled Model Intercomparison Project phase 5 models under the Representative Concentration Pathway 8.5 scenario, shows a robust sea level pressure change in the late 21st century over the western North Pacific in which both the Aleutian Low and the North Pacific subtropical high (NPSH) shift poleward in concert with a widening of the Hadley cell. This change is partly explained by a systematic increase of static stability in the subtropics. Despite its robustness, the projected NPSH changes over the eastern North Pacific exhibit a substantial intermodel spread, contributing as a cause for uncertain projections of precipitation changes in California. This intermodel spread in the eastern North…