The Pacific Decadal Oscillation modulated marine heatwaves in the Northeast Pacific during past decades

Abstract The Pacific Decadal Oscillation has been suggested to play an important role in driving marine heatwaves the Northeast during recent decades. Here we combine observations and climate model simulations show that became longer, stronger more frequent off coast under a positive scenario, unlike what is found negative scenario. This primarily results from different mean-state sea surface temperatures between two phases. Compared cool (negative) phase of Oscillation, warmer coastal occur due reduced cold upwelling increased net downward heat flux. Model that, relative background anthropogenic global warming, period 2013–2022 prolongs duration by up 43% acts increase annual frequency 32% coast.