Interaction between atmospheric rivers and marine heatwaves in the North Pacific

Atmospheric rivers (ARs) and marine heatwaves (MHWs) are two major extreme events of the climate system that strongly influence the ocean–atmosphere interface, yet their mutual interactions remain poorly understood. Here we use long-term oceanic and atmospheric reanalysis datasets (OISST and ERA5) from 1982 to 2023 to quantify the interactions and feedbacks between ARs and MHWs over the North Pacific. Longer and more intense events exhibit a higher probability of overlapping, resulting in nearly 85% of ARs and 57% of MHWs being linked to the other system. Pronounced hotspots of co-occurrence emerge in the mid-latitudes, where both systems frequently develop. ARs promote ocean surface warming and exacerbate MHW intensity by enhancing surface heat fluxes dominated by latent heat, together with increased downward longwave and sensible heat fluxes over the North Pacific north of 40° N. Conversely, MHWs slightly suppress local AR intensity by weakening horizontal winds, while mesoscale convection and cyclonic disturbances disrupt integrated vapor transport. This effect is partially offset by enhanced moisture associated with stronger convection. These findings reveal a bidirectional coupling between oceanic and atmospheric extremes and highlight the need to examine their relationship across other ocean basins and under future warming scenarios to better anticipate compound climate risks.