Diversity of cross-pacific atmospheric river main routes

Abstract Atmospheric rivers distribute heterogeneously over the North Pacific. Here, we identify five cross-Pacific atmospheric river main routes (i.e., preferred migratory path) by Self-organizing map automatically. They originate from East Asia or the western North Pacific and terminate over western North America or Alaska. The cross-Pacific atmospheric river events are emphasized because they bring more long-lasting precipitation when landfalling over North America. In the synoptic scale, the presence and configurations of the intensive pressure dipole are the keys to cross-ocean ability and propagation direction of atmospheric rivers. In the interannual time scale, tropical oceanic forcing is found for the cross-Pacific atmospheric river from southeast China to the contiguous United States (i.e., in-phase Eastern Pacific El Niño-Southern Oscillation and the basin-wide mode of Indian Ocean) and the other two types of cross-Pacific atmospheric river events are more related to atmospheric internal variability (e.g., North Pacific Oscillation) with succeeding oceanic response.