Possible processes for cold Asia and America viewed from an atmosphere-ocean coupled system. (Upper left) Horizontal view of the process that warm Arctic upper air due to an underlying sea-ice hole allowed the jet stream to meander poleward. In response, the jet meandered southward, with cold intrusion into Asia and America. The presence of the warm sea-ice hole resulted in formation of cyclone-derived atmospheric rivers that penetrated into the Arctic with anomalous south winds toward the sea-ice hole. (Upper right) Vertical-meridional view from the Pacific to the Arctic. The injection of atmospheric rivers due to anomalous south winds made upper Arctic air warm, leading to poleward upward wind. The wind-driven ocean current injected warm seawater into the sea-ice hole, which further heated the overlying air. (Bottom) Symbols, (A–D), in the flow chart respectively correspond to individual processes. The process (A) indicates positive feedback among the atmospheric river, warm hole and cyclone. Red arrows (B) show local atmospheric processes that made upper air warm, illustrating in the upper right panel. Black arrows (C) show large-scale atmospheric processes, illustrating in the upper left panel. Blue arrows (D) show local oceanic processes illustrated in the upper right panel. Dotted thin arrows show feedback processes.