2006 Volume 2 Pages 136-139
The reason for the record-breaking typhoon landfall on Japan in 2004 was examined by analyzing the behavior of tropical intraseasonal variation associated with the Madden-Julian Oscillation (MJO, Madden and Julian 1972).
There were three active phases of MJO in June, August and early October over the western North Pacific during the typhoon season in 2004. The monsoon trough was enhanced during the active phase of the MJO over the western North Pacific and generated most of the typhoons over the region. The steering flow anomaly persisted, due to the long duration of the active phase of the MJO over the western Pacific, and directed westward-northwestward from the TC genesis region with both anti-cyclonic (cyclonic) centers over east of Japan (east of the Philippines), and we suggest that the persisted steering flow anomaly provided a favorable condition for typhoon landfall on Japan in 2004.