Ongoing Poleward Migration of Tropical Cyclone Occurrence Over the Western North Pacific Ocean

The long-term change of tropical cyclone (TC) occurrence (TCO) was investigated by combining TC track density function and empirical orthogonal function methods to consider TC duration through a new perspective. Pronounced ongoing poleward migration of TCO was found for 1982-2018. This change has primarily resulted from the modification of TC propagation from westward to northward since 1998. A cyclonic anomaly of the large-scale environmental steering flow centered on East Asia was found based on a comparison of 1982-1997 and 1998-2018 periods. The cyclonic anomaly encompasses the southerly anomaly south of 20 degrees N, which is the mainspring of the poleward migration of TCO, while the extra warming along the coast of China also favors this long-term change. This study made it possible to analyze discrete spatiotemporal TC observations continuously and provided helpful techniques for projecting TC changes using numerical methods. Plant Language Summary Tropical cyclones can greatly damage areas near landfall because of the strong winds and torrential rain while benefiting areas further from the cyclone center with plentiful freshwater. In this respect, the regional impact of tropical cyclones is associated with the activity of tropical cyclones, and studies on tropical cyclone occurrence and its changes are essential to assess the potential impact of cyclones on human society. This study focused on the change of tropical cyclone occurrence from 1982 to 2018 and found a remarkable northward shift since 1998, whereas cyclones previously traveled in a largely westward direction. The ongoing northward shift of tropical cyclone occurrence is primarily the result of a southerly anomaly south of 20 degrees N. This change increases the threat of tropical cyclones in East Asian countries.