Accelerated Increase in Tropical Cyclone Heat Potential in the Typhoon Rapidly Intensifying Zone during 1955-2020

抄録

Previous studies suggested that increases in ocean heat content result in strengthening of tropical cyclone (TC) and causing the associated disasters. In the western North Pacific (WNP), acceleration of increasing rates of tropical cyclone heat potential (TCHP: ocean heat content above 26°C from the surface) in the TC rapidly intensifying (RI: a 24-h intensity change of ≥ 30 kt) zone may have contributed to increases in TC intensity. However, there is no research on the relation of the acceleration of increasing rates to the variations in TCHP in a climatological view, differently from the relation to decadal variations such as Pacific Decadal Oscillation (PDO). This study focused on the relation of the variations in TCHP anomalies (TCHPA) to RITCs over the past six decades.

Although the annual mean TCHPA in the global ocean was not accelerated, the TCHPA accelerated recently in the late 1990s over the RI zone particularly in fall (October-December) in the WNP. The acceleration of the increase in TCHPA was possibly explained by the intensification of trade wind-driven ocean general circulation and the combination of the linear trend of TCHPA with PDO phase change.