Subsurface messenger for the annual maximum lifetime maximum intensity of tropical cyclones in the western North Pacific.

Given the large number of record-breaking tropical cyclones (TCs) in recent years, there is a pressing need to investigate how strong TCs respond to climate change. Here we find that the annual maximum lifetime maximum intensity (LMI) of TC in the western North Pacific is strongly correlated with the temperature of a subsurface water mass, exhibiting a multi-decadal V-shaped structure in the past four decades. This water mass originally forms and is subducted in the eastern North Pacific under the center of the North Pacific High (NPH). It is then transported along a subsurface path over approximately four years to the western boundary. Correspondingly, the annual maximum LMI can be predicted several years in advance based on the intensity of NPH. We propose a mechanism in which the highly variable heat content of the subsurface water mass modulates the under-storm sea surface temperature through TC-induced mixing and upwelling process.