Dynamics of Successive Tropical Cyclone Tracks in the Northwest Pacific: TC-Induced Rossby Wave Modulation of the Subtropical High

Successive tropical cyclones (TCs) pose substantial challenges to coastal regions by amplifying hazards and complicating forecasts. However, the underlying mechanisms governing their interactions remain insufficiently explored. This study used statistical analyses to examine how a preceding tropical cyclone (TC1) might influence the track of a subsequent tropical cyclone (TC2) in the western North Pacific. Our results revealed distinct track patterns driven by interactions between TC1 and the subtropical high (STH) across four primary movement directions. When TC1 travels westward, it injects high-mass anomalies into the STH ridge that weaken its southern flank, while anticyclonic anomalies of the resulting Rossby wave train strengthen its northern flank, causing the STH to shift northward and steer TC2 northward. Conversely, when TC1 moves northeastward, its Rossby wave train interacts with the lower-latitude STH through constructive interference, amplifying the lower-latitude STH and causing it to extend westward, guiding TC2 westward or inducing a westward-turning trajectory. For northwestward- and northward-moving TCs, the steering mechanisms exhibit transitional characteristics, representing a gradual shift between the westward- and northeastward-propagating regimes. These findings offer new insights into the dynamic interplay between TCs and the STH, advancing our understanding of the mechanisms that govern the tracks of successive TCs.