Factors affecting climate variability of basin‐wide western North Pacific tropical cyclone intensity

Abstract

Changes in the duration of tropical cyclones (TCs) and the embedded large‐scale environment along with TC tracks have a substantial impact on basin‐wide TC intensity. However, their relative importance in changes of basin‐wide TC intensity remains unclear. This study focuses on their contributions to change in TC intensity over the western North Pacific (WNP) basin using a TC intensity model. First, simulations using a TC intensity model with inputs of TC tracks and the embedded environment adequately capture the climate variability of the observed basin‐wide WNP TC intensity. It suggests that the climate variability of basin‐wide TC intensity largely depends on the synergistic changes in large‐scale environment and TC tracks. Sensitivity tests indicated that changes in TC tracks generally appear to be the most important factor affecting basin‐wide TC intensity on the interannual and interdecadal timescales. Changes in large‐scale environment play a limited role especially for weak‐to‐moderate TCs (i.e., tropical storms and Cat.1–3 TCs), while comparable impacts of change in TC tracks and large‐scale environment are found for intense TCs (i.e., Cat.4–5 TCs). Given that TC tracks remain unchanged, sensitivity simulations further show that TC duration plays a more crucial role in controlling basin‐wide TC intensity than the environmental fields. Moreover, weak‐to‐moderate TCs appear to be more sensitive to duration than intense TCs, in consistent with the dramatic changes in basin‐wide TC intensity for westward TCs that form in the South China Sea and the Philippine Sea with short TC duration. Results of this study would be helpful for climate prediction of basin‐wide TC intensity over the WNP basin.