Influence of stratospheric quasi-biennial oscillation on tropical cyclone tracks in the western North Pacific

The possible influence of the stratospheric quasibiennial oscillation (QBO) on tropical cyclone (TC) passages in the western North Pacific (WNP) is examined using TC data recorded by the Tokyo Typhoon Center and the QBO index derived from reanalysis data. The influence is observed to be significant. The number of TCs approaching the East China Sea is large during the westerly phase of the QBO; however, during the easterly phase, the number of TCs approaching the eastern offshore of Japan is large. This difference in the TC tracks is found to be related to the background flow change associated with .the QBO. However, the total number of TC events, over the WNP and the sum of the number of TCs approaching the aforementioned two regions appear to be unrelated to the QBO phases.