Interdecadal variability of the intense typhoons in autumn

The interannual and interdecadal variability of the typhoon activity over the western North Pacific Ocean in autumn have received less attention. This study found that the activity of categories 4-5 typhoon (TY45) in autumn exhibits significant interdecadal variability. During active period, the warm SST anomalies and TY45 activity not only extend eastward but also expand westward. The eastward extension of warm SST over the equatorial central Pacific is associated with the eastward shift of the formation region of intense typhoons. Thus, the intense typhoons formed over the central Pacific have longer (shorter) journey and life span on the warm ocean during active (inactive) period. This relationship between the interdecadal variability of TY45 and SST over the equatorial central Pacific is similar to the relationship between interannual variability of tropical storms and ENSO. However, the westward extension of warm SST and TY45 activity during active period is dramatically different from the warm ENSO episodes. This study will further investigate the interdecadal variability of synoptic-scale eddy kinetic energy source in autumn.