Interannual and Interdecadal Drivers of Meridional Migration of Western North Pacific Tropical Cyclone Lifetime Maximum Intensity Location

Abstract

Abstract Recent studies have noted a poleward shift in tropical cyclone (TC) lifetime maximum intensity (LMI) location. Whether this observed shift is due to global warming, natural variability, or a combination of both factors remains inconclusive. The western North Pacific (WNP) has been shown in prior research to be the most robust contributor to the observed poleward LMI migration. This study explores interannual and interdecadal climate drivers of WNP LMI location from 1979 to 2018. On interannual time scales, there are more northward-moving TC tracks during El Niño years compared with La Niña years. However, there is substantially smaller variance in the latitudinal distance from TC genesis latitude to LMI latitude than the variance in the TC genesis latitude. Thus, TC genesis El Niño years tend to reach their LMI at a lower latitude given the increased likelihood that they undergo genesis at a lower latitude. On decadal or longer time scales, global warming has contributed to the recent poleward shift of LMI location by causing more northwestward-/northward-moving TC tracks, while the PDO also significantly modulates decadal variability in TC genesis latitude, thus also contributing to LMI latitude changes. Further analysis of the extended period from 1960 to 2018 suggests that the trends in TC LMI latitude and TC tracks are dominated by global warming, and the PDO phase change likely reinforces this trend during 1979–2018. These three leading modes of climate variability (e.g., ENSO, PDO, and global warming) offer a more complete picture of the meridional migration of WNP LMI location on various time scales.