POLEWARD MIGRATION OF OBSERVED AND SIMULATED TROPICAL CYCLONE TRACKS IN THE WESTERN PACIFIC

Abstract

The Lifetime Maximum Intensity location for observed Tropical Cyclones (TCs) in the Western North Pacific (WNP) has been moving poleward since 1982 and can expose newly vulnerable populations. In this study we simulate TC tracks with the GFDL AM2.5-C360 model to deter- mine whether the trends in TC tracks in the WNP are attributable to SST-forced climate change or are simply the result of weather-scale variability. By analyzing model runs in conjunction with the observed record we find that the poleward trend in the location of lifetime maximum intensity (LMI) is not inevitable. In addition to this, the model allows us to look further back in time than the observational record is able to be trusted and we find that there is an equatorward trend in the location of LMI starting in the mid-century. We also find a significantly stronger westward trend in LMI location in the WNP moving the LMI location closer to land. This paper also drives home the impact of such shifts by showing the trends at landfall and how the location of landfall and number of TCs making landfall is changing with a similar trend.