Projection of climate change impact on tropical cyclone hazard in Western North Pacific basin

The uncertainty of climate change effect on the tropical cyclone (TC) frequency and intensity has big impact on TC hazard assessment. In this study, a statistical dynamics synthetic TC model is used to generate TCs in the Western North Pacific (WNP) basin. Accordingly, three approaches are proposed to study the climate change impact on TC induced extreme wind speeds, using marine and atmospheric parameters from global circulation models (GCMs). The study covers three timespans, historical (1981-2010), mid-century (2041-2070), and late-century (2071-2100) and focuses on the Shared Socioeconomic Pathway 585 (SSP585) scenarios. For the genesis model: Approach #1 uses the TC detection method to extract the TC genesis properties from GCMs; Approach #2 uses the statistical TC genesis index to evaluate the TC genesis information; and Approach #3 calculates the relative genesis change between timespans under GCMs and then uses it to scale the observed datasets. For the intensity model, Approaches #1 and #2 use the marine and atmospheric parameters from GCMs directly, while Approach #3 replaces the GCM future datasets by adding the relative change to the reanalysis datasets. A 50-year wind speed ratio between current and future scenarios is used to assess the impact on TC hazard. All approaches indicate that the climate impact on TC risk varies over the WNP basin, with coastal cities in high latitude more likely to experience increased extreme TC wind speeds than those at low latitude. Approaches #1 and #2 give close relative extreme wind speed change, compared to further larger increase by Approach #3.