** Progress in Earth and Planetary Science is the official journal of the Japan Geoscience Union, published in collaboration with its 50 society members.

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    • Progress in Earth and Planetary Science
    • Progress in Earth and Planetary Science
    • Progress in Earth and Planetary Science
    • Progress in Earth and Planetary Science
    Progress in Earth and Planetary Science

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    Atmospheric and hydrospheric sciences

    202002202002

    Variations in Extreme Wave Events near a South Pacific Island under Global Warming: Case Study of Tropical Cyclone Tomas

    Kenji Taniguchi, Yoshimitsu Tajima

    Tropical cyclone, Climate change, Ocean waves, Numerical simulations, Ensemble simulation, Fiji

    The intensification of tropical cyclones (TCs) and wind-induced ocean waves is expected to be amplified under global warming conditions. In 2010, strong TC Tomas approached the Fiji Islands and caused severe damage. Here, an ensemble simulation technique is combined with a pseudo-global warming (PGW) method to investigate future variations in TCs and wind-induced ocean waves. Ensemble PGW simulations were implemented using the weather research and forecasting (WRF) model with five different future projections. Hindcast and PGW simulations showed similar tracks of Tomas. In four PGW simulations, the central pressures of the simulated TCs decreased. Enhanced near-surface wind was recognized in three PGW simulations around the Fiji main island (Viti Levu). In the other two future simulations, the surface wind speed was weaker than the one in the present climate because of the slight eastward shift in the track and delayed development of the TC. WaveWatchIII (WW3) was applied for offshore wave simulations forced by the wind field obtained by WRF simulation results. In three future simulations, a clear increase in the maximum significant wave height (Hs) was found on the southeastern coast of Viti Levu. One future simulation yielded almost the same offshore wave characteristics as those under the present climate. In another future simulation, the ensemble mean Hs was as high as that in the present climate, but extremely large Hs values were found in several ensemble members. Future simulations using multiple global climate model (GCM) projections showed possible variations in TCs and wind-induced ocean waves which is useful for the risk assessment of various hazards.