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Projection of Tropical Cyclone and Storm Surge

Introduction

Global tropical cyclone activity may play an important role in driving the ocean’s thermohaline circulation, which has an important influence on regional and global climate (Emanuel, 2001). Observational evidence showed an increase of intense hurricane activity in the North Atlantic since mid 1970’s, correlated with increases in tropical SSTs (IPCC, 2007). Theory and high resolution dynamical models both consistently indicate that global warming will cause the globally averaged intensity of tropical cyclones to increase, and modelling studies consistently project decreases in the globally averaged frequency of tropical cyclones (Knutson et al., 2010). Devastating natural disaster is likely to be caused by more intense typhoons, hurricanes and cyclones which give rise to heavier rain, more extreme winds, higher waves and storm surges. Extreme tropical cyclone related events have high potential of flooding along low-lying coastal areas, including the highly-populated and asset-rich Japanese bay areas and Asian megadeltas.

Previous studies (Sugi et al., 2002; Oouchi et al., 2006) concluded that the number of tropical cyclone will decrease in a future climate, based on results from an Atmospheric General Circulation Model (abbreviated as AGCM) projection by the JMA/MRI group (Mizuta et al., 2006). Yokoi and Takayabu (2009) examined typhoon cyclogenesis using CMIP3 (phase 3 of the Coupled Model Intercomparison Project) ensemble data and concluded that the cyclogenesis area will shift eastward. Although their results are useful climatological indicators, it is difficult to apply them to estimates of specific natural hazards, such as storm surges. Since stochastic analyses are necessary for disaster reduction planning, the number and intensity of projected typhoons by a single GCM does not provide enough information, therefore a stochastic typhoon model (denoted by STM hereafter) is necessary for engineering purposes.

The purpose of this study is to establish a STM for estimating characteristics of typhoons from cyclogenesis to cyclolysis in both present and future climate conditions in order to evaluate coastal hazard risks. Differences between statistical characteristics of the present and the future typhoons were estimated from projections by an AGCM under a climate change scenario and are taken into account in the stochastic modeling of future typhoons as a climate change signal.

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Collaborators

  • Hajime Mase, DPRI
  • Tomohiro Yasuda, DPRI
  • Sota Nakajo, DPRI
  • Yuta Hayashi, DPRI

Current results

Publications

  1. Yasuda, T. and H. Mase and N. Mori (2010) Projection of future typhoons landing on Japan based on a stochastic typhoon model utilizing AGCM projections, Hydrological Research Letters, Vol.4, pp.65–69. (10.3178/HRL.4.65)